Cell Wall Proteome in the Maize Primary Root Elongation Zone. II. Region-Specific Changes in Water Soluble and Lightly Ionically Bound Proteins under Water Deficit

The ultrastructure and morphology of roots treated with coumarin and umbelliferone as well as the reversibility of the coumarins effects caused by exogenous GA, were studied in <em>Arabidopsis thaliana</em>. Both coumarins suppressed root elongation and appreciably stimulated radial expansion of epidermal and cortical cells in the upper part of the meristem and in the elongation zone. The gibberellic acid applied simultaneously with coumarins decreased their inhibitory effect on root elongation and reduced cells swelling.Microscopic observation showed intensive vacuolization of cells and abnormalities in the structure of the Golgi stacks and the nuclear envelope. The detection of active acid phosphatase in the cytosol of swollen cells indicated increased membrane permeability. Significant abnormalities of newly formed cell walls, e.g. the discontinuity of cellulose layer, uncorrect position of walls and the lack of their bonds with the mother cell wall suggest that coumarins affected the cytoskeleton.

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Water Deficit Rapidly Stimulates the Activity of a Protein Kinase in the Elongation Zone of the Maize Primary Root

PLANT PHYSIOLOGY ◽

10.1104/pp.113.1.219 ◽

1997 ◽

Vol 113 (1) ◽

pp. 219-226 ◽

Cited By ~ 14

Author(s):

T. R. Conley ◽

R. E. Sharp ◽

J. C. Walker

Keyword(s):

Protein Kinase ◽

Water Deficit ◽

Primary Root ◽

Elongation Zone

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Differential expression of cell wall related genes in the elongation zone of rice roots under water deficit

Russian Journal of Plant Physiology ◽

10.1134/s1021443706030150 ◽

2006 ◽

Vol 53 (3) ◽

pp. 390-395 ◽

Cited By ~ 30

Author(s):

L. Yang ◽

C. C. Wang ◽

W. D. Guo ◽

X. B. Li ◽

M. Lu ◽

...

Keyword(s):

Cell Wall ◽

Differential Expression ◽

Water Deficit ◽

Elongation Zone ◽

Rice Roots

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Apical-root apoplastic acidification affects cell-wall extensibility in wheat under salinity stress

10.1101/2020.10.20.347310 ◽

2020 ◽

Author(s):

Yang Shao ◽

Xiaohui Feng ◽

Hiroki Nakahara ◽

Muhammad Irshad ◽

A. Egrinya Eneji ◽

...

Keyword(s):

Cell Wall ◽

Root Growth ◽

Salinity Stress ◽

Root Elongation ◽

Elongation Zone ◽

Cell Wall Extensibility ◽

Cell Wall Loosening ◽

Dependent Cell ◽

Wall Loosening ◽

Wall Extensibility

AbstractPlant salt tolerance is closely associated with a high rate of root growth. Although root growth is governed by cell-wall and apoplastic pH, the relationship between these factors in the root elongation zone under salinity stress remains unclear. Here, we assess apoplastic pH, pH- and expansin-dependent cell-wall extensibility, and expansin expression in the root elongation zone of salt-sensitive (Yongliang-15) and -tolerant (JS-7) cultivars under salinity stress. A six-day 80 mM NaCl treatment significantly reduced apical-root apoplastic pH, from 6.2 to 5.3, in both cultivars. Using a pH-dependent cell-wall extensibility experiment, we found that, under 0 mM NaCl treatment, the optimal pH for cell-wall loosening was 6.0 in the salinity-tolerant cultivar and 4.6 in the salinity-sensitive cultivar. Under 80 mM treatment, a pH of 5.0 mitigated the cell-wall stiffness caused by salinity stress in the salinity-tolerant cultivar, but promoted cell-wall stiffening in the salinity-sensitive cultivar. These changes in pH-dependent cell-wall extensibility are consistent with differences in the root growth of two cultivars under salinity stress. Exogenous expansin application, and expansin expression experiments, we found that salinity stress altered expansin expression, differentially affecting cell-wall extensibility under pH 5.0 and 6.0. TaEXPA7 and TaEXPA8 induced cell-wall loosening at pH 5.0, whereas TaEXPA5 induced cell-wall loosening at pH 6.0. These results elucidate the relationship between expansin and cell-wall extensibility in the root elongation zone, with important implications for enhancing plant growth under salinity stress.

