当前期刊: Plant, Cell & Environment Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Intervening in sibling competition for assimilates by controlled pollination prevents seed abortion under postpollination drought in maize
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-24
    Si Shen; Xiao‐Gui Liang; Li Zhang; Xue Zhao; Yun‐Peng Liu; Shan Lin; Zhen Gao; Pu Wang; Zhi‐Min Wang; Shun‐Li Zhou
    更新日期:2020-01-24
  • Woody tissue photosynthesis reduces stem CO2 efflux by half and remains unaffected by drought stress in young Populus tremula trees
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-23
    Linus De Roo; Roberto Luis Salomón; Kathy Steppe

    A substantial portion of locally respired CO2 in stems can be assimilated by chloroplast‐containing tissues. Woody tissue photosynthesis (Pwt) therefore plays a major role in the stem carbon balance. To study the impact of Pwt on stem carbon cycling along a gradient of water availability, stem CO2 efflux (EA), xylem CO2 concentration ([CO2]), and xylem water potential (Ψxylem) were measured in 4‐year‐old Populus tremula L. trees exposed to drought stress and different regimes of light exclusion of woody tissues. Under well‐watered conditions, local Pwt decreased EA up to 30%. Axial CO2 diffusion (Dax) induced by distant Pwt caused an additional decrease in EA of up to 25% and limited xylem [CO2] build‐up. Under drought stress, absolute decreases in EA driven by Pwt remained stable, denoting that Pwt was not affected by drought. At the end of the dry period, when transpiration was low, local Pwt and Dax offset 20% and 10% of stem respiration on a daily basis, respectively. These results highlight (a) the importance of Pwt for an adequate interpretation of EA measurements and (b) homeostatic Pwt along a drought stress gradient, which might play a crucial role to fuel stem metabolism when leaf carbon uptake and phloem transport are limited.

    更新日期:2020-01-24
  • Photosystem II 22kDa protein level ‐ a prerequisite for excess light‐inducible memory, cross‐tolerance to UV‐C and regulation of electrical signalling
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-23
    Magdalena Górecka; Maria Lewandowska; Joanna Dąbrowska‐Bronk; Maciej Białasek; Anna Barczak‐Brzyżek; Milena Kulasek; Jakub Mielecki; Anna Kozłowska‐Makulska; Piotr Gawroński; Stanisław Karpiński

    It is well known that PsbS is a key protein for the proper management of excessive energy in plants. Plants without PsbS cannot trigger non‐photochemical quenching, which is crucial for optimal photosynthesis under variable conditions. Our studies showed wild‐type plants had enhanced tolerance to UV‐C‐induced cell death (CD) upon induction of light memory by a blue or red light. However, npq4‐1 plants, which lack PsbS, as well as plants overexpressing this protein (oePsbS), responded differently. Untreated oePsbS appeared more tolerant to UV‐C exposure, whereas npq4‐1 was unable to adequately induce cross‐tolerance to UV‐C. Similarly, light memory induced by episodic blue or red light was differently deregulated in npq‐4 and oePsbS, as indicated by transcriptomic analyses, measurements of the trans‐thylakoid pH gradient, chlorophyll a fluorescence parameters, and measurements of foliar surface electrical potential. The mechanism of the foliar CD development seemed to be unaffected in the analysed plants and is associated with chloroplast breakdown. Our results suggest a novel, substantial role for PsbS as a regulator of chloroplast retrograde signalling for light memory, light acclimation, CD, and cross‐tolerance to UV radiation.

    更新日期:2020-01-24
  • Estimating photosynthetic traits from reflectance spectra: A synthesis of spectral indices, numerical inversion, and partial least square regression
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-10
    Peng Fu; Katherine Meacham‐Hensold; Kaiyu Guan; Jin Wu; Carl Bernacchi

    The lack of efficient means to accurately infer photosynthetic traits constrains understanding global land carbon fluxes and improving photosynthetic pathways to increase crop yield. Here we investigated whether a hyperspectral imaging camera mounted on a mobile platform could provide the capability to help resolve these challenges, focusing on three main approaches, i.e., reflectance spectra‐, spectral indices‐, and numerical model inversions‐based partial least square regression (PLSR) to estimate photosynthetic traits from canopy hyperspectral reflectance for eleven tobacco cultivars. Results showed that PLSR with inputs of reflectance spectra or spectral indices yielded a R2 of ~0.8 for predicting Vcmax and Jmax, higher than a R2 of ~0.6 provided by PLSR of numerical inversions. Compared to PLSR of reflectance spectra, PLSR with spectral indices exhibited a better performance for predicting Vcmax (R2 = 0.84 ± 0.02, RMSE = 33.8 ± 2.2 𝜇𝑚𝑜𝑙 𝑚−2 𝑠−1) while a similar performance for Jmax (R2 = 0.80 ± 0.03, RMSE = 22.6 ± 1.6 𝜇𝑚𝑜𝑙 𝑚−2 𝑠−1). Further analysis on spectral resampling revealed that Vcmax and Jmax could be predicted with ~10 spectral bands at spectral resolution less than 14.7 nm. These results have important implications for improving photosynthetic pathways and mapping of photosynthesis across scales.

    更新日期:2020-01-24
  • Mid‐infrared spectroscopy is a fast screening method for selecting Arabidopsis genotypes with altered leaf cuticular wax
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-21
    Na Liu; Lifang Zhao; Lily Tang; Jarvis Stobbs; Isobel Parkin; Ljerka Kunst; Chithra Karunakaran

    Arabidopsis eceriferum (cer) mutants with unique alterations in their rosette leaf cuticular wax accumulation and composition established by gas chromatography have been investigated using attenuated total reflection (ATR)‐Fourier transform infrared (FTIR) spectroscopy in combination with univariate and multivariate analysis. Objectives of this study were to evaluate the utility of ATR‐FTIR for detection of chemical diversity in leaf cuticles, obtain spectral profiles of cer mutants in comparison with the wild type, and identify changes in leaf cuticles caused by drought stress. FTIR spectra revealed both genotype‐ and treatment‐dependent differences in the chemical make‐up of Arabidopsis leaf cuticles. Drought stress caused specific changes in the integrated area of the CH3 peak, asymmetrical and symmetrical CH2 peaks, ester carbonyl peak and the peak area ratio of ester CO to CH2 asymmetrical vibration. CH3 peak positively correlated with the total wax accumulation. Thus, ATR‐FTIR spectroscopy is a valuable tool that can advance our understanding of the role of cuticle chemistry in plant response to drought and allow selection of superior drought‐tolerant varieties from large genetic resources.

    更新日期:2020-01-22
  • Genotypic variation in source and sink traits affects the response of photosynthesis and growth to elevated atmospheric CO2
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-21
    Denis Fabre; Michael Dingkuhn; Xinyou Yin; Anne Clément‐Vidal; Sandrine Roques; Armelle Soutiras; Delphine Luquet

    This study aimed to understand the response of photosynthesis and growth to e‐CO2 conditions (800 vs. 400 μmol mol−1) of rice genotypes differing in source–sink relationships. A proxy trait called local C source–sink ratio was defined as the ratio of flag leaf area to the number of spikelets on the corresponding panicle, and five genotypes differing in this ratio were grown in a controlled greenhouse. Differential CO2 resources were applied either during the 2 weeks following heading (EXP1) or during the whole growth cycle (EXP2). Under e‐CO2, low source–sink ratio cultivars (LSS) had greater gains in photosynthesis, and they accumulated less nonstructural carbohydrate in the flag leaf than high source–sink ratio cultivars (HSS). In EXP2, grain yield and biomass gain was also greater in LSS probably caused by their strong sink. Photosynthetic capacity response to e‐CO2 was negatively correlated across genotypes with local C source–sink ratio, a trait highly conserved across environments. HSS were sink‐limited under e‐CO2, probably associated with low triose phosphate utilization (TPU) capacity. We suggest that the local C source–sink ratio is a potential target for selecting more CO2‐responsive cultivars, pending validation for a broader genotypic spectrum and for field conditions.

    更新日期:2020-01-22
  • Pst DC3000 infection alleviates subsequent freezing and heat injury to host plants via a salicylic acid‐dependent pathway in Arabidopsis
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-21
    Za Khai Tuang; Zhenjiang Wu; Ye Jin; Yizhong Wang; Phyo Phyo Zin Oo; Guoxin Zuo; Huazhong Shi; Wannian Yang

    Abiotic stresses greatly affect the immunity of plants. However, it is unknown whether pathogen infection affects abiotic stress tolerance of host plants. Here, the effect of defense response on cold and heat tolerance of host plants was investigated in Pst DC3000‐infected Arabidopsis plants, and it was found that the pathogen‐induced defense response could alleviate the injury caused by subsequent cold and heat stress (38°C). Transcriptomic sequencing plus RT‐qPCR analyses showed that some abiotic stress genes are up‐regulated in transcription by pathogen infection, including cold signaling components ICE1, CBF1, and CBF3, and some heat signaling components HSFs and HSPs. Moreover, the pathogen‐induced alleviation of cold and heat injury was lost in NahG transgenic line (SA‐deficient), sid2‐2 and npr1‐1 mutant plants, and pathogen‐induced expression of cold and heat tolerance‐related genes such as CBFs and HSPs, respectively, was lost or compromised in these plants, indicating that salicylic acid signaling pathway is required for the alleviation of cold and heat injury by pathogen infection. In short, our current work showed that in fighting against pathogens, host plants also enhance their cold and heat tolerance via a salicylic acid‐dependent pathway.

    更新日期:2020-01-22
  • Mechanical stimulation in Brachypodium distachyon: implications for fitness, productivity and cell wall properties
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-18
    Agnieszka Gladala‐Kostarz; John H Doonan; Maurice Bosch

    Mechanical stimulation, including exposure to wind, is a common environmental variable for plants. However, knowledge about the morphogenetic response of the grasses (Poaceae) to mechanical stimulation and impact on relevant agronomic traits is very limited.

    更新日期:2020-01-21
  • Neither xylem collapse, cavitation or changing leaf conductance drive stomatal closure in wheat
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-17
    Déborah Corso; Sylvain Delzon; Laurent J. Lamarque; Hervé Cochard; José M. Torres‐Ruiz; Andrew King; Tim Brodribb

    Identifying the drivers of stomatal closure and leaf damage during stress in grasses is a critical prerequisite for understanding crop resilience. Here we investigated whether changes in stomatal conductance (gs) during dehydration were associated with changes in leaf hydraulic conductance (Kleaf), xylem cavitation, xylem collapse and leaf cell turgor in wheat (Triticum aestivum). During soil dehydration the decline of gs was concomitant with declining Kleaf under mild water stress. This early decline of leaf hydraulic conductance was not driven by cavitation, as the first cavitation events in leaf and stem were detected well after Kleaf had declined. Xylem vessel deformation could only account for <5% of the observed decline in leaf hydraulic conductance during dehydration. Thus we concluded that changes in the hydraulic conductance of tissues outside the xylem were responsible for the majority of Kleaf decline during leaf dehydration in wheat. However, the contribution of leaf resistance to whole plant resistance was less than other tissues (<35% of whole plant resistance) and this proportion remained constant as plants dehydrated, indicating that Kleaf decline during water stress was not a major driver of stomatal closure.

