当前期刊: "植物"类期刊
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • FaMYB9 is involved in the regulation of C6 volatile biosynthesis in strawberry
    Plant Sci. (IF 3.785) Pub Date : 2020-01-24
    Hongyan Lu; Zisheng Luo; Lei Wang; Wusheng Liu; Dong Li; Tarun Belwal; Yanqun Xu; Li Li

    The large-scale untargeted proteomic and metabolomic studies were conducted in strawberry (Fragaria × ananassa) cv. Akihime fruit at five developmental stages. We found that some C6 volatiles highly contributed to the enrichment of volatiles at the red stage of strawberry fruit. We found that 12 genes involved in LOX pathway for volatile biosynthesis showed multiple patterns in protein abundance during fruit development and ripening, and 9 out of the 12 genes exhibited a significant increase in their relative expression levels at the red stage of fruit. We also found that the MYB9 gene (FaMYB9) expression level was positively correlated with the content of C6 volatiles (R = 0.989) and with the relative expression level and protein abundance of FaLOX5 at different strawberry fruit developmental stages (R = 0.954). The interaction between FaMYB9 and FaLOX5 was detected by yeast two-hybrid, co-immunoprecipitation (Co-IP), bimolecular fluorescence complementation (BiFC), and immunofluorescence (IF) analyses. Transient silencing of FaMYB9 delayed the fruit development and ripening, resulting in a significant decrease in the contents of C6 volatiles, while overexpression of FaMYB9 increased the fruit development and ripening and the contents of C6 volatiles in Akihime fruit. Therefore, FaMYB9 is positively involved in C6 volatile biosynthesis.

    更新日期:2020-01-24
  • GmGPA3 is involved in post-Golgi trafficking of storage proteins and cell growth in soybean cotyledons
    Plant Sci. (IF 3.785) Pub Date : 2020-01-24
    Zhongyan Wei; Yu Chen; Bo Zhang; Yulong Ren; Lijuan Qiu

    As the major nutritional component in soybean seeds storage proteins are initially synthesized on the endoplasmic reticulum as precursors and subsequently delivered to protein storage vacuoles (PSVs) via the Golgi-mediated pathway where they are converted into mature subunits and accumulated. However, the molecular machinery required for storage protein trafficking in soybean remains largely unknown. In this study, we cloned the sole soybean homolog of OsGPA3 that encodes a plant-unique kelch-repeat regulator of post-Golgi vesicular traffic for rice storage protein sorting. A complementation test showed that GmGPA3 could rescue the rice gpa3 mutant. Biochemical assays verified that GmGPA3 physically interacts with GmRab5 and its guanine exchange factor (GEF) GmVPS9. Expression of GmGPA3 had no obvious effect on the GEF activity of GmVPS9 toward GmRab5a. Notably, knock-down of GmGPA3 disrupted the trafficking of mmRFP-CT10 (an artificial cargo destined for PSVs) in developing soybean cotyledons. We identified two putative GmGPA3 interacting partners (GmGMG3 and GmGMG11) by screening a yeast cDNA library. Overexpression of GmGPA3 or GmGMG3 caused shrunken cotyledon cells. Our overall results suggested that GmGPA3 plays an important role in cell growth and development, in addition to its conserved role in mediating storage protein trafficking in soybean cotyledons.

    更新日期:2020-01-24
  • Novel insights into expansion and functional diversification of MIR169 family in tomato
    Planta (IF 3.060) Pub Date : 2020-01-24
    Sombir Rao, Sonia Balyan, Sarita Jha, Saloni Mathur

    Abstract Main conclusion Expansion of MIR169 members by duplication and new mature forms, acquisition of new promoters, differential precursor-miRNA processivity and engaging novel targets increase the functional diversification of MIR169 in tomato. Abstract MIR169 family is an evolutionarily conserved miRNA family in plants. A systematic in-depth analysis of MIR169 family in tomato is lacking. We report 18 miR169 precursors, annotating new loci for MIR169a, b and d, as well as 3 novel mature isoforms (MIR169f/g/h). The family has expanded by both tandem- and segmental-duplication events during evolution. A tandem-pair MIR169b/b-1 and MIR169b-2/h is polycistronic in nature coding for three MIR169b isoforms and a new variant miR169h, that is evidently absent in the wild relatives S. pennellii and S. pimpinellifolium. Seven novel miR169 targets including RNA-binding protein, protein-phosphatase, aminotransferase, chaperone, tetratricopeptide-repeat-protein, and transcription factors ARF-9B and SEPELLATA-3 were established by efficient target cleavage in the presence of specific precursors as well as increased target abundance upon miR169 chelation by short-tandem-target-mimic construct in transient assays. Comparative antagonistic expression profiles of MIR169:target pairs suggest MIR169 family as ubiquitous regulator of various abiotic stresses (heat, cold, dehydration and salt) and developmental pathways. This regulation is partly brought about by acquisition of new promoters as demonstrated by promoter MIR169:GUS reporter assays as well as differential processivity of different precursors and miRNA cleavage efficiencies. Thus, the current study augments the functional horizon of MIR169 family with applications for stress tolerance in crops.

    更新日期:2020-01-24
  • Antibacterial, antitubercular, antimalarial and cytotoxic substances from the endophytic Streptomyces sp. TBRC7642
    Phytochemistry (IF 2.905) Pub Date : 2020-01-24
    Nantiya Bunbamrung; Chakapong Intaraudom; Aibrohim Dramae; Chitti Thawai; Sarin Tadtong; Patchanee Auncharoen; Pattama Pittayakhajonwut
    更新日期:2020-01-24
  • Fast photosynthesis measurements for phenotyping photosynthetic capacity of rice
    Plant Methods (IF 3.170) Pub Date : 2020-01-24
    Tingting Du; Ping Meng; Jianliang Huang; Shaobing Peng; Dongliang Xiong

    Over the past decades, the structural and functional genomics of rice have been deeply studied, and high density of molecular genetic markers have been developed. However, the genetic variation in leaf photosynthesis, the most important trait for rice yield improvement, was rarely studied. The lack of photosynthesis phenotyping tools is one of the bottlenecks, as traditional direct photosynthesis measurements are very low-throughput, and recently developed high-throughput methods are indirect measurements. Hence, there is an urgent need for a fast, accurate and direct measurement approach. We reported a fast photosynthesis measurement (FPM) method for phenotyping photosynthetic capacity of rice, which measures photosynthesis of excised tillers in environment-controlled lab conditions. The light response curves measured using FPM approach coped well with that the curves measured using traditional gas exchange approach. Importantly, the FPM technique achieved an average throughput of 5.4 light response curves per hour, which was 3 times faster than the 1.8 light response curves per hour using the traditional method. Tillers sampled at early morning had the highest photosynthesis, stomatal conductance and the lowest variability. In addition, even 12 h after sampling, there was no significant difference of photosynthesis rate between excised tillers and in situ. We finally investigated the genetic variations of photosynthetic traits across 568 F2 lines using the FPM technique and discussed the logistics of screening several hundred samples per day per instrumental unit using FPM to generate a wealth of photosynthetic phenotypic data, which might help to improve the selection power in large populations of rice with the ultimate aim of improving yield through improved photosynthesis. Here we developed a high-throughput method that can measure the rice leaf photosynthetic capacity approximately 10 times faster than traditional gas exchange approaches. Importantly, this method can overcome measurement errors caused by environmental heterogeneity under field conditions, and it is possible to measure 12 or more hours per day under lab conditions.

    更新日期:2020-01-24
  • Correction to: Linear relation between leaf xylem water potential and transpiration in pearl millet during soil drying
    Plant Soil (IF 3.259) Pub Date : 2020-01-24
    Gaochao Cai, Mutez Ali Ahmed, Michaela A. Dippold, Mohsen Zarebanadkouki, Andrea Carminati

    In the original version of this article, equations 4 and 9 unfortunately contained errors

    更新日期:2020-01-24
  • Guard cells integrate light and temperature signals to control stomatal aperture
    Plant Physiol. (IF 6.305) Pub Date : 2020-01-23
    Kalliopi-Ioanna Kostaki, Aude Coupel-Ledru, Verity C Bonnell, Mathilda Gustavsson, Peng Sun, Fiona J Mclaughlin, Donald P Fraser, Deirdre H McLachlan, Alistair M. Hetherington, Antony N Dodd, Keara A. Franklin

    High temperature promotes guard cell expansion, which opens stomatal pores to facilitate leaf cooling. How the high temperature signal is perceived and transmitted to regulate stomatal aperture is, however, unknown. Here, we used a reverse-genetics approach to understand high temperature-mediated stomatal opening in Arabidopsis thaliana. Our findings reveal that high temperature-induced guard cell movement requires components involved in blue light-mediated stomatal opening, suggesting crosstalk between light and temperature signalling pathways. The molecular players involved include phototropin photoreceptors, plasma membrane H+-ATPases, and multiple members of the 14-3-3 protein family. We further show that phototropin-deficient mutants display impaired rosette evapotranspiration and leaf cooling at high temperatures. Blocking the interaction of 14-3-3 proteins with their client proteins severely impairs high temperature-induced stomatal opening, but has no effect on the induction of heat-sensitive guard cell transcripts, supporting the existence of an additional intracellular high-temperature response pathway in plants.

