Boron deficiency disorders the cell wall in Neolamarckia cadamba

https://doi.org/10.1016/j.indcrop.2021.114332Get rights and content

Highlights

  • B deficiency induced morphological and RNA transcriptome changes in N. cadamba.

  • B deficiency reduced seedling growth, inhibit shoot tip growth and leaf shape.

  • The phenylalanine ammonia lyase and phenylpropanoid biosynthesis pathways increased under B deficiency.

  • Pectin content decreased and the expression levels of pectin genes respond to B deficiency.

  • B transporter BOR1 was differentially over-expressed under B deficiency in different tissues.

Abstract

Boron (B) is an essential element for plant growth and development as it regulates numerous biological processes. Despite years of research on the role of B in regulating plant growth, changes in cell wall composition due to B deficiencyremain unclear. Here, we study B deficiency on the physiology and transcriptome of Neolamarckia cadamba, a fast-growing woody plant with diverse applications. B deficiency induces severe morphological and anatomical changes in N. cadamba including reduced seedling growth, significant inhibition of shoot tip growth and leaves. B deficiency also resulted in oxidative damage and decreasing B concentration in plant. In addition, enhancing activation of the phenylalanine ammonia lyase (PAL) and phenylpropanoid biosynthesis pathways resulted in increased shoot tip lignification. Pectin content decreased and the genes related to the synthesis of pectin and cellulose in mature leaves of N. cadamba changed expression levels in response to B deficiency. Moreover, BOR1, a potential B transporter, was differentially over-expressed under B deficiency in different tissues. Taking together, we can conclude that adaptive changes in N. cadamba cell walls to respond to B deficiency can potentially be utilized for genetic engineering and breeding for low B tolerance.

Introduction

Neolamarckia cadamba (Roxb.) Bosser is a multifunctional, fast-growing tree species that is widely used as a type of medicine in some Asian countries (Ouyang et al., 2016). Recent transcriptome-based studies and structural analysis have provided insight into the characterization of heteroxylan biosynthesis and woody tissue formation in N. cadamba (Zhao et al., 2014, Zhao et al., 2017).

Boron (B) was classified as an essential element in 1923 (Warington, 1923), and the demand for B varies between different plants and even different tissues. B demand in plants is trace, but B deficiency usually induces incurable symptoms. Representative symptoms induced by B deficiency include stunted growth, swelling growing tips, death of growing tips in severe cases, and curled leaves with yellow spotting (Matoh, 1997, Brown et al., 2008). All these changes severely impact both the quality and production of commercially important plants (Brown et al., 2002). Overall cell wall changes under B deficiency in timber plant are still rarely reported.

Nearly 90% of cellular B is positioned on the cell wall (Loomis and Durst, 1992), and nearly four-fifths of the cell wall B is just bound to polysaccharides containing cis diol substrates (Matoh, 1997). It is well known that B influences the mechanical properties of intercellular pectins. Two chains of monomeric RGII, Ca2+, and two molecules of B make a covalent complex B-RGII as a part of pectins structure that affects cell-to-cell adhesion (Loomis and Durst, 1992, Matoh, 1997, O'Neill et al., 2004). UDP-D-apiose/UDP-D-xylose synthase (AXS) which is participated in regulating apiose content plays an important role in RGII cross-linking with B. The Arabidopsis axs1 axs2/+ mutant contains less B-RGII dimers (Zhao et al., 2020), and AXS1-silenced plants by virus induced gene silencing (VIGS) are dwarfed (Ahn et al., 2006), indicating that B-RGII is vital for normal morphogenesis. Pectin hydrolases, polygalacturonases, pectin lyase, and pectin methyl esterase biodegrade glycosidic bonds of pectic substances and disintegrate the cell wall (Fogarty and Kelly, 1983), which led to altered expression in the Arabidopsis axs1 axs2/+ mutant (Zhao et al., 2020). Recent studies reveal the RHAMNOGALACTURONAN XYLOSYLTRANSFERASE (RGXT) family including RGXT1, RGXT2 and RGXT3 possess α-1, 3-xylosyltransferase activity and can transfer Xyl from UDP-Xyl onto Fuc, and this linkage is peculiar to RGII (Petersen et al., 2009, Harholt et al., 2010). The influence of B-RGII to RGXT is still unclear. B-bridging implicates other pectic composition changes, which was needed.