    更新日期:2020-01-21
  • Silencing of OsCV (CHLOROPLAST VESICULATION) Maintained Photorespiration and N‐assimilation in Rice Plants Grown under Elevated CO2
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-17
    Kamolchanok Umnajkitikorn; Nir Sade; Maria del Mar Rubio Wilhelmi; Matthew E. Gilbert; Eduardo Blumwald

    High CO2 concentrations stimulate net photosynthesis by increasing CO2 substrate availability for Rubisco, simultaneously suppressing photorespiration. Previously, we reported that silencing the CHLOROPLAST VESICULATION (CV) gene in rice increased source fitness, through the maintenance of chloroplast stability and the expression of photorespiration‐associated genes. Since high atmospheric CO2 conditions diminished photorespiration, we tested whether CV‐silencing might be a viable strategy to improve the effects of high CO2 on grain yield and N‐assimilation in rice. Under elevated CO2, OsCV expression was induced and OsCV was targeted to peroxisomes were it facilitated the removal of OsPEX11‐1 from the peroxisome and delivered it to the vacuole for degradation. This process correlated well with the reduction in the number of peroxisomes, the decreased catalase activity and the increased H2O2 content in WT plants under elevated CO2. At elevated CO2, CV‐silenced rice plants maintained peroxisome proliferation, photorespiration and displayed higher N assimilation than WT plants. This was supported by higher activity of enzymes involved in NO3− and NH4+ assimilation and higher total and seed protein contents. Co‐immunoprecipitation of OsCV‐interacting proteins suggested that, similar to its role in chloroplast protein turnover, OsCV acted as a scaffold, binding peroxisomal proteins.

    更新日期:2020-01-21
  • Cytosolic glyceraldehyde‐3‐phosphate dehydrogenase 2/5/6 increase drought tolerance via stomatal movement and reactive oxygen species scavenging in wheat
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-13
    Lin Zhang; Daili Lei; Xia Deng; Fangfang Li; Haikun Ji; Shushen Yang

    Drought is a major threat to wheat growth and crop productivity. However, there has been only limited success in developing drought‐hardy cultivars. This lack of progress is due, at least in part, to a lack of understanding of the molecular mechanisms of drought tolerance in wheat. Here, we evaluated the potential role of three cytosolic glyceraldehyde‐3‐phosphate dehydrogenases (TaGAPC2/5/6) under drought stress in wheat and Arabidopsis. We found that TaGAPC2/5/6 all positively responded to drought stress via reactive oxygen species (ROS) scavenging and stomatal movement. The results of yeast co‐transformation and electrophoretic mobility shift assay showed that TaWRKY33 acted as a direct regulator of TaGAPC2/5/6 genes. The dual luciferase reporter assay indicated that TaWRKY33 positively activated the expression of TaGAPC2/5/6. The results of bimolecular fluorescence complementation and yeast two‐hybrid system demonstrated that TaGAPC2/5/6 interacted with phospholipase Dδ (PLDδ). We then demonstrated that TaGAPC2/5/6 positively promoted the activity of TaPLDδ in vitro and in vivo. Furthermore, lower PLDδ activity in RNAi wheat could lead to less PA accumulation, causing higher stomatal aperture sizes under drought stress. In summary, our results establish a new positive regulatory mechanism of TaGAPCs which helps wheat fine‐tune their drought responses.

    更新日期:2020-01-14
  • Plasticity of Phymatotrichopsis omnivora infection strategies is dependent on host and nonhost plant responses
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-13
    Prasanna Kankanala; Piet Jones; Raja Sekhar Nandety; Daniel A. Jacobson; Kirankumar S. Mysore

    Necrotrophic fungi constitute the largest group of plant fungal pathogens that cause heavy crop losses world‐wide. Phymatotrichopsis omnivora is a broad host, soil borne necrotrophic fungal pathogen that infects over 2,000 dicotyledonous plants. The molecular basis of such broad host range is unknown. We conducted cell biology and transcriptomic studies in Medicago truncatula (susceptible), Brachypodium distachyon (resistant/nonhost) and Arabidopsis thaliana (partially resistant) to understand P. omnivora virulence mechanisms. We performed defense gene analysis, gene enrichments and correlational network studies during key infection stages. We identified that P. omnivora infects the susceptible plant as a traditional necrotroph. However, it infects the partially‐resistant plant as a hemi‐biotroph triggering SA mediated defense pathways in the plant. Further, the infection strategy in partially resistant plants is determined by the host responses during early infection stages. Mutant analyses in A. thaliana established the role of small peptides PEP1 and PEP2 in defense against P. omnivora. The resistant/nonhost B. distachyon triggered stress responses involving sugars and aromatic acids. Bdwat1 mutant analysis identified the role of cell walls in defense. This is the first report that describes the plasticity in infection strategies of P. omnivora providing insights into broad host range.

    更新日期:2020-01-13
  • Shade‐avoidance responses become more aggressive in warm environments
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-10
    Sofía Romero‐Montepaone; Sofía Poodts; Patrick Fischbach; Romina Sellaro; Matias D. Zurbriggen; Jorge J. Casal

    When exposed to neighbour cues, competitive plants increase stem growth to reduce the degree of current or future shade. The aim of this work is to investigate the impact of weather conditions on the magnitude of shade‐avoidance responses in Arabidopsis thaliana. We first generated a growth rate database under controlled conditions and elaborated a model that predicts daytime hypocotyl growth as a function of the activity of the main photo‐sensory receptors (phytochromes A and B, cryptochromes 1 and 2) in combination with light and temperature inputs. We then incorporated the action of thermal amplitude to account for its effect on selected genotypes, which correlates with the dynamics of the growth‐promoting transcription factor PHYTOCHROME‐INTERACTING FACTOR 4. The model predicted growth rate in the field with reasonable accuracy. Thus, we used the model in combination with a worldwide dataset of current and future whether conditions. The analysis predicted enhanced shade‐avoidance responses as a result of higher temperatures due to the geographical location or global warming. Irradiance and thermal amplitude had no effects. These trends were also observed for our local growth rate measurements. We conclude that, if water and nutrients do not become limiting, warm environments enhance the shade avoidance response.

    更新日期:2020-01-13
  • Molecular and physiological responses during thermal acclimation of leaf photosynthesis and respiration in rice
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-10
    Fatimah Azzahra Ahmad Rashid; Peter A. Crisp; You Zhang; Oliver Berkowitz; Barry J. Pogson; David A. Day; Josette Masle; Roderick C. Dewar; James Whelan; Owen K. Atkin; Andrew P. Scafaro

    To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas‐exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with Rdark (leaf dark respiratory CO2 release) and An (net CO2 assimilation) changes. With longer exposure, the central respiratory protein cytochrome c oxidase (COX) declined in abundance at 40/35°C. In contrast to Rdark, An was maintained across the three growth temperatures in ND leaves. Soluble sugars did not differ significantly with growth temperature, and growth was fastest with extended exposure at 40/35°C. The results highlight that acclimation of photosynthesis and respiration is asynchronous in rice, with heat‐acclimated plants exhibiting a striking ability to maintain net carbon gain and growth when exposed to heat‐wave temperatures, even while reducing investment in energy‐conserving respiratory pathways.

    更新日期:2020-01-11
  • Water use strategy affects avoidance of ozone stress by stomatal closure in Mediterranean trees—A modelling analysis
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-10
    Yasutomo Hoshika; Silvano Fares; Elisa Pellegrini; Adriano Conte; Elena Paoletti

    Both ozone (O3) and drought can limit carbon fixation by forest trees. To cope with drought stress, plants have isohydric or anisohydric water use strategies. Ozone enters plant tissues through stomata. Therefore, stomatal closure can be interpreted as avoidance to O3 stress. Here, we applied an optimization model of stomata involving water, CO2, and O3 flux to test whether isohydric and anisohydric strategies may affect avoidance of O3 stress by stomatal closure in four Mediterranean tree species during drought. The data suggest that stomatal closure represents a response to avoid damage to the photosynthetic mechanisms under elevated O3 depending on plant water use strategy. Under high‐O3 and well‐watered conditions, isohydric species limited O3 fluxes by stomatal closure, whereas anisohydric species activated a tolerance response and did not actively close stomata. Under both O3 and drought stress, however, anisohydric species enhanced the capacity of avoidance by closing stomata to cope with the severe oxidative stress. In the late growing season, regardless of the water use strategy, the efficiency of O3 stress avoidance decreased with leaf ageing. As a result, carbon assimilation rate was decreased by O3 while stomata did not close enough to limit transpirational water losses.

    更新日期:2020-01-11
  • Foliar herbivory by caterpillars and aphids differentially affects phytohormonal signalling in roots and plant defence to a root herbivore
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-10
    Peter N. Karssemeijer; Michael Reichelt; Jonathan Gershenzon; Joop van Loon; Marcel Dicke

    Plant‐mediated interactions are an important force in insect ecology. Through such interactions, herbivores feeding on leaves can affect root feeders. However, the mechanisms regulating the effects of above‐ground herbivory on below‐ground herbivores are poorly understood. Here, we investigated the performance of cabbage root fly larvae (Delia radicum) on cabbage plants (Brassica oleracea) previously exposed to above ground herbivores belonging to two feeding guilds: leaf chewing diamondback moth caterpillars (Plutella xylostella) or phloem‐feeding cabbage aphids (Brevicoryne brassicae). Our study focusses on root‐herbivore performance and defence signalling in primary roots by quantifying phytohormones and gene expression. We show that leaf herbivory by caterpillars, but not by aphids, strongly attenuates root herbivore performance. Above‐ground herbivory causes changes in primary roots in terms of gene transcripts and metabolites involved in plant defence. Feeding by below‐ground herbivores strongly induces the jasmonate pathway in primary roots. Caterpillars feeding on leaves cause a slight induction of the primary root jasmonate pathway and interact with plant defence signalling in response to root herbivores. In conclusion, feeding by a leaf chewer and a phloem feeder differentially affects root‐herbivore performance, root‐herbivore‐induced phytohormonal signalling, and secondary metabolites.