    更新日期:2020-01-24
  • A cytosol-localized geranyl diphosphate synthase from Lithospermum erythrorhizon and its molecular evolution
    Plant Physiol. (IF 6.305) Pub Date : 2020-01-23
    Hayato Ueoka, Kanako Sasaki, Tatsuya Miyawaki, Takuji Ichino, Kanade Tatsumi, Shiro Suzuki, Hirobumi Yamamoto, Nozomu Sakurai, Hideyuki Suzuki, Daisuke Shibata, Kazufumi Yazaki

    Geranyl diphosphate (GPP) is the direct precursor of all monoterpenoids and is the prenyl source of many meroterpenoids, such as geranylated coumarins. GPP synthase (GPPS) localized in plastids is responsible for providing the substrate for monoterpene synthases and prenyltransferases for synthesis of aromatic substances that are also present in plastids, but GPPS activity in Lithospermum erythrorhizon localizes to the cytosol, in which GPP is utilized for the biosynthesis of naphthoquinone pigments, which are shikonin derivatives. This study describes the identification of the cytosol-localized GPPS gene, LeGPPS, through expressed sequence tag (EST)- and homology-based approaches followed by functional analyses. The deduced amino acid sequence of the unique LeGPPS showed greater similarity to that of farnesyl diphosphate synthase (FPPS), which generally localizes to the cytosol, than to plastid-localized conventional GPPS. Biochemical characterization revealed that recombinant LeGPPS predominantly produces GPP along with a trace amount of FPP. LeGPPS expression was mainly detected in root bark, in which shikonin derivatives are produced, and in shikonin-producing cultured cells. The GFP fusion protein in onion (Allium cepa) cells localized to the cytosol. Site-directed mutagenesis of LeGPPS and another FPPS homolog identified in this study, LeFPPS1, showed that the His residue at position 100 of LeGPPS, adjacent to the first aspartate rich motif, contributes to substrate preference and product specificity, leading to GPP formation. These results suggest that LeGPPS, which is involved in shikonin biosynthesis, is recruited from cytosolic FPPS and that point mutation(s) result in the acquisition of GPPS activity.

    更新日期:2020-01-24
  • HvAKT2 and HvHAK1 confer drought tolerance in barley through enhanced leaf mesophyll H+ homoeostasis
    Plant Biotech. J. (IF 6.840) Pub Date : 2020-01-24
    Xue Feng; Wenxing Liu; Cheng‐Wei Qiu; Fanrong Zeng; Yizhou Wang; Guoping Zhang; Zhong‐Hua Chen; Feibo Wu

    Plant K+ uptake typically consists low—affinity mechanisms mediated by Shaker K+ channels (AKT/KAT/KC) and high‐affinity mechanisms regulated by HAK/KUP/KT transporters, which are extensively studied. However, the evolutionary and genetic roles of both K+ uptake mechanisms for drought tolerance are not fully explored in crops adapted to dryland agriculture. Here, we employed evolutionary bioinformatics, biotechnological and electrophysiological approaches to determine the role of two important K+ transporters HvAKT2 and HvHAK1 in drought tolerance in barley. HvAKT2 and HvHAK1 were cloned and functionally characterized using barley stripe mosaic virus‐induced gene silencing (BSMV‐VIGS) in drought‐tolerant wild barley XZ5 and agrobacterium‐mediated gene transfer in the barley cultivar Golden Promise. The hallmarks of the K+ selective filters of AKT2 and HAK1 are both found in homologues from strepotophyte algae, and they are evolutionarily conserved in strepotophyte algae and land plants. HvAKT2 and HvHAK1 are both localized to the plasma membrane and have high selectivity to K+ and Rb+ over other tested cations. Overexpression of HvAKT2 and HvHAK1 enhanced K+ uptake and H+ homoeostasis leading to drought tolerance in these transgenic lines. Moreover, HvAKT2‐ and HvHAK1‐overexpressing lines showed distinct response of K+, H+ and Ca2+ fluxes across plasma membrane and production of nitric oxide and hydrogen peroxide in leaves as compared to the wild type and silenced lines. High‐ and low‐affinity K+ uptake mechanisms and their coordination with H+ homoeostasis play essential roles in drought adaptation of wild barley. These findings can potentially facilitate future breeding programs for resilient cereal crops in a changing global climate.

    更新日期:2020-01-24
  • The major‐effect quantitative trait locus Fnl7.1 encodes a late embryogenesis abundant protein associated with fruit neck length in cucumber
    Plant Biotech. J. (IF 6.840) Pub Date : 2020-01-24
    Xuewen Xu; Chenxi Wei; Qianya Liu; Wenqing Qu; Xiaohua Qi; Qiang Xu; Xuehao Chen

    Fruit neck length (FNL) is an important quality trait in cucumber because it directly affects its market value. However, its genetic basis remains largely unknown. We identified a candidate gene for FNL in cucumber using a next‐generation sequencing‐based bulked segregant analysis in F2 populations, derived from a cross between Jin5‐508 (long necked) and YN (short necked). A quantitative trait locus (QTL) on chromosome 7, Fnl7.1, was identified through a genome‐wide comparison of single nucleotide polymorphisms between long and short FNL F2 pools, and it was confirmed by traditional QTL mapping in multiple environments. Fine genetic mapping, sequences alignment and gene expression analysis revealed that CsFnl7.1 was the most likely candidate Fnl7.1 locus, which encodes a late embryogenesis abundant protein. The increased expression of CsFnl7.1 in long‐necked Jin5‐508 may be attributed to mutations in the promoter region upstream of the gene body. The function of CsFnl7.1 in FNL control was confirmed by its overexpression in transgenic cucumbers. CsFnl7.1 regulates fruit neck development by modulating cell expansion. Probably, this is achieved through the direct protein–protein interactions between CsFnl7.1 and a dynamin‐related protein CsDRP6 and a germin‐like protein CsGLP1. Geographical distribution differences of the FNL phenotype were found among the different cucumber types. The East Asian and Eurasian cucumber accessions were highly enriched with the long‐necked and short‐necked phenotypes, respectively. A further phylogenetic analysis revealed that the Fnl7.1 locus might have originated from India. Thus, these data support that the CsFnl7.1 has an important role in increasing cucumber FNL.

    更新日期:2020-01-24
  • The genome of kenaf (Hibiscus cannabinus L.) provides insights into bast fiber and leaf shape biogenesis
    Plant Biotech. J. (IF 6.840) Pub Date : 2020-01-23
    Liwu Zhang; Yi Xu; Xingtan Zhang; Xiaokai Ma; Lilan Zhang; Zhenyang Liao; Qing Zhang; Xuebei Wan; Yan Cheng; Jisen Zhang; Dongxu Li; Liemei Zhang; Jiantang Xu; Aifen Tao; Lihui Lin; Pingping Fang; Shuai Chen; Rui Qi; Xiuming Xu; Jianmin Qi; Ray Ming

    Kenaf is an ancient crop that is widely cultivated as a source of bast (phloem) fibers, the phytoremediation of heavy metal‐contaminated farmlands, and textile relevant compounds. Leaf shape played a unique role in kenaf improvement, due to the inheritance as a single locus and the association with fiber development in typical lobed‐leaf varieties. Here we report a high‐quality genome assembly and annotation for var. ‘Fuhong 952’ with 1,078 Mbp genome and 66,004 protein‐coding genes integrating single‐molecule real‐time sequencing, a high‐density genetic map, and high‐throughput chromosome conformation capture techniques. Gene mapping assists the identification of a homeobox transcription factor LATE MERISTEM IDENTITY 1 (HcLMI1) gene controlling lobed‐leaf. Virus‐induced gene silencing (VIGS) of HcLMI1 in a lobed‐leaf variety was critical to induce round‐like leaf formation. Candidate genes involved in cell wall formation were found in quantitative trait loci (QTL) for fiber yield and quality related traits. Comparative genomic and transcriptome analyses revealed key genes involved in bast fiber formation, among which there are twice as many cellulose synthase A (CesA) genes due to a recent whole‐genome duplication after divergence from Gossypium. Population genomic analysis showed two recent population bottlenecks in kenaf, suggesting domestication and improvement process have led to an increase in fiber biogenesis and yield. This chromosome‐scale genome provides an important framework and toolkit for sequence‐directed genetic improvement of fiber crops.

    更新日期:2020-01-24
  • Photosynthesis and photosynthetic efficiencies along the terrestrial plant’s phylogeny: lessons for improving crop photosynthesis
    Plant J. (IF 5.726) Pub Date : 2020-01-24
    Jaume Flexas; Marc Carriquí

    Photosynthesis is the basis of all life on Earth. Surprisingly, until very recently, data on photosynthesis, photosynthetic efficiencies, and photosynthesis limitations in terrestrial land plants other than spermatophytes were very scarce. Here we provide an updated data compilation showing that maximum photosynthesis rates (expressed either on an area or dry mass basis) progressively scale along the land plant’s phylogeny, from lowest values in bryophytes to largest in angiosperms. Unexpectedly, both photosynthetic water (WUE) and nitrogen (PNUE) use efficiencies also scale positively through the phylogeny, for which it has been commonly reported that these two efficiencies tend to trade‐off between them when comparing different genotypes or a single species subject to different environmental conditions. After providing experimental evidence that these observed trends are mostly due to an increased mesophyll conductance to CO2 – associated with specific anatomical changes – along the phylogeny, we discuss how these findings on a large phylogenetic scale can provide useful information to address potential photosynthetic improvements in crops in the near future.

