ABA signalling modulates the detection of the LM6 arabinan cell wall epitope at the surface of Arabidopsis thaliana seedling root apices

Abstract

Summary• The hormonal and physiological regulations underpinning the cell contexts of structural features of the heterogeneous cell wall pectic polysaccharide rhamnogalacturonan-I are far from being understood.• The effect of the modulation of abscisic acid (ABA) concentrations and sensitivity on the detection of the LM6 1,5-arabinan epitope at the surface of Arabidopsis thaliana seedling root apices was assessed by means of fluorescence imaging.• Treatment with 50 nM ABA resulted in an increase in the detection of the LM6 epitope at the root surface in the region of the meristem. An inhibitor of ABA biosynthesis and introduction of the ABA synthesis mutation aba3-2 resulted in reduced epitope detection. The same ABA application resulted in an increase in the number of epidermal root meristem cells and both this and LM6 epitope detection were specifically disrupted in the abi4 ABA-insensitive mutant. These two effects were uncoupled with the application of higher ABA concentrations, which resulted in a reduction in the number of epidermal root meristem cells but increased LM6 epitope detection.• This work demonstrates a role for ABI4-mediated ABA signalling in the modulation of pectic arabinan occurrence at the A. thaliana root meristem.

Influence of Phytohormones on Monosaccharide Composition of Polysaccharides from Wheat Suspension Culture

“…At the same time, cells under the effect of ABA retain high amount of xylans, xyloglucans, and some amount of glucuronoarabinoxylans, and pectins. These results are in accordance with data in literature about exogeniously applied ABA, which stimulates the accumulation of pectic arabinan, in root meristem of Arabadopsis [20]. Arabinans are known to play role in cell-to-cell adhesion [21], mechanical property of the cell wall [22], endo-arabinase activity [23].…”

Environmental Nitrate Stimulates Abscisic Acid Accumulation in Arabidopsis Root Tips by Releasing It from Inactive Stores

“…The outer cell layers of the roots displayed almost no immunoreactivity, indicating that ABA is localized within the central root tissues (Figure 1; Supplemental Figures 1 and 2). Addition of exogenous ABA increased the immunofluorescence ( Figure 1B; Supplemental Figure 1) and treatment with fluridone (FLU), an inhibitor of ABA biosynthesis (Bartels and Watson, 1978;Han et al, 2010;Talboys et al, 2011), significantly reduced the immunoreactivity of ABA in the growing root tip ( Figure 1C; Supplemental Figure 1G). Similarly, aba2-1 mutants, which are defective in ABA biosynthesis (Léon-Kloosterziel et al, 1996;Cheng et al, 2002), had almost undetectable levels of ABA immunofluorescence (Supplemental Figure 3).…”

“…These findings add a mechanistic dimension to our understanding of NO 3 2 signaling and to the role of ABA in mediating environmental responses. ABA is required for meristem maintenance in Arabidopsis and thus exerts a positive effect on root growth in addition to the inhibitory effect seen with exogenous ABA treatment Talboys et al, 2011). Perhaps nitrate-induced ABA release confers a more fine-tuned regulation of ABA accumulation, due to slow, intracellular release.…”

Epitope detection chromatography: a method to dissect the structural heterogeneity and inter‐connections of plant cell‐wall matrix glycans

“…It is of interest that, in the comparison of RG-I in stem, root and proliferating cells, there are similar profiles for the LM5 galactan epitope but the arabinan epitopes are more variable and dynamic. It is well established that arabinan structural features as exemplified by the LM6 and LM13 epitopes are highly dynamic, and they may also be responsive to physiological signals (Verhertbruggen et al, 2009b;Talboys et al, 2011). The EDC profiles may indicate proportions of arabinan structural features that are associated with HG or other acidic polymers.…”