    更新日期:2020-01-11
  • Over‐accumulation of abscisic acid in transgenic tomato plants increases the risk of hydraulic failure
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-09
    Laurent J. Lamarque; Sylvain Delzon; Haley Toups; Anne‐Isabelle Gravel; Déborah Corso; Eric Badel; Régis Burlett; Guillaume Charrier; Hervé Cochard; Steven Jansen; Andrew King; José M. Torres‐Ruiz; Jérôme Pouzoulet; Grant R. Cramer; Andrew J. Thompson; Gregory A. Gambetta

    Climate change threatens food security, and plant science researchers have investigated methods of sustaining crop yield under drought. One approach has been to overproduce abscisic acid (ABA) to enhance water use efficiency. However, the concomitant effects of ABA overproduction on plant vascular system functioning are critical as it influences vulnerability to xylem hydraulic failure. We investigated these effects by comparing physiological and hydraulic responses to water deficit between a tomato (Solanum lycopersicum) wild type control (WT) and a transgenic line overproducing ABA (sp12). Under well‐watered conditions, the sp12 line displayed similar growth rate and greater water use efficiency by operating at lower maximum stomatal conductance. X‐ray microtomography revealed that sp12 was significantly more vulnerable to xylem embolism, resulting in a reduced hydraulic safety margin. We also observed a significant ontogenic effect on vulnerability to xylem embolism for both WT and sp12. This study demonstrates that the greater water use efficiency in the tomato ABA overproducing line is associated with higher vulnerability of the vascular system to embolism and a higher risk of hydraulic failure. Integrating hydraulic traits into breeding programmes represents a critical step for effectively managing a crop's ability to maintain hydraulic conductivity and productivity under water deficit.

    更新日期:2020-01-11
  • A point mutation in LTT1 enhances cold tolerance at the booting stage in rice
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-10
    Yufang Xu; Ruci Wang; Yueming Wang; Li Zhang; Shanguo Yao

    The cold tolerance of rice at the booting stage is a main factor determining sustainability and regional adaptability. However, relatively few cold tolerance genes have been identified that can be effectively used in breeding programs. Here, we show that a point mutation in the low‐temperature tolerance 1 (LTT1) gene improves cold tolerance by maintaining tapetum degradation and pollen development, by activation of systems that metabolise reactive oxygen species (ROS). Cold‐induced ROS accumulation is therefore prevented in the anthers of the ltt1 mutants allowing correct development. In contrast, exposure to cold stress dramatically increases ROS accumulation in the wild type (WT) anthers, together with the expression of genes encoding proteins associated with programmed cell death (PCD) and with the accelerated degradation of the tapetum that ultimately leads to pollen abortion. These results demonstrate that appropriate ROS management is critical for the cold tolerance of rice at the booting stage. Hence, the ltt1 mutation can significantly improve the seed setting ability of cold‐sensitive rice varieties under low temperature stress conditions, with little yield penalty under optimal temperature conditions. This study highlights the importance of a valuable genetic resource that may be applied in rice breeding programs to enhance cold tolerance.

    更新日期:2020-01-11
  • Protein phosphatase 2A alleviates cadmium toxicity by modulating ethylene production in Arabidopsis thaliana
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-09
    Jie Chen; Xue Wang; Wenwen Zhang; Shuqun Zhang; Fang‐Jie Zhao

    Cadmium (Cd) is phytotoxic and detoxified primarily via phytochelatin (PC) complexation in Arabidopsis. Here, we explore Cd toxicity responses and defense mechanisms beyond the PC pathway using forward genetics approach. We isolated an Arabidopsis thaliana Cd‐hypersensitive mutant, Cd‐induced short root 1 (cdsr1) in the PC synthase mutant (cad1‐3) background. Using genomic resequencing and complementation, we identified PP2A‐4C as the causal gene for the mutant phenotype, which encodes a catalytic subunit of protein phosphatase 2A (PP2A). Root and shoot growth of cdsr1 cad1‐3 and cdsr1 were more sensitive to Cd than their respective wild type cad1‐3 and Col‐0. A mutant of the PP2A scaffolding subunit 1A was also more sensitive to Cd. PP2A‐4C was localized in the cytoplasm and nucleus and PP2A‐4C expression was downregulated by Cd in cad1‐3. PP2A enzyme activity was decreased in cdsr1 and cdsr1 cad1‐3 under Cd stress. The expression of 1‐aminocyclopropane‐1‐carboxylic acid synthase genes ACS2 and ACS6 was upregulated by Cd more in cad1‐3 and cdsr1 cad1‐3 than in Col‐0 and the double mutant had a higher ACS activity. cdsr1 cad1‐3 and cdsr1 overproduced ethylene under Cd stress. The results suggest that PP2A containing 1A and 4C subunits alleviates Cd‐induced growth inhibition by modulating ethylene production.

    更新日期:2020-01-09
  • Rhizosphere modelling reveals spatiotemporal distribution of daidzein shaping soybean rhizosphere bacterial community
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-02
    Fuki Okutani; Shoichiro Hamamoto; Yuichi Aoki; Masaru Nakayasu; Naoto Nihei; Taku Nishimura; Kazufumi Yazaki; Akifumi Sugiyama

    Plant roots nurture a wide variety of microbes via exudation of metabolites, shaping the rhizosphere's microbial community. Despite the importance of plant specialized metabolites in the assemblage and function of microbial communities in the rhizosphere, little is known of how far the effects of these metabolites extend through the soil. We employed a fluid model to simulate the spatiotemporal distribution of daidzein, an isoflavone secreted from soybean roots, and validated using soybeans grown in a rhizobox. We then analysed how daidzein affects bacterial communities using soils artificially treated with daidzein. Simulation of daidzein distribution showed that it was only present within a few millimetres of root surfaces. After 14 days in a rhizobox, daidzein was only present within 2 mm of root surfaces. Soils with different concentrations of daidzein showed different community composition, with reduced α‐diversity in daidzein‐treated soils. Bacterial communities of daidzein‐treated soils were closer to those of the soybean rhizosphere than those of bulk soils. This study highlighted the limited distribution of daidzein within a few millimetres of root surfaces and demonstrated a novel role of daidzein in assembling bacterial communities in the rhizosphere by acting as more of a repellant than an attractant.

    更新日期:2020-01-04
  • A mycorrhiza‐specific H+‐ATPase is essential for arbuscule development and symbiotic phosphate and nitrogen uptake
    Plant Cell Environ. (IF 5.624) Pub Date : 2020-01-03
    Junli Liu; Jiadong Chen; Kun Xie; Yuan Tian; Anning Yan; Jianjian Liu; Yujuan Huang; Shuangshuang Wang; Yiyong Zhu; Aiqun Chen; Guohua Xu

    Most land plants can form symbiosis with arbuscular mycorrhizal (AM) fungi to enhance uptake of mineral nutrients, particularly phosphate (Pi) and nitrogen (N), from the soil. It is established that transport of Pi from interfacial apoplast into plant cells depends on the H+ gradient generated by the H+‐ATPase located on the periarbuscular membrane (PAM), however, little evidence regarding the potential link between mycorrhizal N transport and H+‐ATPase activity is available to date. Here, we report that a PAM‐localized tomato H+‐ATPase, SlHA8, is indispensable for arbuscule development and mycorrhizal P and N uptake. Knockout of SlHA8 resulted in truncated arbuscule morphology, reduced shoot P and N accumulation, and decreased H+‐ATPase activity and acidification of apoplastic spaces in arbusculated cells. Overexpression of SlHA8 in tomato promoted both P and N uptake, and increased total colonization level, but did not affect arbuscule morphology. Heterogeneous expression of SlHA8 in the rice osha1 mutant could fully complement its defects in arbuscule development and mycorrhizal P and N uptake. Our results propose a pivotal role of the SlHA8 in energizing both the symbiotic P and N transport, and highlight the evolutionary conservation of the AM‐specific H+‐ATPase orthologs in maintaining AM symbiosis across different mycorrhizal plant species.

    更新日期:2020-01-04
  • Comparative genome and transcriptome analysis unravels key factors of nitrogen use efficiency in Brassica napus L
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-30
    Quan Li; Guangda Ding; Ningmei Yang; Philip John White; Xiangsheng Ye; Hongmei Cai; Jianwei Lu; Lei Shi; Fangsen Xu

    Considerable genetic variation in agronomic nitrogen (N) use efficiency (NUE) has been reported among genotypes of Brassica napus. However, the physiological and molecular mechanisms underpinning these differences remain poorly understood. In this study, physiological and genetic factors impacting NUE were identified in field trials and hydroponic experiments using two B. napus genotypes with contrasting NUE. The results showed that the N‐efficient genotype (D4‐15) had greater N uptake and utilization efficiencies, more root tips, larger root surface and root volume, and higher N assimilation and photosynthesis capacity than the N‐inefficient genotype (D2‐1). Genomic analysis revealed that D4‐15 had a greater genome diversity related to NUE than D2‐1. By combining genomic and transcriptomic analysis, genes involved in photosynthesis and C/N metabolism were implicated in conferring NUE. Co‐expression network analysis of genes that differed between the two genotypes suggested gene clusters impacting NUE. A nitrate transporter gene BnaA06g04560D (NRT2.1) and two vacuole nitrate transporter CLC genes (BnaA02g11800D and BnaA02g28670D) were up‐regulated by N starvation in D4‐15 but not in D2‐1. The study revealed that high N uptake and utilization efficiencies, maintained photosynthesis and coordinated C/N metabolism confer high NUE in B. napus, and identified candidate genes that could facilitate breeding for enhanced NUE in B. napus.

    更新日期:2019-12-31
  • Genetic components of root architecture and anatomy adjustments to water‐deficit stress in spring barley
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-30
    Benedict C. Oyiga; Janina Palczak; Tobias Wojciechowski; Jonathan P. Lynch; Ali A Naz; Jens Léon; Agim Ballvora

    Roots perform vital roles for adaptation and productivity under water‐deficit stress, even though their specific functions are poorly understood. In this study, the genetic control of the nodal‐root architectural and anatomical response to water deficit were investigated among diverse spring barley accessions. Water deficit induced substantial variations in the nodal root traits. The cortical, stele, and total root cross‐sectional areas of the main‐shoot nodal roots decreased under water deficit, but increased in the tiller nodal roots. Root xylem density and arrested nodal roots increased under water deficit, with the formation of root suberization/lignification and large cortical aerenchyma. Genome‐wide association study implicated 11 QTL intervals in the architectural and anatomical nodal root response to water deficit. Among them, three and four QTL intervals had strong effects across seasons and on both root architectural and anatomical traits, respectively. Genome‐wide epistasis analysis revealed 44 epistatically interacting SNP loci. Further analyses showed that these QTL intervals contain important candidate genes, including ZIFL2, MATE, and PPIB, whose functions are shown to be related to the root adaptive response to water deprivation in plants. These results give novel insight into the genetic architectures of barley nodal root response to soil water deficit stress in the fields, and thus offer useful resources for root‐targeted marker‐assisted selection.