    更新日期:2020-01-24
  • The Ficus erecta genome towards Ceratocystis canker resistance breeding in common fig (F. carica)
    Plant J. (IF 5.726) Pub Date : 2020-01-24
    Kenta Shirasawa; Hiroshi Yakushiji; Ryotaro Nishimura; Takeshige Morita; Shota Jikumaru; Hidetoshi Ikegami; Atsushi Toyoda; Hideki Hirakawa; Sachiko Isobe

    Ficus erecta, a wild relative of common fig (F. carica), is a donor of Ceratocystis canker resistance in fig breeding programs. Interspecific hybridization followed by recurrent backcrossing is an effective method to transfer the resistance trait from wild to cultivated fig; however, this is time consuming and labor‐intensive for trees, especially for gynodioecious plants such as fig. In this study, genome resources were developed for F. erecta to facilitate fig breeding programs. The genome sequence of F. erecta was determined using single‐molecule real‐time sequencing technology. The resultant assembly spanned 331.6 Mb with 538 contigs and an N50 length of 1.9 Mb, from which 51,806 high‐confidence genes were predicted. Pseudomolecule sequences corresponding to the chromosomes of F. erecta were established with a genetic map based on single nucleotide polymorphisms from double‐digest restriction‐site associated DNA sequencing. Subsequent linkage analysis and whole genome resequencing identified a candidate gene for the Ceratocystis canker resistance trait. Genome‐wide genotyping analysis enabled selection of female lines that possessed resistance and effective elimination of donor genome from progeny. The genome resources provided in this study will accelerate and enhance disease resistance breeding programs in fig.

    更新日期:2020-01-24
  • An importin‐beta like protein mediates lignin modification induced dwarfism in Arabidopsis
    Plant J. (IF 5.726) Pub Date : 2020-01-23
    Chinmayee Panda; Xin Li; Amanda Wager; Han‐Yi Chen; Xu Li

    Perturbation of lignin biosynthesis often results in severe growth and developmental defects in plants, which imposes practical limitations to genetic enhancement of lignocellulosic biomass for biofuel production. Currently, little is known about the cellular and genetic mechanisms of this important phenomenon. Here we show that defects in both cell division and cell expansion underlie the dwarfism of an Arabidopsis lignin mutant ref8, and report the identification of a GROWTH INHIBITION RELIEVED 1 (GIR1) gene from a suppressor screen. GIR1 encodes an importin‐beta like protein required for the nuclear import of MYB4, a transcriptional repressor of phenylpropanoid metabolism. Disruption of GIR1 and MYB4 similarly alleviates the cellular defects and growth inhibition in ref8, suggesting that the growth rescue effect of gir1 is likely due to compromised MYB4 transport and function. Importantly, the phenylpropanoid perturbation is not alleviated in gir1 ref8 and myb4 ref8, suggesting that the function of MYB4 in growth inhibition of lignin‐modified plants is likely to be distinct from its known role in transcriptional regulation of phenylpropanoid biosynthetic genes. This study also provides evidence that lignin‐modification induced dwarfism is not merely due to compromised water transport brought about by lignin deficiency, as gir1 has no effect on the growth inhibition of other lignin mutants that show the collapsed xylem phenotype.

    更新日期:2020-01-24
  • Endoplasmic reticulum‐mediated unfolded protein response is an integral part of singlet oxygen signaling in plants
    Plant J. (IF 5.726) Pub Date : 2020-01-23
    Inès Beaugelin; Anne Chevalier; Stefano D’Alessandro; Brigitte Ksas; Michel Havaux

    Singlet oxygen (1O2) is a by‐product of photosynthesis which triggers a signaling pathway leading to stress acclimation or to cell death. By analyzing gene expressions in a 1O2‐overproducing Arabidopsis mutant (ch1) under different light regimes, we show here that the 1O2 signaling pathway involves the endoplasmic reticulum (ER)‐mediated unfolded protein response (UPR). ch1 plants in low light exhibited a moderate activation of UPR genes, in particular bZIP60, and low concentrations of the UPR‐inducer tunicamycin enhanced tolerance to photooxidative stress, together suggesting a role for UPR in plant acclimation to low 1O2 levels. Exposure of ch1 to high light stress ultimately leading to cell death resulted in a marked upregulation of the two UPR branches (bZIP60/IRE1 and bZIP28/bZIP17). Accordingly, mutational suppression of bZIP60 and bZIP28 increased plant phototolerance, and a strong UPR activation by high tunicamycin concentrations promoted high‐light‐induced cell death. Conversely, light acclimation of ch1 to 1O2 stress put a limitation in the high light‐induced expression of UPR genes, except for the gene encoding the BIP3 chaperone which was selectively up‐regulated. BIP3 deletion enhanced Arabidopsis photosensitivity while plants treated with a chemical chaperone exhibited enhanced phototolerance. In conclusion, 1O2 induces the ER‐mediated UPR response that fulfills a dual role in high light stress: a moderate UPR, with selective induction of BIP3, is part of the acclimatory response to 1O2, and a strong activation of the whole UPR is associated with cell death.

    更新日期:2020-01-24
  • 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
  • Isolation and structure elucidation of siliendines A‒D, new β-carboline alkaloids from Silene seoulensis
    Phytochem. Lett. (IF 1.338) Pub Date : 2020-01-23
    Changon Seo; Hyoung Seok Shin; Ji Eun Lee; Yeon Woo Jung; Jin Kyu Kim; Jin Gwan Kwon; Wonsik Jeong; Chun Whan Choi; Joa Sub Oh; Seong Su Hong
    更新日期:2020-01-24
  • Diurnal.plant.tools: Comparative Transcriptomic and Co-expression Analyses of Diurnal Gene Expression of the Archaeplastida Kingdom
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-10
    Ng J, Tan Q, Ferrari C, et al.

    Almost all organisms coordinate some aspects of their biology through the diurnal cycle. Photosynthetic organisms, and plants especially, have established complex programs that coordinate physiological, metabolic and developmental processes with the changing light. The diurnal regulation of the underlying transcriptional processes is observed when groups of functionally related genes (gene modules) are expressed at a specific time of the day. However, studying the diurnal regulation of these gene modules in the plant kingdom was hampered by the large amount of data required for the analyses. To meet this need, we used gene expression data from 17 diurnal studies spanning the whole Archaeplastida kingdom (Plantae kingdom in the broad sense) to make an online diurnal database. We have equipped the database with tools that allow user-friendly cross-species comparisons of gene expression profiles, entire co-expression networks, co-expressed clusters (involved in specific biological processes), time-specific gene expression and others. We exemplify how these tools can be used by studying three important biological questions: (i) the evolution of cell division, (ii) the diurnal control of gene modules in algae and (iii) the conservation of diurnally controlled modules across species. The database is freely available at http://diurnal.plant.tools.

    更新日期:2020-01-24
  • Fertilization-Coupled Sperm Nuclear Fusion Is Required for Normal Endosperm Nuclear Proliferation
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-08-14
    Maruyama D, Higashiyama T, Endo T, et al.

    Angiosperms exhibit double fertilization, a process in which one of the sperm cells released from the pollen tube fertilizes the egg, while the other sperm cell fertilizes the central cell, giving rise to the embryo and endosperm, respectively. We have previously reported two polar nuclear fusion-defective double knockout mutants of Arabidopsis thaliana immunoglobulin binding protein (BiP), a molecular chaperone of the heat shock protein 70 (Hsp70) localized in the endoplasmic reticulum (ER), (bip1 bip2) and its partner ER-resident J-proteins, ERdj3A and P58IPK (erdj3a p58ipk). These mutants are defective in the fusion of outer nuclear membrane and exhibit characteristic seed developmental defects after fertilization with wild-type pollen, which are accompanied by aberrant endosperm nuclear proliferation. In this study, we used time-lapse live-cell imaging analysis to determine the cause of aberrant endosperm nuclear division in these mutant seeds. We found that the central cell of bip1 bip2 or erdj3a p58ipk double mutant female gametophytes was also defective in sperm nuclear fusion at fertilization. Sperm nuclear fusion was achieved after the onset of the first endosperm nuclear division. However, division of the condensed sperm nucleus resulted in aberrant endosperm nuclear divisions and delayed expression of paternally derived genes. By contrast, the other double knockout mutant, erdj3b p58ipk, which is defective in the fusion of inner membrane of polar nuclei but does not show aberrant endosperm nuclear proliferation, was not defective in sperm nuclear fusion at fertilization. We thus propose that premitotic sperm nuclear fusion in the central cell is critical for normal endosperm nuclear proliferation.

    更新日期:2020-01-24
  • Different Plant Species Have Common Sequence Features Related to mRNA Degradation Intermediates
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-10
    Ueno D, Mukuta T, Yamasaki S, et al.

    mRNA degradation is an important cellular mechanism involved in the control of gene expression. Several genome-wide profiling methods have been developed for detecting mRNA degradation in plants and animals. However, because many of these techniques use poly (A) mRNA for library preparation, degradation intermediates are often only detected near the 3′-ends of transcripts. Previously, we developed the Truncated RNA End Sequencing (TREseq) method using Arabidopsis thaliana, and demonstrated that this method ameliorates 3′-end bias. In analyses using TREseq, we observed G-rich sequences near the 5′-ends of degradation intermediates. However, this finding remained to be confirmed in other plant species. Hence, in this study, we conducted TREseq analyses in Lactuca sativa (lettuce), Oryza sativa (rice) and Rosa hybrida (rose). These species including A. thaliana were selected to encompass a diverse range in the angiosperm phylogeny. The results revealed similar sequence features near the 5′-ends of degradation intermediates, and involvement of translation process in all four species. In addition, homologous genes have similar efficiencies of mRNA degradation in different plants, suggesting that similar mechanisms of mRNA degradation are conserved across plant species. These strong sequence features were not observed in previous degradome analyses among different species in plants.

    更新日期:2020-01-24
  • Cytosolic Acetyl-CoA Generated by ATP-Citrate Lyase Is Essential for Acetylation of Cell Wall Polysaccharides
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-10
    Zhong R, Cui D, Richardson E, et al.