B may also be required for lignin biosynthesis according to the land plants origin and numerous studies (Kutschera and Niklas, 2017, Lewis, 1980). Lignin, the second most abundant polymer in plant cell walls, is synthesized by the conversion of phenylalanine to cinnamate and a series of methylations, hydroxylations and oxidation. Plants under B deficiency have lignification and thick cell walls (Dutta and McIlrath, 1964, Slack and Whittington, 1964). The plant cell wall is an unbroken structure, and its integrity can affect disease resistance. Cellulose is the most characteristic, and is involved in differential defence responses (Bacete et al., 2018). For example, Arabidopsis cellulose synthase CESA4, CESA7, and CESA8 have been shown to enhance resistance to different pathogens (Desprez et al., 2007, Escudero et al., 2017, Hernández-Blanco et al., 2007).

As a movable element, B transporters fall into two groups. One group consists of BORs exporting B from cell to cell, and the other group consists of NIPs which enhance bidirectional permeability (Sotta et al., 2017). Transport protein levels seem to depend on B concentration. While it is now clear that the borate receptor BOR1/2 may have partially similar pathways to perform its function, it is not yet clear whether there are any analogous mechanisms in woody plants.

In this study, we investigate nutrient content and antioxidant enzyme activities in leaves of Neolamarckia cadamba growing under B deficiency. Next, we study the lignification of the first internode. Water-soluble pectin content and gene expression patterns of pectin biosynthesis and degradation show B deficiency cause pectin content to decrease. We also find that cellulose biosynthesis also changes with B deficiency. Our research confirms that B deficiency not only affects pectin (B-RGII), but also the other cell wall components lignin and cellulose in N. cadamba.

Section snippets

Plant materials and culture

To ensure consistency and clarity between experiments, plantlets of Neolamarckia cadamba were cultured by tissue culture. Three-month-old plantlets were grown in Hoagland’s nutrient cultured solution in distilled water supplemented with the following concentrations of macro- and micro-nutrients; 1.6 mmol L-1 (mM) Ca (NO3)2, 2.4 mM KNO3, 0.8 mM MgSO4, 0.4 mM NH4H2PO4, 38 μmol L-1 (μΜ) MnSO4, 0.32 μM ZnSO4, 0.12 μM CuSO4, 0.008 μM (NH4)6Mo7O24 and 32 μM FeNa-EDTA, as B0. The experimental setup

B deficiency exhibited effects on plant growth and morphology

In order to examine B function in N. cadamba growth, three-month-old seedlings were treated on Hydroponics Hoagland’s nutrient cultured solution system without B (B0) and with 20 μM B (B20). Compared to B20, B0 severely hampered the growth of vegetative morphology (stems, shoot tips and leaves) in N. cadamba. Plantlets grown on B deficiency culture solution were shorter than those in B20 (Fig. 1A). These had partially thick and black stems with withered shoot tips due to cell death (Fig. 1B),

Discussion

Although B is a micro-element of plants, it plays an indispensable role in regulating plant metabolism and growth (Papadakis et al., 2018, Riaz et al., 2018). It is very difficult to explore the impact of B deficiency effects on plant development, especially for wood. Growing trees in a hydroponic system makes it possible to study the mechanism of B effects on wood plants by comparing physiology analysis, cell wall composition, ionic concentration, osmotic pressure, nutritive elements and gene

Conclusions

Based on morpho-physiological observations and assays, biophysical examinations and transcriptional analyses, our results illustrate that cell wall lignification, changes of pectin and up-regulation of cellulose genes occurs in response to B deficiency in N. cadamba. Decreased pectin concentration as well as up-regulation of genes encoding PG and BGAL indicate that B deficiency directly impacts pectin in N. cadamba. Furthermore, up-regulation of cellulose synthase genes provides a new basis to

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

Financial support for this work was obtained by Key Project of Guangzhou Science and Technology Plan (201904020014), China and the National Natural Science Foundation of China (Grant Numbers 31870653, 31670670, 31811530009, 31670601).