    更新日期:2019-12-31
  • Abscisic acid‐triggered guard cell l‐cysteine desulfhydrase function and in situ hydrogen sulfide production contributes to heme oxygenase‐modulated stomatal closure
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-30
    Jing Zhang; Mingjian Zhou; Zhenglin Ge; Jie Shen; Can Zhou; Cecilia Gotor; Luis C. Romero; Xingliang Duan; Xin Liu; Deliang Wu; Xianchao Yin; Yanjie Xie

    Recent studies have demonstrated that hydrogen sulfide (H2S) produced through the activity of l‐cysteine desulfhydrase (DES1) is an important gaseous signaling molecule in plants that could participate in abscisic acid (ABA)‐induced stomatal closure. However, the coupling of the DES1/H2S signaling pathways to guard cell movement has not been thoroughly elucidated. The results presented here provide genetic evidence for a physiologically relevant signaling pathway that governs guard cell in situ DES1/H2S function in stomatal closure. We discovered that ABA‐activated DES1 produces H2S in guard cells. The impaired guard cell ABA phenotype of the des1 mutant can be fully complemented when DES1/H2S function has been specifically rescued in guard cells and epidermal cells, but not mesophyll cells. This research further characterized DES1/H2S function in the regulation of LONG HYPOCOTYL1 (HY1, a member of the heme oxygenase family) signaling. ABA‐induced DES1 expression and H2S production are hyper‐activated in the hy1 mutant, both of which can be fully abolished by the addition of H2S scavenger. Impaired guard cell ABA phenotype of des1/hy1 can be restored by H2S donors. Taken together, this research indicated that guard cell in situ DES1 function is involved in ABA‐induced stomatal closure, which also acts as a pivotal hub in regulating HY1 signaling.

    更新日期:2019-12-31
  • Carbon starvation reduces carbohydrate and anthocyanin accumulation in red‐fleshed fruit via trehalose 6‐phosphate and MYB27
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-30
    Simona Nardozza; Helen L. Boldingh; M. Peggy Kashuba; Regina Feil; Dan Jones; Amali H. Thrimawithana; Hilary S. Ireland; Marine Philippe; Mark W. Wohlers; Tony K. McGhie; Mirco Montefiori; John E. Lunn; Andrew C. Allan; Annette C. Richardson

    Kiwifruit (Actinidia spp.) is a recently domesticated fruit crop with several novel‐coloured cultivars being developed. Achieving uniform fruit flesh pigmentation in red genotypes is challenging. To investigate the cause of colour variation between fruits, we focused on a red‐fleshed Actinidia chinensis var. chinensis genotype. It was hypothesized that carbohydrate supply could be responsible for this variation. Early in fruit development, we imposed high or low (carbon starvation) carbohydrate supplies treatments; carbohydrate import or redistribution was controlled by applying a girdle at the shoot base. Carbon starvation affected fruit development as well as anthocyanin and carbohydrate metabolite concentrations, including the signalling molecule trehalose 6‐phosphate. RNA‐Seq analysis showed down‐regulation of both gene‐encoding enzymes in the anthocyanin and carbohydrate biosynthetic pathways. The catalytic trehalose 6‐phosphate synthase gene TPS1.1a was down‐regulated, whereas putative regulatory TPS7 and TPS11 were strongly up‐regulated. Unexpectedly, under carbon starvation MYB10, the anthocyanin pathway regulatory activator was slightly up‐regulated, whereas MYB27 was also up‐regulated and acts as a repressor. To link these two metabolic pathways, we propose a model where trehalose 6‐phosphate and the active repressor MYB27 are involved in sensing the carbon starvation status. This signals the plant to save resources and reduce the production of anthocyanin in fruits.

    更新日期:2019-12-31
  • Genome‐wide association study reveals new genes involved in leaf trichome formation in polyploid oilseed rape (Brassica napus L.)
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-30
    Lijie Xuan; Tao Yan; Lingzhi Lu; Xinze Zhao; Dezhi Wu; Shuijin Hua; Lixi Jiang

    Leaf trichomes protect against various biotic and abiotic stresses in plants. However, there is little knowledge about this trait in oilseed rape (Brassica napus). Here, we demonstrated that hairy leaves were less attractive to Plutella xylostella larvae than glabrous leaves. We established a core germplasm collection with 290 accessions for a genome‐wide association study (GWAS) of the leaf trichome trait in oilseed rape. We compared the transcriptomes of the shoot apical meristem (SAM) between hairy‐ and glabrous‐leaf genotypes to narrow down the candidate genes identified by GWAS. The single nucleotide polymorphisms and the different transcript levels of BnaA.GL1.a, BnaC.SWEET4.a, BnaC.WAT1.a and BnaC.WAT1.b corresponded to the divergence of the hairy‐ and glabrous‐leaf phenotypes, indicating the role of sugar and/or auxin signalling in leaf trichome initiation. The hairy‐leaf SAMs had lower glucose and sucrose contents but higher expression of putative auxin responsive factors than the glabrous‐leaf SAMs. Spraying of exogenous auxin (8 μm) increased leaf trichome number in certain genotypes, whereas spraying of sucrose (1%) plus glucose (6%) slightly repressed leaf trichome initiation. These data contribute to the existing knowledge about the genetic control of leaf trichomes and would assist breeding towards the desired leaf surface type in oilseed rape.

    更新日期:2019-12-31
  • The diversity of soil microbial communities matters when legumes face drought
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-29
    Marion Prudent; Samuel Dequiedt; Camille Sorin; Sylvie Girodet; Virginie Nowak; Gérard Duc; Christophe Salon; Pierre‐Alain Maron

    The cultivation of legumes shows promise for the development of sustainable agriculture but yield instability remains one of the main obstacles for its adoption. Here we tested whether the yield stability (i.e resistance and resilience) of pea plants subjected to drought could be enhanced by soil microbial diversity.

    更新日期:2019-12-30
  • The influence of soil temperature and water content on belowground hydraulic conductance and leaf gas exchange in mature trees of three boreal species
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-24
    Anna Lintunen; Teemu Paljakka; Yann Salmon; Roderick Dewar; Anu Riikonen; Teemu Hölttä

    Understanding stomatal regulation is fundamental to predicting the impact of changing environmental conditions on vegetation. However, the influence of soil temperature (ST) and soil water content (SWC) on canopy conductance (gs) through changes in belowground hydraulic conductance (kbg) remains poorly understood, because kbg has seldom been measured in field conditions. Our aim was to i) examine the dependence of kbg on ST and SWC, ii) examine the dependence of gs on kbg, and iii) test a recent stomatal optimization model according to which gs and soil‐to‐leaf hydraulic conductance are strongly coupled. We estimated kbg from continuous sap flow and xylem diameter measurements in three boreal species. kbg increased strongly with increasing ST when ST was below +8°C, and typically increased with increasing SWC when ST was not limiting. gs was correlated with kbg in all three species, and modelled and measured gs were well correlated in Pinus sylvestris (a model comparison was only possible for this species). These results imply an important role for kbg in mediating linkages between the soil environment and leaf gas exchange. In particular, our finding that ST strongly influences kbg in mature trees may help us to better understand tree behaviour in cold environments.

    更新日期:2019-12-25
  • Herbivore‐specific plant volatiles prime neighboring plants for nonspecific defense responses
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-19
    Bipana Paudel Timilsena; Irmgard Seidl‐Adams; James H. Tumlinson

    Plants produce species‐specific herbivore‐induced plant volatiles (HIPVs) after damage. We tested the hypothesis that herbivore‐specific HIPVs prime neighboring plants to induce defenses specific to the priming herbivore. Since Manduca sexta (specialist) and Heliothis virescens (generalist) herbivory induced unique HIPV profiles in Nicotiana benthamiana, we used these HIPVs to prime receiver plants for defense responses to simulated herbivory (mechanical wounding and herbivore regurgitant application). Jasmonic acid (JA) accumulations and emitted volatile profiles were monitored as representative defense responses since JA is the major plant hormone involved in wound and defense signaling and HIPVs have been implicated as signals in tritrophic interactions. Herbivore species‐specific HIPVs primed neighboring plants, which produced 2 to 4 times more volatiles and JA after simulated herbivory when compared to similarly treated constitutive volatile‐exposed plants. However, HIPV‐exposed plants accumulated similar amounts of volatiles and JA independent of the combination of priming or challenging herbivore. Furthermore, volatile profiles emitted by primed plants depended only on the challenging herbivore species but not on the species‐specific HIPV profile of damaged emitter plants. This suggests that feeding by either herbivore species primed neighboring plants for increased HIPV emissions specific to the subsequently attacking herbivore and is probably controlled by JA.

    更新日期:2019-12-20
  • Tomato roots have a functional silicon influx transporter but not a functional silicon efflux transporter
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-17
    Hao Sun; Yaoke Duan; Namiki Mitani‐Ueno; Jing Che; Jianhua Jia; Jiaqi Liu; Jia Guo; Jian Feng Ma; Haijun Gong

    Silicon (Si) accumulation in shoots differs greatly with plant species, but the molecular mechanisms for this interspecific difference are unknown. Here, we isolated homologous genes of rice Si influx (SlLsi1) and efflux (SlLsi2) transporter genes in tomato (Solanum lycopersicum L.) and functionally characterized these genes. SlLsi1 showed transport activity for Si when expressed in both rice lsi1 mutant and Xenopus laevis oocytes. SlLsi1 was constitutively expressed in the roots. Immunostaining showed that SlLsi1 was localized at the plasma membrane of both root tip and basal region without polarity. Furthermore, overexpression of SlLsi1 in tomato increased Si concentration in the roots and root cell sap but did not alter the Si concentration in the shoots. By contrast, two Lsi2‐like proteins did not show efflux transport activity for Si in Xenopus oocytes. However, when functional CsLsi2 from cucumber was expressed in tomato, the Si uptake was significantly increased, resulting in higher Si accumulation in the leaves and enhanced tolerance of the leaves to water deficit and high temperature. Our results suggest that the low Si accumulation in tomato is attributed to the lack of functional Si efflux transporter Lsi2 required for active Si uptake although SlLsi1 is functional.

    更新日期:2019-12-18
  • MiR399d and epigenetic modification comodulate anthocyanin accumulation in Malus leaves suffering from phosphorus deficiency
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-13
    Zhen Peng; Ji Tian; Rongli Luo; Yanhui Kang; Yanfen Lu; Yujing Hu; Na Liu; Jie Zhang; Hao Cheng; Shuqing Niu; Jie Zhang; Yuncong Yao

    Inorganic phosphorus (Pi) deficiency induces anthocyanin accumulation in the leaves of some plant species; however, the molecular mechanisms underlying this phenomenon have not been well characterized. Here, we showed that microRNA399d (miR399d), high‐affinity Pi transporter McPHT1;4 and McMYB10 are strongly induced in Malus leaves suffering from Pi deficiency. By culturing explants of transiently transformed plants in MS medium under conditions of Pi sufficiency and Pi deficiency, miR399d and McPHT1;4 were shown to play essential roles in the response to Pi deficiency and to play positive roles in the regulation of anthocyanin biosynthesis. Silencing of McHDA6 expression and treatment with the inhibitor trichostatin‐A suggested that the low expression of McHDA6 simultaneously reduced the transcription of McMET1 and decreased the methylation level of the McMYB10 promoter; however, the expression of McMYB10 and anthocyanin content were increased. Bimolecular fluorescence complementation and yeast two‐hybrid assays revealed that McHDA6 binds directly to McMET1 through its BAH2 and DNMT1‐RFD domains. Based on the results of our study, we propose a mechanism for the molecular regulation of anthocyanin biosynthesis, namely, the miR399d and epigenetic modification comodulation model, to explain the phenomenon in which leaves turn red under conditions of Pi deficiency.