    Plant cell wall polysaccharides, including xylan, glucomannan, xyloglucan and pectin, are often acetylated. Although a number of acetyltransferases responsible for the acetylation of some of these polysaccharides have been biochemically characterized, little is known about the source of acetyl donors and how acetyl donors are translocated into the Golgi, where these polysaccharides are synthesized. In this report, we investigated roles of ATP-citrate lyase (ACL) that generates cytosolic acetyl-CoA in cell wall polysaccharide acetylation and effects of simultaneous mutations of four Reduced Wall Acetylation (RWA) genes on acetyl-CoA transport into the Golgi in Arabidopsis thaliana. Expression analyses of genes involved in the generation of acetyl-CoA in different subcellular compartments showed that the expression of several ACL genes responsible for cytosolic acetyl-CoA synthesis was elevated in interfascicular fiber cells and induced by secondary wall-associated transcriptional activators. Simultaneous downregulation of the expression of ACL genes was demonstrated to result in a substantial decrease in the degree of xylan acetylation and a severe alteration in secondary wall structure in xylem vessels. In addition, the degree of acetylation of other cell wall polysaccharides, including glucomannan, xyloglucan and pectin, was also reduced. Moreover, Golgi-enriched membrane vesicles isolated from the rwa1/2/3/4 quadruple mutant were found to exhibit a drastic reduction in acetyl-CoA transport activity compared with the wild type. These findings indicate that cytosolic acetyl-CoA generated by ACL is essential for cell wall polysaccharide acetylation and RWAs are required for its transport from the cytosol into the Golgi.

    更新日期:2020-01-24
  • Photosynthesis Regulation in Response to Fluctuating Light in the Secondary Endosymbiont Alga Nannochloropsis gaditana
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-12
    Bellan A, Bucci F, Perin G, et al.

    In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging because they drive oversaturation of photosynthesis with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (non-photochemical quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution, and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. Nannochloropsis gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of the ineffective regulation of electron transport in this species. The role of NPQ, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

    更新日期:2020-01-24
  • Altered Plant and Nodule Development and Protein S-Nitrosylation in Lotus japonicus Mutants Deficient in S-Nitrosoglutathione Reductases
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-16
    Matamoros M, Cutrona M, Wienkoop S, et al.

    Nitric oxide (NO) is a crucial signaling molecule that conveys its bioactivity mainly through protein S-nitrosylation. This is a reversible post-translational modification (PTM) that may affect protein function. S-nitrosoglutathione (GSNO) is a cellular NO reservoir and NO donor in protein S-nitrosylation. The enzyme S-nitrosoglutathione reductase (GSNOR) degrades GSNO, thereby regulating indirectly signaling cascades associated with this PTM. Here, the two GSNORs of the legume Lotus japonicus, LjGSNOR1 and LjGSNOR2, have been functionally characterized. The LjGSNOR1 gene is very active in leaves and roots, whereas LjGSNOR2 is highly expressed in nodules. The enzyme activities are regulated in vitro by redox-based PTMs. Reducing conditions and hydrogen sulfide-mediated cysteine persulfidation induced both activities, whereas cysteine oxidation or glutathionylation inhibited them. Ljgsnor1 knockout mutants contained higher levels of S-nitrosothiols. Affinity chromatography and subsequent shotgun proteomics allowed us to identify 19 proteins that are differentially S-nitrosylated in the mutant and the wild-type. These include proteins involved in biotic stress, protein degradation, antioxidant protection and photosynthesis. We propose that, in the mutant plants, deregulated protein S-nitrosylation contributes to developmental alterations, such as growth inhibition, impaired nodulation and delayed flowering and fruiting. Our results highlight the importance of GSNOR function in legume biology.

    更新日期:2020-01-24
  • Poaceae Type II Galactinol Synthase 2 from Antarctic Flowering Plant Deschampsia antarctica and Rice Improves Cold and Drought Tolerance by Accumulation of Raffinose Family Oligosaccharides in Transgenic Rice Plants
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-12
    Cui L, Byun M, Oh H, et al.

    Deschampsia antarctica is a Poaceae grass that has adapted to and colonized Antarctica. When D. antarctica plants were subjected to cold and dehydration stress both in the Antarctic field and in laboratory experiments, galactinol, a precursor of raffinose family oligosaccharides (RFOs) and raffinose were highly accumulated, which was accompanied by upregulation of galactinol synthase (GolS). The Poaceae monocots have a small family of GolS genes, which are divided into two distinct groups called types I and II. Type II GolSs are highly expanded in cold-adapted monocot plants. Transgenic rice plants, in which type II D. antarctica GolS2 (DaGolS2) and rice GolS2 (OsGolS2) were constitutively expressed, were markedly tolerant to cold and drought stress as compared to the wild-type rice plants. The RFO contents and GolS enzyme activities were higher in the DaGolS2- and OsGolS2-overexpressing progeny than in the wild-type plants under both normal and stress conditions. DaGolS2 and OsGolS2 overexpressors contained reduced levels of reactive oxygen species (ROS) relative to the wild-type plants after cold and drought treatments. Overall, these results suggest that Poaceae type II GolS2s play a conserved role in D. antarctica and rice in response to drought and cold stress by inducing the accumulation of RFO and decreasing ROS levels.

    更新日期:2020-01-24
  • LeGOO: An Expertized Knowledge Database for the Model Legume Medicago truncatula
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-17
    Carrère S, Verdenaud M, Gough C, et al.

    Medicago truncatula was proposed, about three decades ago, as a model legume to study the Rhizobium-legume symbiosis. It has now been adopted to study a wide range of biological questions, including various developmental processes (in particular root, symbiotic nodule and seed development), symbiotic (nitrogen-fixing and arbuscular mycorrhizal endosymbioses) and pathogenic interactions, as well as responses to abiotic stress. With a number of tools and resources set up in M. truncatula for omics, genetics and reverse genetics approaches, massive amounts of data have been produced, as well as four genome sequence releases. Many of these data were generated with heterogeneous tools, notably for transcriptomics studies, and are consequently difficult to integrate. This issue is addressed by the LeGOO (for Legume Graph-Oriented Organizer) knowledge base (https://www.legoo.org), which finds the correspondence between the multiple identifiers of the same gene. Furthermore, an important goal of LeGOO is to collect and represent biological information from peer-reviewed publications, whatever the technical approaches used to obtain this information. The information is modeled in a graph-oriented database, which enables flexible representation, with currently over 200,000 relations retrieved from 298 publications. LeGOO also provides the user with mining tools, including links to the Mt5.0 genome browser and associated information (on gene functional annotation, expression, methylome, natural diversity and available insertion mutants), as well as tools to navigate through different model species. LeGOO is, therefore, an innovative database that will be useful to the Medicago and legume community to better exploit the wealth of data produced on this model species.

    更新日期:2020-01-24
  • Functional Characterization of Three Novel Genes Encoding Diacylglycerol Acyltransferase (DGAT) from Oil-Rich Tubers of Cyperus esculentus
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-18
    Liu D, Ji H, Yang Z.

    Cyperus esculentus is probably the only plant that is known to accumulate large amounts of oil in its tubers. However, the underlying metabolic mechanism and regulatory factors involved in oil synthesis of tubers are still largely unclear. In this study, one gene encoding type I diacylglycerol acyltransferase (DGAT) (CeDGAT1) and two genes encoding type II DGAT (CeDGAT2a and CeDGAT2b) from C. esculentus were identified and functionally analyzed. All three DGAT genes were found to be expressed in tuber, root and leaf tissues. CeDGAT1 is highly expressed in roots and leaves, whereas CeDGAT2b is dominantly expressed in tubers. Furthermore, the temporal expression pattern of CeDGAT2b is well coordinated with the oil accumulation in developing tubers. When each CeDGAT was heterologously expressed in triacylglycerol (TAG)-deficient mutant of Saccharomyces cerevisiae, Arabidopsis thaliana wild type or its TAG1 mutant with AtDGAT1 disruption, only CeDGAT2b showed the ability to restore TAG biosynthesis with lipid body formation in yeast mutant, enhance seed oil production of Arabidopsis wild type and rescue multiple seed phenotypes of TAG1 mutant. In addition, CeDGAT2b was shown to have a substrate preference for unsaturated fatty acids toward TAG synthesis. Taken together, our results indicated that CeDGAT2b from C. esculentus is an actively functional protein and is most likely the major contributor to tuber oil biosynthesis containing common fatty acids, in contrast to oil-rich seeds and fruits where DGAT1 plays a more central role than DGAT2 in oil production accumulating normal fatty acids, whereas DGAT2 is a primary regulator for oil synthesis rich in unusual fatty acids.

    更新日期:2020-01-24
  • An Apple B-Box Protein MdBBX37 Modulates Anthocyanin Biosynthesis and Hypocotyl Elongation Synergistically with MdMYBs and MdHY5
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-24
    An J, Wang X, Espley R, et al.

    As an important environment factor, light affects plant growth and development throughout life. B-BOX (BBX) proteins play key roles in the regulation of light signaling. Although the multiple roles of BBX proteins have been extensively studied in Arabidopsis, the research in apple is much less extensive. In this study, we systematically characterized the negative role of an apple BBX protein MdBBX37 in light signaling, including inhibiting anthocyanin biosynthesis and promoting hypocotyl elongation. We found that MdBBX37 interacted with MdMYB1 and MdMYB9, two key positive regulators of anthocyanin biosynthesis, and inhibited the binding of those two proteins to their target genes and, therefore, negatively regulated anthocyanin biosynthesis. In addition, MdBBX37 directly bound to the promoter of MdHY5, a positive regulator of light signaling, and suppressed its expression, and thus relieved MdHY5-mediated hypocotyl inhibition. Taken together, our investigations suggest that MdBBX37 is a negative regulator of light signaling in apple. Our study will provide reference for further study on the functions of BBX proteins in apple.

    更新日期:2020-01-24
  • Integrated mRNA, MicroRNA Transcriptome and Degradome Analyses Provide Insights into Stamen Development in Moso Bamboo
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-24
    Cheng Z, Hou D, Ge W, et al.