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Arabidopsis HB52 mediates the crosstalk between ethylene and auxin signaling pathways by regulating PIN2, WAG1, and WAG2 during primary root elongation

10.1101/246017 ◽

2018 ◽

Author(s):

Zi-Qing Miao ◽

Ping-Xia Zhao ◽

Jie-Li Mao ◽

Lin-Hui Yu ◽

Yang Yuan ◽

...

Keyword(s):

Root Growth ◽

Signaling Pathways ◽

Molecular Mechanism ◽

Root Elongation ◽

Auxin Transport ◽

Primary Root ◽

Auxin Signaling ◽

Elongation Zone ◽

Ethylene Signaling ◽

Physiological Processes

AbstractThe gaseous hormone ethylene participates in many physiological processes of plants. It is well known that ethylene-inhibited root elongation involves basipetal auxin delivery requiring PIN2. However, the molecular mechanism how ethylene regulates PIN2 is not well understood. Here, we report that the ethylene-responsive HD-Zip gene HB52 is involved in ethylene-mediated inhibition of primary root elongation. Using biochemical and genetic analyses, we demonstrated that HB52 is ethylene-responsive and acts immediately downstream of EIN3. HB52 knock-down mutants are insensitive to ethylene in primary root elongation while the overexpression lines have dramatically shortened roots like ethylene treated plants. Moreover, HB52 upregulates PIN2, WAG1, and WAG2 by directly binding to their promoter, leading to an enhanced basipetal auxin delivery to the elongation zone and thus inhibiting root growth. Our work uncovers HB52 as an important crosstalk node between ethylene signaling and auxin transport in root elongation.

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FASCICLIN-LIKE 18 Is a New Player Regulating Root Elongation in Arabidopsis thaliana

Frontiers in Plant Science ◽

10.3389/fpls.2021.645286 ◽

2021 ◽

Vol 12 ◽

Author(s):

Hewot Allelign Ashagre ◽

David Zaltzman ◽

Anat Idan-Molakandov ◽

Hila Romano ◽

Oren Tzfadia ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Root Elongation ◽

Genetic Interaction ◽

Lateral Roots ◽

Primary Root ◽

Arabinogalactan Protein ◽

Wild Type ◽

Synthesis Inhibitor ◽

High Sucrose

The plasticity of root development represents a key trait that enables plants to adapt to diverse environmental cues. The pattern of cell wall deposition, alongside other parameters, affects the extent, and direction of root growth. In this study, we report that FASCICLIN-LIKE ARABINOGALACTAN PROTEIN 18 (FLA18) plays a role during root elongation in Arabidopsis thaliana. Using root-specific co-expression analysis, we identified FLA18 to be co-expressed with a sub-set of genes required for root elongation. FLA18 encodes for a putative extra-cellular arabinogalactan protein from the FLA-gene family. Two independent T-DNA insertion lines, named fla18-1 and fla18-2, display short and swollen lateral roots (LRs) when grown on sensitizing condition of high-sucrose containing medium. Unlike fla4/salt overly sensitive 5 (sos5), previously shown to display short and swollen primary root (PR) and LRs under these conditions, the PR of the fla18 mutants is slightly longer compared to the wild-type. Overexpression of the FLA18 CDS complemented the fla18 root phenotype. Genetic interaction between either of the fla18 alleles and sos5 reveals a more severe perturbation of anisotropic growth in both PR and LRs, as compared to the single mutants and the wild-type under restrictive conditions of high sucrose or high-salt containing medium. Additionally, under salt-stress conditions, fla18sos5 had a small, chlorotic shoot phenotype, that was not observed in any of the single mutants or the wild type. As previously shown for sos5, the fla18-1 and fla18-1sos5 root-elongation phenotype is suppressed by abscisic acid (ABA) and display hypersensitivity to the ABA synthesis inhibitor, Fluridon. Last, similar to other cell wall mutants, fla18 root elongation is hypersensitive to the cellulose synthase inhibitor, Isoxaben. Altogether, the presented data assign a new role for FLA18 in the regulation of root elongation. Future studies of the unique vs. redundant roles of FLA proteins during root elongation is anticipated to shed a new light on the regulation of root architecture during plant adaptation to different growth conditions.

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