    更新日期:2019-12-13
  • Suppression of NB‐LRR Genes by miRNAs Promotes Nitrogen‐fixing Nodule Development in Medicago truncatula
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-13
    Anita Sós‐HegedŰs; Ágota Domonkos; Tamás Tóth; Péter Gyula; Péter Kaló; György Szittya

    Plant genomes contain two major classes of innate immune receptors to recognize different pathogens. The pattern recognition receptors perceive conserved pathogen‐associated molecular patterns and the resistance genes with nucleotide‐binding (NB) and leucine‐rich repeat (LRR) domains recognize specific pathogen effectors. The precise regulation of resistance genes is important since the unregulated expression of NB‐LRR genes can inhibit growth and may result in autoimmunity in the absence of pathogen infection. It was shown that a subset of miRNAs could target NB‐LRR genes and act as an important regulator of plant immunity in the absence of pathogens.

    更新日期:2019-12-13
  • Consequences of the reduction of the PSII antenna size on the light acclimation capacity of Arabidopsis thaliana
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-13
    Ludwik W. Bielczynski; Gert Schansker; Roberta Croce

    In several systems, from plant's canopy to algal bioreactors, the decrease of the antenna size has been proposed as a strategy to increase the photosynthetic efficiency. However, still little is known about possible secondary effects of such modifications. This is particularly relevant since the modulation of the antenna size is one of the most important light acclimation responses in photosynthetic organisms. In our study, we used an Arabidopsis thaliana mutant (dLhcb2) which has a 60% decrease of Lhcb1 and Lhcb2, the two main components of the major PSII antenna complex. We show that the mutant maintains the photosynthetic and photoprotective capacity of the WT and adapts to different light conditions by remodeling its photosynthetic apparatus, but the regulatory mechanism differs from that of the WT. Surprisingly, it does not compensate for the decreased light‐harvesting capacity by increasing other pigment‐protein complexes. Instead, it lowers the ratio of the cytochrome b6f and ATP synthase to the photosystems, regulating linear electron flow and maintaining the photosynthetic control at the level of these complexes as in the WT. We show that targeting the reduction of two specific antenna proteins, Lhcb1 and Lhcb2, represents a viable solution to obtain plants with a truncated antenna size, which still maintain the capacity to acclimate to different light conditions.

    更新日期:2019-12-13
  • An ectomycorrhizal fungus alters sensitivity to jasmonate, salicylate, gibberellin, and ethylene in host roots
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-13
    Veronica Basso; Annegret Kohler; Shingo Miyauchi; Vasanth Singan; Frédéric Guinet; Jan Šimura; OndŘej Novák; Kerrie W. Barry; Mojgan Amirebrahimi; Jonathan Block; Yohann Daguerre; Hyunsoo Na; Igor V. Grigoriev; Francis Martin; Claire Veneault‐Fourrey

    The phytohormones jasmonate, gibberellin, salicylate, and ethylene regulate an interconnected reprogramming network integrating root development with plant responses against microbes. The establishment of mutualistic ectomycorrhizal symbiosis requires the suppression of plant defense responses against fungi as well as the modification of root architecture and cortical cell wall properties. Here, we investigated the contribution of phytohormones and their crosstalk to the ontogenesis of ectomycorrhizae (ECM) between grey poplar (Populus tremula x alba) roots and the fungus Laccaria bicolor. To obtain the hormonal blueprint of developing ECM, we quantified the concentrations of jasmonates, gibberellins, and salicylate via liquid chromatography‐tandem mass spectrometry. Subsequently, we assessed root architecture, mycorrhizal morphology, and gene expression levels (RNA‐sequencing) in phytohormone‐treated poplar lateral roots in the presence or absence of L. bicolor. Salicylic acid accumulated in mid‐stage ECM. Exogenous phytohormone treatment affected the fungal colonization rate and/or frequency of Hartig net formation. Colonized lateral roots displayed diminished responsiveness to jasmonate but regulated some genes, implicated in defense and cell wall remodeling, that were specifically differentially expressed after jasmonate treatment. Responses to salicylate, gibberellin, and ethylene were enhanced in ECM. The dynamics of phytohormone accumulation and response suggest that jasmonate, gibberellin, salicylate, and ethylene signaling play multifaceted roles in poplar‐L. bicolor ectomycorrhizal development.

    更新日期:2019-12-13
  • A multidrug and toxic compound extrusion (MATE) transporter modulates auxin levels in root to regulate root development and promotes aluminium tolerance
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-10
    Neha Upadhyay, Debojyoti Kar, Sourav Datta

    MATE (multidrug and toxic compound extrusion) transporters play multiple roles in plants including detoxification, secondary metabolite transport, aluminium (Al) tolerance, and disease resistance. Here we identify and characterize the role of the Arabidopsis MATE transporter DETOXIFICATION30. AtDTX30 regulates auxin homeostasis in Arabidopsis roots to modulate root development and Al‐tolerance. DTX30 is primarily expressed in roots and localizes to the plasma membrane of root epidermal cells including root hairs. dtx30 mutants exhibit reduced elongation of the primary root, root hairs, and lateral roots. The mutant seedlings accumulate more auxin in their root tips indicating role of DTX30 in maintaining auxin homeostasis in the root. Al induces DTX30 expression and promotes its localization to the distal transition zone. dtx30 seedlings accumulate more Al in their roots but are hyposensitive to Al‐mediated rhizotoxicity perhaps due to saturation in root growth inhibition. Increase in expression of ethylene and auxin biosynthesis genes in presence of Al is absent in dtx30. The mutants exude less citrate under Al conditions, which might be due to misregulation of AtSTOP1 and the citrate transporter AtMATE. In conclusion, DTX30 modulates auxin levels in root to regulate root development and in the presence of Al indirectly modulates citrate exudation to promote Al tolerance.

    更新日期:2019-12-11
  • Elevated [CO2] alleviates the impacts of water deficit on xylem anatomy and hydraulic properties of maize stems
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-09
    Junzhou Liu, Shaozhong Kang, William J. Davies, Risheng Ding

    Plants can modify xylem anatomy and hydraulic properties to adjust to water status. Elevated [CO2] can increase plant water potential via reduced stomatal conductance and water loss. This raises the question of whether elevated [CO2], which thus improves plant water status, will reduce the impacts of soil water deficit on xylem anatomy and hydraulic properties of plants. To analyse the impacts of water and [CO2] on maize stem xylem anatomy and hydraulic properties, we exposed potted maize plants to varying [CO2] levels (400, 700, 900, and 1,200 ppm) and water levels (full irrigation and deficit irrigation). Results showed that at current [CO2], vessel diameter, vessel roundness, stem cross‐section area, specific hydraulic conductivity, and vulnerability to embolism decreased under deficit irrigation; yet, these impacts of deficit irrigation were reduced at elevated [CO2]. Across all treatments, midday stem water potential was tightly correlated with xylem traits and displayed similar responses. A distinct trade‐off between efficiency and safety in stem xylem water transportation in response to water deficit was observed at current [CO2] but not observed at elevated [CO2]. The results of this study enhance our knowledge of plant hydraulic acclimation under future climate environments and provide insights into trade‐offs in xylem structure and function.

    更新日期:2019-12-11
  • Protein lysine methylation contributes to modulating the response of sensitive and tolerant Arabidopsis species to cadmium stress
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-08
    Nelson B. C. Serre, Manon Sarthou, Océane Gigarel, Sylvie Figuet, Massimiliano Corso, Justine Choulet, Valérie Rofidal, Claude Alban, Véronique Santoni, Jacques Bourguignon, Nathalie Verbruggen, Stéphane Ravanel

    The mechanisms underlying the response and adaptation of plants to excess of trace elements are not fully described. Here, we analysed the importance of protein lysine methylation for plants to cope with cadmium. We analysed the effect of cadmium on lysine‐methylated proteins and protein lysine methyltransferases (KMTs) in two cadmium‐sensitive species, Arabidopsis thaliana and A. lyrata, and in three populations of A. halleri with contrasting cadmium accumulation and tolerance traits. We showed that some proteins are differentially methylated at lysine residues in response to Cd and that a few genes coding KMTs are regulated by cadmium. Also, we showed that 9 out of 23 A. thaliana mutants disrupted in KMT genes have a tolerance to cadmium that is significantly different from that of wild‐type seedlings. We further characterized two of these mutants, one was knocked out in the calmodulin lysine methyltransferase gene and displayed increased tolerance to cadmium, and the other was interrupted in a KMT gene of unknown function and showed a decreased capacity to cope with cadmium. Together, our results showed that lysine methylation of non‐histone proteins is impacted by cadmium and that several methylation events are important for modulating the response of Arabidopsis plants to cadmium stress.

    更新日期:2019-12-09
  • Photosystem II antenna complexes CP26 and CP29 are essential for nonphotochemical quenching in Chlamydomonas reinhardtii
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-08
    Stefano Cazzaniga, Minjae Kim, Francesco Bellamoli, Jooyoen Jeong, Sangmuk Lee, Federico Perozeni, Andrea Pompa, EonSeon Jin, Matteo Ballottari

    Photosystems must balance between light harvesting to fuel the photosynthetic process for CO2 fixation and mitigating the risk of photodamage due to absorption of light energy in excess. Eukaryotic photosynthetic organisms evolved an array of pigment‐binding proteins called light harvesting complexes constituting the external antenna system in the photosystems, where both light harvesting and activation of photoprotective mechanisms occur. In this work, the balancing role of CP29 and CP26 photosystem II antenna subunits was investigated in Chlamydomonas reinhardtii using CRISPR‐Cas9 technology to obtain single and double mutants depleted of monomeric antennas. Absence of CP26 and CP29 impaired both photosynthetic efficiency and photoprotection: Excitation energy transfer from external antenna to reaction centre was reduced, and state transitions were completely impaired. Moreover, differently from higher plants, photosystem II monomeric antenna proteins resulted to be essential for photoprotective thermal dissipation of excitation energy by nonphotochemical quenching.