    A flower is an essential organ for sexual reproduction in flowering plants, which has been extensively studied in model plants. In this study, we used transcriptomic, small RNA and degradome analyses to characterize key microRNAs (miRNAs) and their targets in floral organs of moso bamboo. In total, we identified 13,051 differentially expressed genes and 109 known miRNAs from 26 miRNA families. We aligned the miRNAs to known miRNA databases and revealed some conserved as well as novel miRNAs. Sixteen conserved miRNAs were specifically and highly expressed in stamens, including miRNA159 and miRNA166. In situ hybridization shows that miRNA159 plays a key role in the regulation of stamen development, and the expression levels of its targets PheMYB98 and PheMYB42 were low. Furthermore, Phe-MIRNA159 partially recovers phenotypes of mir159ab double mutant. Overexpression of Phe-MIR159 could cause failure in anther dehisce, and the mature pollens could not be dispersed and further reduce fertility in Arabidopsis. Semi-thin section result shows that anther endothelial layer of Phe-MIRNA159 overexpressing lines is lack of secondary thickening, resulting in limited force for anther opening. Phe-miR159 may regulate the expression of genes related to secondary thickening through negative regulation of AtMYB33, affecting the anther dehiscence. Taken together, this study provides insights regarding molecular networks underlying floral organs development of moso bamboo.

    更新日期:2020-01-24
  • RNA Helicases from the DEA(D/H)-Box Family Contribute to Plant NMD Efficiency
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-09-27
    Sulkowska A, Auber A, Sikorski P, et al.

    Nonsense-mediated mRNA decay (NMD) is a conserved eukaryotic RNA surveillance mechanism that degrades aberrant mRNAs comprising a premature translation termination codon. The adenosine triphosphate (ATP)-dependent RNA helicase up-frameshift 1 (UPF1) is a major NMD factor in all studied organisms; however, the complexity of this mechanism has not been fully characterized in plants. To identify plant NMD factors, we analyzed UPF1-interacting proteins using tandem affinity purification coupled to mass spectrometry. Canonical members of the NMD pathway were found along with numerous NMD candidate factors, including conserved DEA(D/H)-box RNA helicase homologs of human DDX3, DDX5 and DDX6, translation initiation factors, ribosomal proteins and transport factors. Our functional studies revealed that depletion of DDX3 helicases enhances the accumulation of NMD target reporter mRNAs but does not result in increased protein levels. In contrast, silencing of DDX6 group leads to decreased accumulation of the NMD substrate. The inhibitory effect of DDX6-like helicases on NMD was confirmed by transient overexpression of RH12 helicase. These results indicate that DDX3 and DDX6 helicases in plants have a direct and opposing contribution to NMD and act as functional NMD factors.

    更新日期:2020-01-24
  • WHIRLY1 Regulates HSP21.5A Expression to Promote Thermotolerance in Tomato
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-10-09
    Zhuang K, Gao Y, Liu Z, et al.

    Heat stress poses a major threat to plant productivity and crop yields. The induction of heat shock proteins (HSPs) by heat shock factors is a principal defense response of plants exposed to heat stress. In this study, we identified and analyzed the heat stress-induced Whirly1 (SlWHY1) gene in tomato (Solanum lycopersicum). We generated various SlWHY1-overexpressing (OE) and SlWHY1-RNA interference (RNAi) lines to investigate the role of WHIRLY1 in thermotolerance. Compared with the wild type (WT), the OE lines showed less wilting, as reflected by their increased membrane stability and soluble sugar content and reduced reactive oxygen species (ROS) accumulation under heat stress. By contrast, RNAi lines with inhibited SlWHY1 expression showed the opposite phenotype and corresponding physiological indices under heat stress. The heat-induced gene SlHSP21.5A, encoding an endoplasmic reticulum-localized HSP, was upregulated in the OE lines and downregulated in the RNAi lines compared with the WT. RNAi-mediated inhibition of SlHSP21.5A expression also resulted in reduced membrane stability and soluble sugar content and increased ROS accumulation under heat stress compared with the WT. SlWHY1 binds to the elicitor response element-like element in the promoter of SlHSP21.5A to activate its transcription. These findings suggest that SlWHY1 promotes thermotolerance in tomato by regulating SlHSP21.5A expression.

    更新日期:2020-01-24
  • Formation of Spherical Palmelloid Colony with Enhanced Lipid Accumulation by Gel Encapsulation of Chlamydomonas debaryana NIES-2212
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-10-07
    Yoshitomi T, Kaminaga S, Sato N, et al.

    Microalgae such as Chlamydomonas reinhardtii accumulate triacylglycerol (TAG), which is a potential source of biofuels, under stress conditions such as nitrogen deprivation, whereas Chlamydomonas debaryana NIES-2212 has previously been identified and characterized as one of the rare species of Chlamydomonas, which massively accumulates TAG in the stationary phase without external stress. As the high density of the cells in the stationary phase was supposed to act as a trigger for the accumulation of TAG in C. debaryana, in this study, C. debaryana was encapsulated in a Ca2+-alginate gel for the culture with high cell density. We discovered that the growth of the encapsulated cells resulted in the formation of spherical palmelloid colonies with high cell density, where daughter cells with truncated flagella remained wrapped within the mother cell walls. Interestingly, gel encapsulation markedly promoted proliferation of C. debaryana cells, and the encapsulated cells reached the stationary phase earlier than that of the free-living cells. Gel encapsulation also enhanced TAG accumulation. Gene expression analysis revealed that two genes of acyltransferases, DGAT1 and DGTT3, were upregulated in the stationary phase of free-living C. debaryana. In addition, the gene expression of these acyltransferases increased earlier in the encapsulated cells than that in the free-living cells. The enhanced production of TAG by alginate gel encapsulation was not found in C. reinhardtii which is known to use a different repertoire of acyltransferases in lipid accumulation.

    更新日期:2020-01-24
  • Genome-Wide Identification of Cassava Serine/Arginine-Rich Proteins: Insights into Alternative Splicing of Pre-mRNAs and Response to Abiotic Stress
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-10-09
    Gu J, Ma S, Zhang Y, et al.

    Serine/arginine-rich (SR) proteins have an essential role in the splicing of pre-messenger RNA (pre-mRNA) in eukaryote. Pre-mRNA with introns can be alternatively spliced to generate multiple transcripts, thereby increasing adaptation to the external stress conditions in planta. However, pre-mRNA of SR proteins can also be alternatively spliced in different plant tissues and in response to diverse stress treatments, indicating that SR proteins might be involved in regulating plant development and adaptation to environmental changes. We identified and named 18 SR proteins in cassava and systematically studied their splicing and transcriptional changes under tissue-specific and abiotic stress conditions. Fifteen out of 18 SR genes showed alternative splicing in the tissues. 45 transcripts were found from 18 SR genes under normal conditions, whereas 55 transcripts were identified, and 21 transcripts were alternate spliced in some SR genes under salt stress, suggesting that SR proteins might participate in the plant adaptation to salt stress. We then found that overexpression of MeSR34 in Arabidopsis enhanced the tolerance to salt stress through maintaining reactive oxygen species homeostasis and increasing the expression of calcineurin B-like proteins (CBL)–CBL-interacting protein kinases and osmotic stress-related genes. Therefore, our findings highlight the critical role of cassava SR proteins as regulators of RNA splicing and salt tolerance in planta.

    更新日期:2020-01-24
  • Far-Red Light Accelerates Photosynthesis in the Low-Light Phases of Fluctuating Light
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-10-16
    Kono M, Kawaguchi H, Mizusawa N, et al.

    It is well known that far-red light (FR; >700 nm) drives PSI photochemistry, but its effect on photosynthetic performance has received little attention. In this study, the effects of the addition of FR to red fluctuating light (FL) have on photosynthesis were examined in the leaves of Arabidopsis thaliana. Light-activated leaves were illuminated with FL [alternating high light/low light (HL/LL) at 800/30 μmol m−2 s−1] for 10–15 min without or with FR at intensities that reflected natural conditions. The CO2 assimilation rates upon the transition from HL to LL were significantly greater with FR than without FR. The enhancement of photosynthesis by FR was small under the steady-state conditions and in the HL phases of FL. Proton conductivity through the thylakoid membrane (gH+) in the LL phases of FL, estimated from the dark relaxation kinetics of the electrochromic absorbance shift, was greater with FR than without FR. The relaxation of non-photochemical quenching (NPQ) in the PSII antenna system and the increase in PSII photochemistry in the LL phases accelerated in the presence of FR. Similar FR-effects in FL were confirmed in typical sun and shade plants. On the basis of these results, we concluded that FR exerted beneficial effects on photosynthesis in FL by exciting PSI and accelerating NPQ relaxation and PSII-yield increase. This was probably because of the increased gH+, which would reflect faster ΔpH dissipation and ATP synthesis.

    更新日期:2020-01-24
  • The Roots of Plant Frost Hardiness and Tolerance
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-10-18
    Ambroise V, Legay S, Guerriero G, et al.

    Frost stress severely affects agriculture and agroforestry worldwide. Although many studies about frost hardening and resistance have been published, most of them focused on the aboveground organs and only a minority specifically targets the roots. However, roots and aboveground tissues have different physiologies and stress response mechanisms. Climate models predict an increase in the magnitude and frequency of late-frost events, which, together with an observed loss of soil insulation, will greatly decrease plant primary production due to damage at the root level. Molecular and metabolic responses inducing root cold hardiness are complex. They involve a variety of processes related to modifications in cell wall composition, maintenance of the cellular homeostasis and the synthesis of primary and secondary metabolites. After a summary of the current climatic models, this review details the specificity of freezing stress at the root level and explores the strategies roots developed to cope with freezing stress. We then describe the level to which roots can be frost hardy, depending on their age, size category and species. After that, we compare the environmental signals inducing cold acclimation and frost hardening in the roots and aboveground organs. Subsequently, we discuss how roots sense cold at a cellular level and briefly describe the following signal transduction pathway, which leads to molecular and metabolic responses associated with frost hardening. Finally, the current options available to increase root frost tolerance are explored and promising lines of future research are discussed.