Authors’ contributions

A. W. and X. D. design the experiments; Q.Y. and W. Q. analyzed the data and wrote the manuscript; L. K., Y. L. and T. L. performed the experimrnts; H.L.and F. M. revised the language of the manuscript.

CRediT authorship contribution statement

Qi Yin: Data curation, Methodology, Writing − original draft. Lu Kang: Data curation, Methodology. Yi Liu: Data curation, Methodology. Mirza Faisal Qaseem: Data curation, Methodology. Wenqi Qin: Data curation, Writing − original draft. Tingting Liu: Data curation, Methodology. Huiling Li: Data curation, Methodology, Writing, Conceptualization, Supervision. Xiaomei Deng, Ai-Min Wu: Conceptualization, Supervision, Project administration, Writing − review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References (46)

  • S. Anders et al.

    HTSeq-a Python framework to work with high-throughput sequencing data

    Bioinformatics

    (2014)
  • L. Bacete et al.

    Plant cell wall-mediated immunity: cell wall changes trigger disease resistance responses

    Plant J.

    (2018)
  • P.H. Brown et al.

    Boron in plant biology

    Plant Biol.

    (2008)
  • T. Desprez et al.

    Organization of cellulose synthase complexes involved in primary cell wall synthesis in Arabidopsis thaliana

    Proc. Natl. Acad. Sci.

    (2007)
  • T.R. Dutta et al.

    Effects of boron on growth and lignification in sunflower tissue and organ cultures

    Bot. Gaz.

    (1964)
  • C. Ellis et al.

    The Arabidopsis mutant cev1 links cell wall signaling to jasmonate and ethylene responses

    Plant Cell

    (2002)
  • V. Escudero et al.

    Alteration of cell wall xylan acetylation triggers defense responses that counterbalance the immune deficiencies of plants impaired in the β‐subunit of the heterotrimeric G‐protein

    Plant J.

    (2017)
  • W.M. Fogarty et al.

    Pectic enzymes

  • J. Harholt et al.

    Biosynthesis of Pectin

    Plant Physiol.

    (2010)
  • C. Hernández-Blanco et al.

    Impairment of cellulose synthases required for Arabidopsis secondary cell wall formation enhances disease resistance

    Plant Cell

    (2007)
  • B.D. Kohorn et al.

    Pectin activation of MAP kinase and gene expression is WAK2 dependent

    Plant J.

    (2009)
  • U. Kutschera et al.

    Boron and the evolutionary development of roots

    Plant Signal. Behav.

    (2017)
  • D.H. Lewis

    Boron, lignification and the origin of vascular plants -a unified hypothesis

    N. Phytol.

    (1980)
  • Cited by (9)

    • Activation tagging identifies WRKY14 as a repressor of plant thermomorphogenesis in Arabidopsis

      2022, Molecular Plant
      Citation Excerpt :

      The diluted cDNA was used to perform semi-RT–PCR or qRT–PCR with the specific primers listed in Supplemental Table 7. qRT–PCR was performed with three biological repeats using SYBR Premix Ex Taq II (TaKaRa) and a LightCycler 480 Real-Time PCR System (Roche, Switzerland) (Yin et al., 2022). The qRT–PCR conditions were as follows: 95°C for 2 min followed by 35–40 cycles of 94°C for 10 s, 55°C for 20 s, and 72°C for 20 s.

    • Metabolomics of nutrient-deprived forest trees

      2024, Monitoring Forest Damage with Mass Spectrometry-Based Metabolomics Methods
    View all citing articles on Scopus
    View full text