    更新日期:2019-12-09
  • Herbivore exposure alters ion fluxes and improves salt tolerance in a desert shrub
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-06
    Yingying Chen, Chuanjian Cao, Zhujuan Guo, Qinghua Zhang, Shuwen Li, Xiao Zhang, Junqing Gong, Yingbai Shen

    Plants have evolved complex mechanisms that allow them to withstand multiple environmental stresses, including biotic and abiotic stresses. Here, we investigated the interaction between herbivore exposure and salt stress of Ammopiptanthus nanus, a desert shrub. We found that jasmonic acid (JA) was involved in plant responses to both herbivore attack and salt stress, leading to an increased NaCl stress tolerance for herbivore‐pretreated plants and increase in K+/Na+ ratio in roots. Further evidence revealed the mechanism by which herbivore improved plant NaCl tolerance. Herbivore pretreatment reduced K+ efflux and increased Na+ efflux in plants subjected to long‐term, short‐term, or transient NaCl stress. Moreover, herbivore pretreatment promoted H+ efflux by increasing plasma membrane H+‐adenosine triphosphate (ATP)ase activity. This H+ efflux creates a transmembrane proton motive force that drives the Na+/H+ antiporter to expel excess Na+ into the external medium. In addition, high cytosolic Ca2+ was observed in the roots of herbivore‐treated plants exposed to NaCl, and this effect may be regulated by H+‐ATPase. Taken together, herbivore exposure enhances A. nanus tolerance to salt stress by activating the JA‐signalling pathway, increasing plasma membrane H+‐ATPase activity, promoting cytosolic Ca2+ accumulation, and then restricting K+ leakage and reducing Na+ accumulation in the cytosol.

    更新日期:2019-12-07
  • Comparative metabolomics implicates threitol as a fungal signal supporting colonization of Armillaria luteobubalina on eucalypt roots
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-03
    Johanna W.‐H. Wong, Krista L. Plett, Siria H.A. Natera, Ute Roessner, Ian C. Anderson, Jonathan M. Plett

    Armillaria root rot is a fungal disease that affects a wide range of trees and crops around the world. Despite being a widespread disease, little is known about the plant molecular responses towards the pathogenic fungi at the early phase of their interaction. With recent research highlighting the vital roles of metabolites in plant root–microbe interactions, we sought to explore the presymbiotic metabolite responses of Eucalyptus grandis seedlings towards Armillaria luteobuablina, a necrotrophic pathogen native to Australia. Using a metabolite profiling approach, we have identified threitol as one of the key metabolite responses in E. grandis root tips specific to A. luteobubalina that were not induced by three other species of soil‐borne microbes of different lifestyle strategies (a mutualist, a commensalist, and a hemi‐biotrophic pathogen). Using isotope labelling, threitol detected in the Armillaria‐treated root tips was found to be largely derived from the fungal pathogen. Exogenous application of d‐threitol promoted microbial colonization of E. grandis and triggered hormonal responses in root cells. Together, our results support a role of threitol as an important metabolite signal during eucalypt‐Armillaria interaction prior to infection thus advancing our mechanistic understanding on the earliest stage of Armillaria disease development.

    更新日期:2019-12-04
  • The 18O‐signal transfer from water vapour to leaf water and assimilates varies among plant species and growth forms
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-03
    Marco M. Lehmann, Gregory R. Goldsmith, Cathleen Mirande‐Ney, Rosemarie B. Weigt, Leonie Schönbeck, Ansgar Kahmen, Arthur Gessler, Rolf T.W. Siegwolf, Matthias Saurer

    The 18O signature of atmospheric water vapour (δ18OV) is known to be transferred via leaf water to assimilates. It remains, however, unclear how the 18O‐signal transfer differs among plant species and growth forms. We performed a 9‐hr greenhouse fog experiment (relative humidity ≥ 98%) with 18O‐depleted water vapour (−106.7‰) on 140 plant species of eight different growth forms during daytime. We quantified the 18O‐signal transfer by calculating the mean residence time of O in leaf water (MRTLW) and sugars (MRTSugars) and related it to leaf traits and physiological drivers. MRTLW increased with leaf succulence and thickness, varying between 1.4 and 10.8 hr. MRTSugars was shorter in C3 and C4 plants than in crassulacean acid metabolism (CAM) plants and highly variable among species and growth forms; MRTSugars was shortest for grasses and aquatic plants, intermediate for broadleaf trees, shrubs, and herbs, and longest for conifers, epiphytes, and succulents. Sucrose was more sensitive to δ18OV variations than other assimilates. Our comprehensive study shows that plant species and growth forms vary strongly in their sensitivity to δ18OV variations, which is important for the interpretation of δ18O values in plant organic material and compounds and thus for the reconstruction of climatic conditions and plant functional responses.

    更新日期:2019-12-04
  • A polerovirus, Potato leafroll virus, alters plant–vector interactions using three viral proteins
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-02
    MacKenzie F. Patton, Aurélie Bak, Jordan M. Sayre, Michelle L. Heck, Clare L. Casteel

    Potato leafroll virus (PLRV), genus Polerovirus, family Luteoviridae, is a major pathogen of potato worldwide. PLRV is transmitted among host plants by aphids in a circulative–nonpropagative manner. Previous studies have demonstrated that PLRV infection increases aphid fecundity on, and attraction to, infected plants as compared to controls. However, the molecular mechanisms mediating this relationship are still poorly understood. In this study, we measured the impact of PLRV infection on plant–aphid interactions and plant chemistry in two hosts: Solanum tuberosum and Nicotiana benthamiana. Our study demonstrates that PLRV infection attenuates the induction of aphid‐induced jasmonic acid and ethylene in S. tuberosum and N. benthamiana. Using transient expression experiments, insect bioassays and chemical analysis, we show that expression of three PLRV proteins (P0, P1, and P7) mediate changes in plant–aphid interactions and inhibition of aphid‐induced jasmonic acid and ethylene in N. benthamiana. This study enhances our understanding of the plant‐vector‐pathogen interface by elucidating new mechanisms by which plant viruses transmitted in a circulative manner can manipulate plant hosts.

    更新日期:2019-12-03
  • A NAC‐type transcription factor confers aluminium resistance by regulating cell wall‐associated receptor kinase 1 and cell wall pectin
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-02
    He Qiang Lou, Wei Fan, Jian Feng Jin, Jia Meng Xu, Wei Wei Chen, Jian Li Yang, Shao Jian Zheng

    Transcriptional regulation is important for plants to respond to toxic effects of aluminium (Al). However, our current knowledge to these events is confined to a few transcription factors. Here, we functionally characterized a rice bean (Vigna umbellata) NAC‐type transcription factor, VuNAR1, in terms of Al stress response. We demonstrated that rice bean VuNAR1 is a nuclear‐localized transcriptional activator, whose expression was specifically upregulated by Al in roots but not in shoot. VuNAR1 overexpressing Arabidopsis plants exhibit improved Al resistance via Al exclusion. However, VuNAR1‐mediated Al exclusion is independent of the function of known Al‐resistant genes. Comparative transcriptomic analysis revealed that VuNAR1 specifically regulates the expression of genes associated with protein phosphorylation and cell wall modification in Arabidopsis. Transient expression assay demonstrated the direct transcriptional activation of cell wall‐associated receptor kinase 1 (WAK1) by VuNAR1. Moreover, yeast one‐hybrid assays and MEME motif searches identified a new VuNAR1‐specific binding motif in the promoter of WAK1. Compared with wild‐type Arabidopsis plants, VuNAR1 overexpressing plants have higher WAK1 expression and less pectin content. Taken together, our results suggest that VuNAR1 regulates Al resistance by regulating cell wall pectin metabolism via directly binding to the promoter of WAK1 and induce its expression.

    更新日期:2019-12-03
  • Deterioration of ovary plays a key role in heat stress‐induced spikelet sterility in sorghum
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-01
    Anuj Chiluwal, Raju Bheemanahalli, Vinutha Kanaganahalli, Dan Boyle, Ramasamy Perumal, Meghnath Pokharel, Halilou Oumarou, S.V. Krishna Jagadish

    In sorghum (Sorghum bicolor [L.] Moench), the impact of heat stress during flowering on seed set is known, but mechanisms that lead to tolerance are not known. A diverse set of sorghum genotypes was tested under controlled environment and field conditions to ascertain the impact of heat stress on time‐of‐day of flowering, pollen viability, and ovarian tissue. A highly conserved early morning flowering was observed, wherein >90% of spikelets completed flowering within 30 min after dawn, both in inbreds and hybrids. A strong quantitative impact of heat stress was recorded before pollination (reduced pollen viability) and post pollination (reduced pollen tube growth and linear decline in fertility). Although viable pollen tube did reach the micropylar region, 100% spikelet sterility was recorded under 40/22°C (day/night temperatures), even in the tolerant genotype Macia. Heat stress induced significant damage to the ovarian tissue near the micropylar region, leading to highly condensed cytoplasmic contents and disintegrated nucleolus and nucleus in the susceptible genotype RTx430. Whereas, relatively less damages to ovarian cell organelles were observed in the tolerant genotype Macia under heat stress. Integrating higher tolerance in female reproductive organ will help in effective utilization of the early morning flowering mechanism to enhance sorghum productivity under current and future hotter climate.

    更新日期:2019-12-02
  • High night temperature induced changes in grain starch metabolism alters starch, protein, and lipid accumulation in winter wheat
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-01
    Somayanda M. Impa, Amaranatha R. Vennapusa, Raju Bheemanahalli, David Sabela, Dan Boyle, Harkamal Walia, S.V. Krishna Jagadish

    Unlike sporadic daytime heat spikes, a consistent increase in night‐time temperatures can potentially derail the genetic gains being achieved. Ten winter wheat genotypes were exposed to six different night‐time temperatures (15–27°C) during flowering and grain‐filling stages in controlled environment chambers. We identified the night‐time temperature of 23oC as the critical threshold beyond which a consistent decline in yields and quality was observed. Confocal laser scanning micrographs of central endosperm, bran, and germ tissue displayed differential accumulation of protein, lipid, and starch with increasing night‐time temperatures. KS07077M‐1 recorded a decrease in starch and an increase in protein and lipid in central endosperm with increasing night‐time temperatures, whereas the same was significantly lower in the tolerant SY Monument. Expression analysis of genes encoding 21 enzymes (including isoforms) involved in grain–starch metabolism in developing grains revealed a high night‐time temperature (HNT)‐induced reduction in transcript levels of adenosine diphosphate glucose pyrophosphorylase small subunit involved in starch synthesis and a ≥2‐fold increase in starch degrading enzymes isoamylase III, alpha‐, and beta‐amylase. The identified critical threshold, grain compositional changes, and the key enzymes in grain starch metabolism that lead to poor starch accumulation in grains establish the foundational knowledge for enhancing HNT tolerance in wheat.