    更新日期:2020-01-24
  • Male Chromatin Needs to Relax to Get Seeds Started
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-11-07
    Kawashima T.

    Flowering plants reproduce via a complex double fertilization process. Two female gamete cells, the egg cell and the central cell, reside in the ovule. Once fertilized by a sperm cell, they generate the seed embryo and endosperm, respectively (Kawashima and Berger 2011). Unlike the haploid egg cell, the central cell is a homodiploid: two female gametophytic nuclei, known as the polar nuclei, fuse with each other and establish the diploid central cell nucleus. The nuclear envelope consists of inner and outer membranes, and these must combine to complete nuclear fusion. After the male and female gametes fuse (in plasmogamy), the male nucleus migrates toward the female nucleus to undergo gamete nuclear fusion or karyogamy (Fatema et al. 2019). In the model plant Arabidopsis thaliana, several genes have been identified that play a role in fusion of the polar nuclei and mutations in these genes show endosperm developmental defects (Erbasol Serbes et al. 2019); however, until now, it has remained unclear whether the aberrant endosperm phenotype was a direct result of this incorrect fusion. Using a time-lapse live-cell imaging approach, Maruyama et al. (2019) utilized mutants defective in each membrane fusion factor to carefully assess the significance of polar nuclear fusion for the initiation of endosperm development (Fig. 1).

    更新日期:2020-01-24
  • 更新日期:2020-01-24
  • Identification of α-Tomatine 23-Hydroxylase Involved in the Detoxification of a Bitter Glycoalkaloid
    Plant Cell Physiol. (IF 3.929) Pub Date : 2019-12-09
    Nakayasu M, Akiyama R, Kobayashi M, et al.

    Tomato plants (Solanum lycopersicum) contain steroidal glycoalkaloid α-tomatine, which functions as a chemical barrier to pathogens and predators. α-Tomatine accumulates in all tissues and at particularly high levels in leaves and immature green fruits. The compound is toxic and causes a bitter taste, but its presence decreases through metabolic conversion to nontoxic esculeoside A during fruit ripening. This study identifies the gene encoding a 23-hydroxylase of α-tomatine, which is a key to this process. Some 2-oxoglutarate-dependent dioxygenases were selected as candidates for the metabolic enzyme, and Solyc02g062460, designated Sl23DOX, was found to encode α-tomatine 23-hydroxylase. Biochemical analysis of the recombinant Sl23DOX protein demonstrated that it catalyzes the 23-hydroxylation of α-tomatine and the product spontaneously isomerizes to neorickiioside B, which is an intermediate in α-tomatine metabolism that appears during ripening. Leaves of transgenic tomato plants overexpressing Sl23DOX accumulated not only neorickiioside B but also another intermediate, lycoperoside C (23-O-acetylated neorickiioside B). Furthermore, the ripe fruits of Sl23DOX-silenced transgenic tomato plants contained lower levels of esculeoside A but substantially accumulated α-tomatine. Thus, Sl23DOX functions as α-tomatine 23-hydroxylase during the metabolic processing of toxic α-tomatine in tomato fruit ripening and is a key enzyme in the domestication of cultivated tomatoes.

    更新日期:2020-01-24
  • Molecular and genetic bases of heat stress responses in crop plants and breeding for increased resilience and productivity
    J. Exp. Bot. (IF 5.360) Pub Date : 2020-01-23
    Janni M, Gullì M, Maestri E, et al.

    To ensure the food security of future generations and to address the challenge of the “no hunger zone” proposed by the FAO (Food and Agriculture Organization) crop production must be doubled by 2050, but environmental stresses are counteracting this goal. Heat stress in particular is affecting agricultural crops more frequently and more severely. Since the discovery of the physiological, molecular, and genetic bases of heat stress responses, cultivated plants have become the subject of intense research on how they may avoid or tolerate heat stress by using either natural genetic variation or creating new variation with DNA technologies, mutational breeding, or genome editing. This review reports the current understanding of the genetic and molecular bases of heat stress in crops together with recent approaches to creating heat-tolerant varieties. Research is close to a breakthrough of global relevance, breeding plants fitter to face the biggest challenge of our time.

    更新日期:2020-01-24
  • Leaf hydraulic conductance is linked to leaf symmetry in bifacial, amphistomatic leaves of Sunflower
    J. Exp. Bot. (IF 5.360) Pub Date : 2020-01-23
    Richardson F, Jordan G, Brodribb T.

    The hydraulic implications of stomatal positioning across leaf surfaces and the impact on internal water flow through amphistomatic leaves are not currently well understood. Amphistomaty potentially provides hydraulic efficiencies if the majority of hydraulic resistance in the leaf exists outside the xylem in the mesophyll. Such a scenario would mean that the same xylem network could equally supply a hypostomatic or amphistomatic leaf. Here we examine leaves of Helianthus annuus to determine whether amphistomaty in this species is associated with higher hydraulic efficiency compared with hypostomatic leaves. We identified asymmetry in the positioning of minor veins which were significantly closer to the abaxial than the adaxial leaf surface combined with lower Kleaf when transpiration was driven through the adaxial rather than abaxial surface. We also identified a degree of coordination in stomatal behaviour driven by leaf hydraulics, where the hydraulic conditions experienced by an individual leaf surface affected the stomatal behaviour on the opposite surface. We found no advantage to amphistomaty based on efficiencies in construction costs of the venous system, represented by vein density:stomatal density, only limited hydraulic independence between leaf surfaces. These results suggest that amphistomaty does not substantially increase whole-leaf hydraulic efficiency.

    更新日期:2020-01-24
  • Signaling pathways underlying nitrogen-dependent changes in root system architecture: from model to crop species
    J. Exp. Bot. (IF 5.360) Pub Date : 2020-01-23
    Jia Z, Wirén N.

    Among all essential mineral elements, nitrogen (N) is required in largest amounts and thus often a limiting factor for plant growth. Nitrogen is taken up by plant roots in the form of water-soluble nitrate, ammonium and, depending on abundance, low-molecular weight organic N. In soils, the availability and composition of these N forms can vary over space and time, which exposes roots to various local N signals that regulate root system architecture in combination with systemic signals reflecting the N nutritional status of the shoot. Uncovering the molecular mechanisms underlying N-dependent signalling provides great potential to optimize root system architecture for the sake of higher N uptake efficiency in crop breeding. In this review, we summarize prominent signalling mechanisms and their underlying molecular players that derive from external N forms or the internal N nutritional status and modulate root development including root hair formation and gravitropism. The current state of knowledge on these pathways is compared between Arabidopsis and graminaceous plant species.

    更新日期:2020-01-24
  • RETRACTION NOTICE
    J. Exp. Bot. (IF 5.360) Pub Date : 2020-01-23

    Following concerns expressed by a reader, the Editor-in-Chief and Publisher of Journal of Experimental Botany have taken the decision to retract the following papers. The articles are retracted due to concern over image manipulation and duplication.

    更新日期:2020-01-24
  • Endomembrane architecture and dynamics during secretion of the extracellular matrix of the unicellular charophyte, Penium margaritaceum
    J. Exp. Bot. (IF 5.360) Pub Date : 2020-01-24
    Domozych D, Sun L, Palacio-Lopez K, et al.

    The extracellular matrix (ECM) of many charophytes, the assemblage of green algae that are the sister group to land plants, is complex, produced in large amounts and has multiple essential functions. An extensive secretory apparatus and endomembrane system are presumably needed to synthesize and secrete the ECM, but structural details of such a system have not been fully characterized. Penium margaritaceum is a valuable unicellular model charophyte for studying secretion dynamics. We report that Penium has a highly organized endomembrane system, consisting of 150-200 non-mobile Golgi bodies that process and package ECM components into different sets of vesicles that traffic to the cortical cytoplasm, where they are transported around the cell by cytoplasmic streaming. At either fixed or transient areas, specific cytoplasmic vesicles fuse with the plasma membrane and secrete their constituents. EPS production was observed to occur in one location of the Golgi body and sometimes in unique Golgi hybrids. Treatment of cells with brefeldin A caused disruption of the Golgi body, inhibition of EPS secretion and cell wall expansion. The structure of the endomembrane system in Penium provides mechanistic insights into how extant charophytes generate large quantities of ECM, which in their ancestors facilitated the colonization of land.

    更新日期:2020-01-24
  • Symplasmic Isolation Marks Cell Fate Changes During Somatic Embryogenesis
    J. Exp. Bot. (IF 5.360) Pub Date : 2020-01-24
    Godel-Jedrychowska K, Kulinska-Lukaszek K, Horstman A, et al.

    Cell-to-cell signalling is a major mechanism controlling plant morphogenesis. Transport of signalling molecules through plasmodesmata (PD) is one way in which plants promote or restrict intercellular signalling over short distances. PD are membrane lined pores between cells that regulate the intercellular flow of signalling molecules through changes in their size, creating symplasmic fields of connected cells. Here we examined the role of PD and symplasmic communication in the establishment of plant cell totipotency, using somatic embryo induction from Arabidopsis (Arabidopsis thaliana) explants as a model system. Cell-to-cell communication was evaluated using fluorescent tracers, supplemented with histological and ultrastructural analysis, and correlated with expression of a WOX2 embryo reporter. We show that embryogenic cells are isolated symplasmically from non-embryogenic cells regardless of the explant type (immature zygotic embryos or seedlings) and inducer system [2,4-dichlorophenoxyacetic acid (2,4-D) or the BABY BOOM (BBM) transcription factor], but that the symplasmic domains in different explants differ with respect to the maximum size of molecules capable of moving through the PD. Callose deposition in PD preceded WOX2 expression in future sites of somatic embryo development, but later, was greatly reduced in WOX2-expressing domains. Callose deposition was also associated with a decrease DR5 auxin response in embryogenic tissue. Treatment of explants with the callose biosynthesis inhibitor 2-deoxy-D-glucose supressed somatic embryo formation in all three systems studied, and also blocked the observed decrease in DR5expression. Together this data suggests that callose deposition at PD is required for symplasmic isolation and establishment of cell totipotency in Arabidopsis.

    更新日期:2020-01-24
  • Regulation of flowering transition by alternative splicing: the role of the U2 auxiliary factor.
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-13
    Yu-Yi Wang,Feng Xiong,Qiu-Ping Ren,Xiu-Ling Wang

    Flowering transition is regulated by complex genetic networks in response to endogenous and environmental signals. Pre-mRNA splicing is an essential step for the post-transcriptional regulation of gene expression. Alternative splicing of key flowering genes has been investigated in detail over the past decade. However, few splicing factors have been identified as being involved in flowering transition. Human heterodimeric splicing factor U2 snRNP auxiliary factor (U2AF) consists of two subunits, U2AF35 and U2AF65, and functions in 3' splice site recognition in mRNA splicing. Recent studies reveal that Arabidopsis U2AF65a/b and U2AF35a/b play important roles in the splicing of key flowering genes. We summarize recent advances in research on splicing-regulated flowering transition by focusing on the role of Arabidopsis U2AF in the splicing of key flowering-related genes at ambient temperature and in the abscisic acid signaling pathways.

    更新日期:2020-01-24
  • Histone tales: lysine methylation, a protagonist in Arabidopsis development.
    J. Exp. Bot. (IF 5.360) Pub Date : null
    Kai Cheng,Yingchao Xu,Chao Yang,Luc Ouellette,Longjian Niu,Xiaochen Zhou,Liutian Chu,Feng Zhuang,Jin Liu,Hualing Wu,Jean-Benoit Charron,Ming Luo

    Histone methylation plays a fundamental role in the epigenetic regulation of gene expression driven by developmental and environmental cues in plants, including Arabidopsis. Histone methyltransferases and demethylases act as "writers" and "erasers" of methylation at lysine and/or arginine residues of core histones, respectively. A third group of proteins, the "readers", recognize and interpret the methylation marks. Emerging evidences confirm the crucial roles of histone methylation in multiple biological processes throughout plant life cycle. In this review, we summarize the regulatory mechanisms of lysine methylation, especially at histone H3 tails, and focus on the recent advances regarding the roles of lysine methylation in Arabidopsis development, from seed performance to reproductive development, and in callus formation.

    更新日期:2020-01-24
  • Interplay between turgor pressure and plasmodesmata during plant development
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-09-29
    Hernández-Hernández V, Benítez M, Boudaoud A, et al.

    Plasmodesmata traverse cell walls, generating connections between neighboring cells. They allow intercellular movement of molecules such as transcription factors, hormones, and sugars, and thus create a symplasmic continuity within a tissue. One important factor that determines plasmodesmal permeability is their aperture, which is regulated during developmental and physiological processes. Regulation of aperture has been shown to affect developmental events such as vascular differentiation in the root, initiation of lateral roots, or transition to flowering. Extensive research has unraveled molecular factors involved in the regulation of plasmodesmal permeability. Nevertheless, many plant developmental processes appear to involve feedbacks mediated by mechanical forces, raising the question of whether mechanical forces and plasmodesmal permeability affect each other. Here, we review experimental data on how one of these forces, turgor pressure, and plasmodesmal permeability may mutually influence each other during plant development, and we discuss the questions raised by these data. Addressing such questions will improve our knowledge of how cellular patterns emerge during development, shedding light on the evolution of complex multicellular plants.

    更新日期:2020-01-24
  • In silico study of the role of cell growth factors on photosynthesis using a virtual leaf tissue generator coupled to a microscale photosynthesis gas exchange model.
    J. Exp. Bot. (IF 5.360) Pub Date : null
    M A Retta,M K Abera,H N C Berghuijs,P Verboven,P C Struik,B M Nicolaï

    Computational tools that allow in silico analysis of the role of cell growth and division on photosynthesis are scarce. We present a freely available tool that combines a virtual leaf tissue generator and a two-dimensional microscale model of gas transport during C3 photosynthesis. A total of 270 mesophyll geometries were generated with varying degree of growth anisotropy, growth extent and extent of schizogenous airspace formation in the palisade mesophyll. The anatomical properties of the virtual leaf tissue and microscopic cross sections of actual leaf tissue of tomato (Solanum lycopersicum L.) were statistically compared. Model equations for transport of CO2 in the liquid phase of the leaf tissue were discretized over the geometries. The virtual leaf tissue generator produced a leaf anatomy of tomato that was statistically similar to real tomato leaf tissue. The response of photosynthesis to intercellular CO2 predicted by a model that used the virtual leaf tissue geometry compared well with measured values. The results indicate that the light-saturated rate of photosynthesis was influenced by interactive effects of extent and directionality of cell growth and degree of airspace formation through the exposed surface of mesophyll per leaf area. The tool could be used further in investigations of improving photosynthesis and gas exchange in relation to cell growth and leaf anatomy.

    更新日期:2020-01-24
  • The small GTPase Rab5a and its guanine nucleotide exchange factors are involved in post-Golgi trafficking of storage proteins in developing soybean cotyledon
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-16
    Wei Z, Pan T, Zhao Y, et al.

    Storage protein is the most abundant nutritional component in soybean seed. Morphology-based evidence has verified that storage proteins are initially synthesized on the endoplasmic reticulum, and then follow the Golgi-mediated pathway to the protein storage vacuole. However, the molecular mechanisms of storage protein trafficking in soybean remain unknown. Here, we clone the soybean homologs of Rab5 and its guanine nucleotide exchange factor (GEF) VPS9. GEF activity combined with yeast two-hybrid assays demonstrated that GmVPS9a2 might specifically act as the GEF of the canonical Rab5, while GmVPS9b functions as a common activator for all Rab5s. Subcellular localization experiments showed that GmRab5a was dually localized to the trans-Golgi network and pre-vacuolar compartments in developing soybean cotyledon cells. Expression of a dominant negative variant of Rab5a, or RNAi of either Rab5a or GmVPS9s, significantly disrupted trafficking of mRFP–CT10, a cargo marker for storage protein sorting, to protein storage vacuoles in maturing soybean cotyledons. Together, our results systematically revealed the important role of GmRab5a and its GEFs in storage protein trafficking, and verified the transient expression system as an efficient approach for elucidating storage protein trafficking mechanisms in seed.

    更新日期:2020-01-24
  • Redox homeostasis in the growth zone of the rice leaf plays a key role in cold tolerance
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-18
    Gázquez A, Abdelgawad H, Baggerman G, et al.

    We analysed the cellular and molecular changes in the leaf growth zone of tolerant and sensitive rice varieties in response to suboptimal temperatures. Cold reduced the final leaf length by 35% and 51% in tolerant and sensitive varieties, respectively. Tolerant lines exhibited a smaller reduction of the leaf elongation rate and greater compensation by an increased duration of leaf growth. Kinematic analysis showed that cold reduced cell production in the meristem and the expansion rate in the elongation zone, but the latter was compensated for by a doubling of the duration of cell expansion. We performed iTRAQ proteome analysis on proliferating and expanding parts of the leaf growth zone. We identified 559 and 542 proteins, of which 163 and 210 were differentially expressed between zones, and 96 and 68 between treatments, in the tolerant and sensitive lines, respectively. The categories protein biosynthesis and redox homeostasis were significantly overrepresented in the up-regulated proteins. We therefore measured redox metabolites and enzyme activities in the leaf growth zone, demonstrating that tolerance of rice lines to suboptimal temperatures correlates with the ability to up-regulate enzymatic antioxidants in the meristem and non-enzymatic antioxidants in the elongation zone.

    更新日期:2020-01-24
  • AKINβ1, a subunit of SnRK1, regulates organic acid metabolism and acts as a global modulator of genes involved in carbon, lipid, and nitrogen metabolism
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-18
    Wang Y, Wang L, Micallef B, et al.

    The sucrose non-fermenting-1-related protein kinase 1 (SnRK1) is a highly conserved heterotrimeric protein kinase in plants. It possesses a catalytic subunit (α) and two regulatory subunits (β and γ). The effects of altered expression of AKINβ1 on carbohydrate metabolism and gene expression in leaves were investigated in an Arabidopsis T-DNA insertion mutant. The contents of key intermediates in the tricarboxylic acid (TCA) cycle of the mutant leaves were markedly reduced throughout the diurnal cycle, coupled with a decrease in measurable respiration rate. Compared with the wild type, 2485 genes and 188 genes were differentially expressed in leaves of the akinβ1 mutant in response to light and darkness, respectively. Among these, several genes exhibited very substantial decreases in expression. Notably, expression of particular isoforms of multigene families involved in malate and lipid metabolism and nitrate uptake showed decreases of 40- to 240-fold during the light period, but not during darkness. The subcellular localization of AKINβ1 and the regulatory function of N-myristoylation for this localization were investigated, showing that AKINβ1 localizes to the Golgi. A model is hypothesized to explain the effects of AKINβ1 on metabolism and gene expression in Arabidopsis.

    更新日期:2020-01-24
  • Transcription factor CaNAC1 regulates low-temperature-induced phospholipid degradation in green bell pepper
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-18
    Kong X, Zhou Q, Zhou X, et al.

    Phospholipids constitute the main component of biomembranes. During low-temperature storage and transportation of harvested bell peppers (Capsicum annuum), chilling injury participates in their decay. A primary cause of this chilling injury is phospholipid degradation. In this study, three genes encoding phospholipase D (PLD) were identified from bell peppers and their activities were examined under cold stress. Low temperature (4 °C) induced strong accumulation of the CaPLDα4 transcript, suggesting that it is associated with the phenomenon of phospholipid degradation and destruction of cell membranes. Low temperature also significantly induced increased amounts of NAM-ATAF1/2-CUC2 (NAC) domain transcription factors. CaNAC1 was found to interact with the promoter of CaPLD4 in a yeast one-hybrid screen. Electrophoretic mobility shift and ß-glucuronidase reporter assays demonstrated that CaNAC1 binds to the CTGCAG motif in the CaPLDα4 promoter, thereby activating its transcription and controlling phospholipid degradation. The ubiquitination sites of the CaNAC1 protein were characterized by liquid chromatography–tandem mass spectrometry. We conclude that CaNAC1 is a transcriptional activator of CaPLDα4 and suggested that it participates in the degradation of membrane lipids in bell peppers when they are stored at low temperature.

    更新日期:2020-01-24
  • Robust non-syntenic gene expression patterns in diverse maize hybrids during root development
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-22
    Baldauf J, Vedder L, Schoof H, et al.

    Distantly related maize (Zea mays L.) inbred lines exhibit an exceptional degree of structural genomic diversity, which is probably unique among plants. This study systematically investigated the developmental and genotype-dependent regulation of the primary root transcriptomes of a genetically diverse panel of maize F1-hybrids and their parental inbred lines. While we observed substantial transcriptomic changes during primary root development, we demonstrated that hybrid-associated gene expression patterns, including differential, non-additive, and allele-specific transcriptome profiles, are particularly robust to these developmental fluctuations. For instance, differentially expressed genes with preferential expression in hybrids were highly conserved during development in comparison to their parental counterparts. Similarly, in hybrids a major proportion of non-additively expressed genes with expression levels between the parental values were particularly conserved during development. Importantly, in these expression patterns non-syntenic genes that evolved after the separation of the maize and sorghum lineages were systemically enriched. Furthermore, non-syntenic genes were substantially linked to the conservation of all surveyed gene expression patterns during primary root development. Among all F1-hybrids, between ~40% of the non-syntenic genes with unexpected allelic expression ratios and ~60% of the non-syntenic differentially and non-additively expressed genes were conserved and therefore robust to developmental changes. Hence, the enrichment of non-syntenic genes during primary root development might be involved in the developmental adaptation of maize roots and thus the superior performance of hybrids.

    更新日期:2020-01-24
  • Submergence stress-induced hypocotyl elongation through ethylene signaling-mediated regulation of cortical microtubules in Arabidopsis
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-22
    Wang X, Ma Q, Wang R, et al.

    Plant growth is significantly altered in response to submergence stress. However, the molecular mechanisms used by seedlings in response to this stress, especially for hypocotyl growth, are largely unknown in terrestrial plants such as Arabidopsis thaliana. The microtubule cytoskeleton participates in plant cell growth, but it remains unclear whether submergence-mediated plant growth involves the microtubule cytoskeleton. We demonstrated that in Arabidopsis submergence induced underwater hypocotyl elongation through the activation of ethylene signaling, which modulated cortical microtubule reorganization. Submergence enhanced ethylene signaling, which then activated and stabilized its downstream transcription factor, phytochrome-interacting factor 3 (PIF3), to promote hypocotyl elongation. In particular, the regulation of microtubule organization was important for this physiological process. Microtubule-destabilizing protein 60 (MDP60), which was previously identified as a downstream effector of PIF3, played a positive role in submergence-induced hypocotyl elongation. Submergence induced MDP60 expression through ethylene signaling. The effects of submergence on hypocotyl elongation and cortical microtubule reorganization were suppressed in mdp60 mutants. These data suggest a potential mechanism by which submergence activates ethylene signaling to promote underwater hypocotyl elongation via alteration of the microtubule cytoskeleton in Arabidopsis.

    更新日期:2020-01-24
  • Diverse trajectories of plastome degradation in holoparasitic Cistanche and genomic location of the lost plastid genes
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-23
    Liu X, Fu W, Tang Y, et al.

    The plastid genomes (plastomes) of non-photosynthetic plants generally undergo gene loss and pseudogenization. Despite massive plastomes reported in different parasitism types of the broomrape family (Orobanchaceae), more plastomes representing different degradation patterns in a single genus are expected to be explored. Here, we sequence and assemble the complete plastomes of three holoparasitic Cistanche species (C. salsa, C. mongolica, and C. sinensis) and compare them with the available plastomes of Orobanchaceae. We identified that the diverse degradation trajectories under purifying selection existed among three Cistanche clades, showing obvious size differences in the entire plastome, long single copy region, and non-coding region, and different patterns of the retention/loss of functional genes. With few exceptions of putatively functional genes, massive plastid fragments, which have been lost and transferred into the mitochondrial or nuclear genomes, are non-functional. In contrast to the equivalents of the Orobanche species, some plastid-derived genes with diverse genomic locations are found in Cistanche. The early and initially diverged clades in different genera such as Cistanche and Aphyllon possess obvious patterns of plastome degradation, suggesting that such key lineages should be considered prior to comparative analysis of plastome evolution, especially in the same genus.

    更新日期:2020-01-24
  • Sigma factor 1 in chloroplast gene transcription and photosynthetic light acclimation
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-23
    Macadlo L, Ibrahim I, Puthiyaveetil S, et al.

    Sigma factors are dissociable subunits of bacterial RNA polymerase that ensure efficient transcription initiation from gene promoters. Owing to their prokaryotic origin, chloroplasts possess a typical bacterial RNA polymerase together with its sigma factor subunit. The higher plant Arabidopsis thaliana contain as many as six sigma factors for the hundred or so of its chloroplast genes. The role of this relatively large number of transcription initiation factors for the miniature chloroplast genome, however, is not fully understood. Using two Arabidopsis T-DNA insertion mutants, we show that sigma factor 1 (SIG1) initiates transcription of a specific subset of chloroplast genes. We further show that the photosynthetic control of PSI reaction center gene transcription requires complementary regulation of the nuclear SIG1 gene at the transcriptional level. This SIG1 gene regulation is dependent on both a plastid redox signal and a light signal transduced by the phytochrome photoreceptor.

    更新日期:2020-01-24
  • CIRCADIAN CLOCK ASSOCIATED 1 and ATAF2 differentially suppress cytochrome P450-mediated brassinosteroid inactivation
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-23
    Peng H, Neff M, Napier R.

    Brassinosteroids (BRs) are a group of steroid hormones regulating plant growth and development. Since BRs do not undergo transport among plant tissues, their metabolism is tightly regulated by transcription factors (TFs) and feedback loops. BAS1 (CYP734A1, formerly CYP72B1) and SOB7 (CYP72C1) are two BR-inactivating cytochrome P450s identified in Arabidopsis thaliana. We previously found that a TF ATAF2 (ANAC081) suppresses BAS1 and SOB7 expression by binding to the Evening Element (EE) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1)-binding site (CBS) on their promoters. Both the EE and CBS are known binding targets of the circadian regulatory protein CCA1. Here, we confirm that CCA1 binds the EE and CBS motifs on BAS1 and SOB7 promoters, respectively. Elevated accumulations of BAS1 and SOB7 transcripts in the CCA1 null mutant cca1-1 indicate that CCA1 is a repressor of their expression. When compared with either cca1-1 or the ATAF2 null mutant ataf2-2, the cca1-1 ataf2-2 double mutant shows higher SOB7 transcript accumulations and a stronger BR-insensitive phenotype of hypocotyl elongation in white light. CCA1 interacts with ATAF2 at both DNA–protein and protein–protein levels. ATAF2, BAS1, and SOB7 are all circadian regulated with distinct expression patterns. These results demonstrate that CCA1 and ATAF2 differentially suppress BAS1- and SOB7-mediated BR inactivation.

    更新日期:2020-01-24
  • Brassinosteroids act as a positive regulator of NBR1-dependent selective autophagy in response to chilling stress in tomato
    J. Exp. Bot. (IF 5.360) Pub Date : 2019-10-23
    Chi C, Li X, Fang P, et al.

    Autophagy is a highly conserved and regulated catabolic process involved in the degradation of protein aggregates, which plays critical roles in eukaryotes. In plants, multiple molecular processes can induce or suppress autophagy but the mechanism of its regulation by phytohormones is poorly understood. Brassinosteroids (BRs) are steroid phytohormones that play crucial roles in plant response to stresses. Here, we investigate the role of BRs in NBR1-dependent selective autophagy in response to chilling stress in tomato. BRs and their signaling element BZR1 can induce autophagy and accumulation of the selective autophagy receptor NBR1 in tomato under chilling stress. Cold increased the stability of BZR1, which was promoted by BRs. Cold- and BR-induced increased BZR1 stability activated the transcription of several autophagy-related genes (ATGs) and NBR1 genes by directly binding to their promoters, which resulted in selective autophagy. Furthermore, silencing of these ATGs or NBR1 genes resulted in a decreased accumulation of several functional proteins and an increased accumulation of ubiquitinated proteins, subsequently compromising BR-induced cold tolerance. These results strongly suggest that BRs regulate NBR1-dependent selective autophagy in a BZR1-dependent manner in response to chilling stress in tomato.

    更新日期:2020-01-24
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