    更新日期:2019-12-02
  • Pyrenoidal sequestration of cadmium impairs carbon dioxide fixation in a microalga
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-01
    Florent Penen, Marie‐Pierre Isaure, Dirk Dobritzsch, Hiram Castillo‐Michel, Etienne Gontier, Philippe Le Coustumer, Julien Malherbe, Dirk Schaumlöffel

    Mixotrophic microorganisms are able to use organic carbon as well as inorganic carbon sources and thus, play an essential role in the biogeochemical carbon cycle. In aquatic ecosystems, the alteration of carbon dioxide (CO2) fixation by toxic metals such as cadmium – classified as a priority pollutant – could contribute to the unbalance of the carbon cycle. In consequence, the investigation of cadmium impact on carbon assimilation in mixotrophic microorganisms is of high interest. We exposed the mixotrophic microalga Chlamydomonas reinhardtii to cadmium in a growth medium containing both CO2 and labelled 13C‐[1,2] acetate as carbon sources. We showed that the accumulation of cadmium in the pyrenoid, where it was predominantly bound to sulphur ligands, impaired CO2 fixation to the benefit of acetate assimilation. Transmission electron microscopy (TEM)/X‐ray energy dispersive spectroscopy (X‐EDS) and micro X‐ray fluorescence (μXRF)/micro X‐ray absorption near‐edge structure (μXANES) at Cd LIII‐edge indicated the localization and the speciation of cadmium in the cellular structure. In addition, nanoscale secondary ion mass spectrometry (NanoSIMS) analysis of the 13C/12C ratio in pyrenoid and starch granules revealed the origin of carbon sources. The fraction of carbon in starch originating from CO2 decreased from 73 to 39% during cadmium stress. For the first time, the complementary use of high‐resolution elemental and isotopic imaging techniques allowed relating the impact of cadmium at the subcellular level with carbon assimilation in a mixotrophic microalga.

    更新日期:2019-12-02
  • Light‐ and temperature‐entrainable circadian clock in soybean development
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-12-01
    Yu Wang, Li Yuan, Tong Su, Qiao Wang, Ya Gao, Siyuan Zhang, Qian Jia, Guolong Yu, Yongfu Fu, Qun Cheng, Baohui Liu, Fanjiang Kong, Xiao Zhang, Chun‐Peng Song, Xiaodong Xu, Qiguang Xie

    In plants, the spatiotemporal expression of circadian oscillators provides adaptive advantages in diverse species. However, the molecular basis of circadian clock in soybean is not known. In this study, we used soybean hairy roots expression system to monitor endogenous circadian rhythms and the sensitivity of circadian clock to environmental stimuli. We discovered in experiments with constant light and temperature conditions that the promoters of clock genes GmLCLb2 and GmPRR9b1 drive a self‐sustained, robust oscillation of about 24‐h in soybean hairy roots. Moreover, we demonstrate that circadian clock is entrainable by ambient light/dark or temperature cycles. Specifically, we show that light and cold temperature pulses can induce phase shifts of circadian rhythm, and we found that the magnitude and direction of phase responses depends on the specific time of these two zeitgeber stimuli. We obtained a quadruple mutant lacking the soybean gene GmLCLa1, LCLa2, LCLb1, and LCLb2 using CRISPR, and found that loss‐of‐function of these four GmLCL orthologs leads to an extreme short‐period circadian rhythm and late‐flowering phenotype in transgenic soybean. Our study establishes that the morning‐phased GmLCLs genes act constitutively to maintain circadian rhythmicity and demonstrates that their absence delays the transition from vegetative growth to reproductive development.

    更新日期:2019-12-02
  • Comparative spatial lipidomics analysis reveals cellular lipid remodelling in different developmental zones of barley roots in response to salinity
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-29
    Lenin D. Sarabia, Berin A. Boughton, Thusitha Rupasinghe, Damien L. Callahan, Camilla B. Hill, Ute Roessner

    Salinity‐induced metabolic, ionic, and transcript modifications in plants have routinely been studied using whole plant tissues, which do not provide information on spatial tissue responses. The aim of this study was to assess the changes in the lipid profiles in a spatial manner and to quantify the changes in the elemental composition in roots of seedlings of four barley cultivars before and after a short‐term salt stress. We used a combination of liquid chromatography–tandem mass spectrometry, inductively coupled plasma mass spectrometry, matrix‐assisted laser desorption/ionization mass spectrometry imaging, and reverse transcription – quantitative real time polymerase chain reaction platforms to examine the molecular signatures of lipids, ions, and transcripts in three anatomically different seminal root tissues before and after salt stress. We found significant changes to the levels of major lipid classes including a decrease in the levels of lysoglycerophospholipids, ceramides, and hexosylceramides and an increase in the levels of glycerophospholipids, hydroxylated ceramides, and hexosylceramides. Our results revealed that modifications to lipid and transcript profiles in plant roots in response to a short‐term salt stress may involve recycling of major lipid species, such as phosphatidylcholine, via resynthesis from glycerophosphocholine.

    更新日期:2019-11-30
  • Seminal roots of wild and cultivated barley differentially respond to osmotic stress in gene expression, suberization, and hydraulic conductivity
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-24
    Tino Kreszies, Stella Eggels, Victoria Kreszies, Alina Osthoff, Nandhini Shellakkutti, Jutta A. Baldauf, Viktoria V. Zeisler‐Diehl, Frank Hochholdinger, Kosala Ranathunge, Lukas Schreiber

    Wild barley, Hordeum vulgare spp. spontaneum, has a wider genetic diversity than its cultivated progeny, Hordeum vulgare spp. vulgare. Osmotic stress leads to a series of different responses in wild barley seminal roots, ranging from no changes in suberization to enhanced endodermal suberization of certain zones and the formation of a suberized exodermis, which was not observed in the modern cultivars studied so far. Further, as a response to osmotic stress, the hydraulic conductivity of roots was not affected in wild barley, but it was 2.5‐fold reduced in cultivated barley. In both subspecies, osmotic adjustment by increasing proline concentration and decreasing osmotic potential in roots was observed. RNA‐sequencing indicated that the regulation of suberin biosynthesis and water transport via aquaporins were different between wild and cultivated barley. These results indicate that wild barley uses different strategies to cope with osmotic stress compared with cultivated barley. Thus, it seems that wild barley is better adapted to cope with osmotic stress by maintaining a significantly higher hydraulic conductivity of roots during water deficit.

    更新日期:2019-11-26
  • Water and Vapor Transport in Algal‐Fungal Lichen: Modeling constrained by Laboratory Experiments, an application for Flavoparmelia caperata
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-23
    Aaron Potkay, Marie‐Claire ten Veldhuis, Ying Fan, Caio R.C. Mattos, Gennady Ananyev, G. Charles Dismukes

    Algal‐fungal symbionts share water, nutrients and gases via an architecture unique to lichens. Because lichen activity is controlled by moisture dynamics, understanding water transport is prerequisite to understanding their fundamental biology. We propose a model of water distributions within foliose lichens governed by laws of fluid motion. Our model differentiates between water stored in symbionts, on extracellular surfaces, and in distinct morphological layers. We parameterize our model with hydraulic properties inverted from laboratory measurements of Flavoparmelia caperata and validate for wetting and drying. We ask: (1) Where is the bottleneck to water transport? (2) How do hydration and dehydration dynamics differ, and (3) what causes these differences? Resistance to vapor flow is concentrated at thallus surfaces and acts as the bottleneck for equilibrium, while internal resistances are small. The model captures hysteresis in hydration and desiccation, which are shown to be controlled by nonlinearities in hydraulic capacitance. Muting existing nonlinearities slowed drying and accelerated wetting, while exaggerating nonlinearities accelerated drying and slowed wetting. The hydraulic nonlinearity of Flavoparmelia caperata is considerable, which may reflect its preference for humid and stable environments. The model establishes the physical foundation for future investigations of transport of water, gas, and sugar between symbionts.

    更新日期:2019-11-26
  • Wood allocation trade‐offs between fiber wall, fiber lumen and axial parenchyma drive drought resistance in neotropical trees
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-23
    Thomas A.J. Janssen, Teemu Hölttä, Katrin Fleischer, Kim Naudts, A. Han Dolman

    Functional relationships between wood density and measures of xylem hydraulic safety and efficiency are ambiguous, especially in wet tropical forests. In this meta‐analysis, we move beyond wood density per se and identify relationships between xylem allocated to fibers, parenchyma and vessels and measures of hydraulic safety and efficiency. We analyzed published data of xylem traits, hydraulic properties and measures of drought resistance from neotropical tree species retrieved from 346 sources. We found that xylem volume allocation to fiber walls increases embolism resistance, but at the expense of specific conductivity and sapwood capacitance. Xylem volume investment in fiber lumen increases capacitance, while investment in axial parenchyma is associated with higher specific conductivity. Dominant tree taxa from wet forests prioritize xylem allocation to axial parenchyma at the expense of fiber walls, resulting in a low embolism resistance for a given wood density and a high vulnerability to drought‐induced mortality. We conclude that strong trade‐offs between xylem allocation to fiber walls, fiber lumen and axial parenchyma drive drought resistance in neotropical trees. Moreover, the benefits of xylem allocation to axial parenchyma in wet tropical trees might not outweigh the consequential low embolism resistance under more frequent and severe droughts in a changing climate.

    更新日期:2019-11-26
  • Priming of inducible defenses protects Norway spruce against tree‐killing bark beetles
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-21
    Melissa H. Mageroy, Erik Christiansen, Bo Långström, Anna‐Karin Borg‐Karlson, Halvor Solheim, Niklas Björklund, Tao Zhao, Axel Schmidt, Carl Gunnar Fossdal, Paal Krokene

    Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short‐lived model plants such as Arabidopsis, but little is known about this phenomenon in long‐lived plants like spruce. We compared the effects of pretreatment with sublethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48‐year‐old Norway spruce (Picea abies) trees to mass attack by a tree‐killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees but largely avoided fungus‐inoculated trees and MeJA‐treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91‐fold higher terpene concentrations compared with untreated trees, whereas application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus‐inoculated trees is a result of direct induction of defenses, whereas resistance in MeJA‐treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.

    更新日期:2019-11-22
  • Evaluating maize phenotypic variance, heritability, and yield relationships at multiple biological scales across agronomically relevant environments
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-16
    Sarah L. Tucker, Frank G. Dohleman, Dmitry Grapov, Lex Flagel, Sean Yang, Kimberly M. Wegener, Kevin R. Kosola, Shilpa Swarup, Ryan A. Rapp, Mohamed Bedair, Steven C. Halls, Kevin C. Glenn, Michael A. Hall, Edwards Allen, Elena A. Rice

    A challenge to improve an integrative phenotype, like yield, is the interaction between the broad range of possible molecular and physiological traits that contribute to yield and the multitude of potential environmental conditions in which they are expressed. This study collected data on 31 phenotypic traits, 83 annotated metabolites, and nearly 22,000 transcripts from a set of 57 diverse, commercially relevant maize hybrids across three years in central USA corn‐belt environments. Although variability in characteristics created a complex picture of how traits interact produce yield, phenotypic traits and gene expression were more consistent across environments, while metabolite levels showed low repeatability. Phenology traits, such as green leaf number and grain moisture and whole plant nitrogen content showed the most consistent correlation with yield. A machine learning predictive analysis of phenotypic traits revealed that ear traits, phenology, and root traits were most important to predicting yield. Analysis suggested little correlation between biomass traits and yield, suggesting there is more of a sink limitation to yield under the conditions studied here. This work suggests that continued improvement of maize yields requires a strong understanding of baseline variation of plant characteristics across commercially‐relevant germplasm to drive strategies for consistently improving yield.

    更新日期:2019-11-17
  • Endophytic fungus Falciphora oryzae promotes lateral root growth by producing indole derivatives after sensing plant signals
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-14
    Xun Sun, Ning Wang, Ping Li, Zhiyan Jiang, Xiaoyu Liu, Mengcen Wang, Zhenzhu Su, Chulong Zhang, Fucheng Lin, Yan Liang

    The endophytic fungus Falciphora oryzae was initially isolated from wild rice (Oryza granulata) and colonizes many crop species and promotes plant growth. However, the molecular mechanisms underlying F. oryzae‐mediated growth promotion are still unknown. We found that F. oryzae was able to colonize Arabidopsis thaliana. The most dramatic change after F. oryzae inoculation was observed in the root architecture, as evidenced by increased lateral root growth but reduced primary root length, similar to the effect of auxin, a significant plant growth hormone. The expression of genes responsible for auxin biosynthesis, transport, and signalling was regulated in Arabidopsis roots after F. oryzae cocultivation. Indole derivatives were detected at significantly higher levels in liquid media after cocultivation compared with separate cultivation of Arabidopsis and F. oryzae. Consistently, the expression of indole biosynthetic genes was highly upregulated in F. oryzae upon treatment with Arabidopsis exudates. Global analysis of Arabidopsis gene expression at the early stage after F. oryzae cocultivation suggested that signals were exchanged to initiate Arabidopsis–F. oryzae interactions. All these results suggest that signalling molecules from Arabidopsis roots are perceived by F. oryzae and induce the biosynthesis of indole derivatives in F. oryzae, consequently stimulating Arabidopsis lateral root growth.

    更新日期:2019-11-14
  • Catalase, glutathione, and protein phosphatase 2A‐dependent organellar redox signalling regulate aphid fecundity under moderate and high irradiance
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-14
    Brwa Rasool, Barbara Karpinska, Jesús Pascual, Saijaliisa Kangasjärvi, Christine H. Foyer

    Redox processes regulate plant/insect responses, but the precise roles of environmental triggers and specific molecular components remain poorly defined. Aphid fecundity and plant responses were therefore measured in Arabidopsis thaliana mutants deficient in either catalase 2 (cat2), different protein phosphatase 2A (PP2A) subunits or glutathione (cad2, pad2, and clt1) under either moderate (250 μmol m−2 s−1) or high (800 μmol m−2 s−1) light. Aphid fecundity was decreased in pp2a‐b'γ, cat2 and the cat2 pp2a‐b'γ double mutants relative to the wild type under moderate irradiance. High light decreased aphid numbers in all genotypes except for cat2. Aphid fecundity was similar in the cat2 and glutathione‐, phytoalexin‐, and glucosinolate‐deficient cat2cad2 double mutants under both irradiances. Aphid‐induced increases in transcripts encoding the abscisic acid‐related ARABIDOPSIS ZINC‐FINGER PROTEIN 1 transcription factor were observed only under moderate light. Conversely, aphid induced increases in transcripts encoding the jasmonate‐synthesis enzyme ALLENE OXIDE CYCLASE 3 was observed in all genotypes only under high light. Aphid‐induced increases in REDOX RESPONSIVE TRANSCRIPTION FACTOR 1 mRNAs were observed in all genotypes except pp2a‐b'ζ1‐1 under both irradiances. Aphid fecundity is therefore regulated by cellular redox signalling that is mediated, at least in part, through PP2A‐dependent mitochondria to nucleus signalling pathways.

    更新日期:2019-11-14
  • Day length regulates seasonal patterns of stomatal conductance in Quercus species
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-14
    Elena Granda, Frederik Baumgarten, Arthur Gessler, Eustaquio Gil‐Pelegrin, Jose Javier Peguero‐Pina, Domingo Sancho‐Knapik, Niklaus E. Zimmerman, Víctor Resco de Dios

    Vapour pressure deficit is a major driver of seasonal changes in transpiration, but photoperiod also modulates leaf responses. Climate warming might enhance transpiration by increasing atmospheric water demand and the length of the growing season, but photoperiod‐sensitive species could show dampened responses. Here, we document that day length is a significant driver of the seasonal variation in stomatal conductance. We performed weekly gas exchange measurements across a common garden experiment with 12 oak species from contrasting geographical origins, and we observed that the influence of day length was of similar strength to that of vapour pressure deficit in driving the seasonal pattern. We then examined the generality of our findings by incorporating day‐length regulation into well‐known stomatal models. For both angiosperm and gymnosperm species, the models improved significantly when adding day‐length dependences. Photoperiod control over stomatal conductance could play a large yet underexplored role on the plant and ecosystem water balances.

    更新日期:2019-11-14
  • High porosity with tiny pore constrictions and unbending pathways characterize the 3D structure of intervessel pit membranes in angiosperm xylem
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-13
    Ya Zhang, Cora Carmesin, Lucian Kaack, Matthias M. Klepsch, Martyna Kotowska, Tabea Matei, H. Jochen Schenk, Matthias Weber, Paul Walther, Volker Schmidt, Steven Jansen

    Pit membranes between xylem vessels play a major role in angiosperm water transport. Yet, their three‐dimensional (3D) structure as fibrous porous media remains unknown, largely due to technical challenges and sample preparation artefacts. Here, we applied a modelling approach based on thickness measurements of fresh and fully shrunken pit membranes of seven species. Pore constrictions were also investigated visually by perfusing fresh material with colloidal gold particles of known sizes. Based on a shrinkage model, fresh pit membranes showed tiny pore constrictions of ca. 20 nm, but a very high porosity (i.e. pore volume fraction) of on average 0.81. Perfusion experiments showed similar pore constrictions in fresh samples, well below 50 nm based on transmission electron microscopy. Drying caused a 50% shrinkage of pit membranes, resulting in much smaller pore constrictions. These findings suggest that pit membranes represent a mesoporous medium, with the pore space characterized by multiple constrictions. Constrictions are much smaller than previously assumed, but the pore volume is large and highly interconnected. Pores do not form highly tortuous, bent, or zigzagging pathways. These insights provide a novel view on pit membranes, which is essential to develop a mechanistic, 3D understanding of air‐seeding through this porous medium.

    更新日期:2019-11-13
  • Beyond rest and quiescence (endodormancy and ecodormancy): A novel model for quantifying plant–environment interaction in bud dormancy release
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-13
    Robin Lundell, Heikki Hänninen, Timo Saarinen, Helena Åström, Rui Zhang

    Bud dormancy of plants has traditionally been explained either by physiological growth arresting conditions in the bud or by unfavourable environmental conditions, such as non‐growth‐promoting low air temperatures. This conceptual dichotomy has provided the framework also for developing process‐based plant phenology models. Here, we propose a novel model that in addition to covering the classical dichotomy as a special case also allows the quantification of an interaction of physiological and environmental factors. According to this plant–environment interaction suggested conceptually decades ago, rather than being unambiguous, the concept of “non‐growth‐promoting low air temperature” depends on the dormancy status of the plant. We parameterized the model with experimental results of growth onset for seven boreal plant species and found that based on the strength of the interaction, the species can be classified into three dormancy types, only one of which represents the traditional dichotomy. We also tested the model with four species in an independent experiment. Our study suggests that interaction of environmental and physiological factors may be involved in many such phenomena that have until now been considered simply as plant traits without any considerations of effects of the environmental factors.

    更新日期:2019-11-13
  • Inhibition of DNA demethylation enhances plant tolerance to cadmium toxicity by improving iron nutrition
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-12
    Shi Kai Fan, Jia Yuan Ye, Lin Lin Zhang, Hong Shan Chen, Hai Hua Zhang, Ya Xin Zhu, Xing Xing Liu, Chong Wei Jin

    Although the alteration of DNA methylation due to abiotic stresses, such as exposure to the toxic metal cadmium (Cd), has been often observed in plants, little is known about whether such epigenetic changes are linked to the ability of plants to adapt to stress. Herein, we report a close linkage between DNA methylation and the adaptational responses in Arabidopsis plants under Cd stress. Exposure to Cd significantly inhibited the expression of three DNA demethylase genes ROS1/DML2/DML3 (RDD) and elevated DNA methylation at the genome‐wide level in Col‐0 roots. Furthermore, the profile of DNA methylation in Cd‐exposed Col‐0 roots was similar to that in the roots of rdd triple mutants, which lack RDD, indicating that Cd‐induced DNA methylation is associated with the inhibition of RDD. Interestingly, the elevation in DNA methylation in rdd conferred a higher tolerance against Cd stress and improved cellular Fe nutrition in the root tissues. In addition, lowering the Fe supply abolished improved Cd tolerance due to the lack of RDD in rdd. Together, these data suggest that the inhibition of RDD‐mediated DNA demethylation in the roots by Cd would in turn enhance plant tolerance to Cd stress by improving Fe nutrition through a feedback mechanism.

    更新日期:2019-11-13
  • Epigenetic signatures of stress adaptation and flowering regulation in response to extended drought and recovery in Zea mays
    Plant Cell Environ. (IF 5.624) Pub Date : 2019-11-12
    Cristian Forestan, Silvia Farinati, Federico Zambelli, Giulio Pavesi, Vincenzo Rossi, Serena Varotto

    During their lifespan, plants respond to a multitude of stressful factors. Dynamic changes in chromatin and concomitant transcriptional variations control stress response and adaptation, with epigenetic memory mechanisms integrating environmental conditions and appropriate developmental programs over the time. Here we analyzed transcriptome and genome‐wide histone modifications of maize plants subjected to a mild and prolonged drought stress just before the flowering transition. Stress was followed by a complete recovery period to evaluate drought memory mechanisms. Three categories of stress‐memory genes were identified: i) “transcriptional memory” genes, with stable transcriptional changes persisting after the recovery; ii) “epigenetic memory candidate” genes in which stress‐induced chromatin changes persist longer than the stimulus, in absence of transcriptional changes; iii) “delayed memory” genes, not immediately affected by the stress, but perceiving and storing stress signal for a delayed response. This last memory mechanism is described for the first time in drought response. In addition, applied drought stress altered floral patterning, possibly by affecting expression and chromatin of flowering regulatory genes. Altogether, we provided a genome‐wide map of the coordination between genes and chromatin marks utilized by plants to adapt to a stressful environment, describing how this serves as a backbone for setting stress memory.

    更新日期:2019-11-13
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
加州大学洛杉矶分校
上海纽约大学William Glover
南开大学化学院周其林
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug