Arabinose biosynthesis is critical for salt stress tolerance in Arabidopsis

Abstract

Summary The capability to maintain cell wall integrity is critical for plants to adapt to unfavourable conditions. l‐Arabinose (Ara) is a constituent of several cell wall polysaccharides and many cell wall‐localised glycoproteins, but so far the contribution of Ara metabolism to abiotic stress tolerance is still poorly understood. Here, we report that mutations in the MUR4 (also known as HSR8) gene, which is required for the biosynthesis of UDP‐Arap in Arabidopsis, led to reduced root elongation under high concentrations of NaCl, KCl, NaNO3, or KNO3. The short root phenotype of the mur4/hsr8 mutants under high salinity is rescued by exogenous Ara or gum arabic, a commercial product of arabinogalactan proteins (AGPs) from Acacia senegal. Mutation of the MUR4 gene led to abnormal cell−cell adhesion under salt stress. MUR4 forms either a homodimer or heterodimers with its isoforms. Analysis of the higher order mutants of MUR4 with its three paralogues, MURL, DUR, MEE25, reveals that the paralogues of MUR4 also contribute to the biosynthesis of UDP‐Ara and are critical for root elongation. Taken together, our work revealed the importance of the Ara metabolism in salt stress tolerance and also provides new insights into the enzymes involved in the UDP‐Ara biosynthesis in plants.

Comprehensive transcriptional analysis reveals salt stress-regulated key pathways, hub genes and time-specific response categories in common bermudagrass (Cynodon dactylon (L.) Pers.) roots

“…Mutation in MUR4 affects cell wall integrity and leads to reduced root elongation and defective cell-cell adhesion under high salinity [62]. Moreover, several AGPs (arabinogalactan proteins) encoding genes were found up-regulated by salt at the transcript level in our study (Fig.4f).…”

A wall with integrity: surveillance and maintenance of the plant cell wall under stress

“…Recent data from Arabidopsis mur4 mutants, which are deficient in arabinose synthesis, suggest that maintenance of CWI under high salinity requires arabinose-containing wall polymers (Zhao et al, 2019). Recent data from Arabidopsis mur4 mutants, which are deficient in arabinose synthesis, suggest that maintenance of CWI under high salinity requires arabinose-containing wall polymers (Zhao et al, 2019).…”

“…Another territory that remains largely unexplored is the synthesis of hemicelluloses, pectins and wall structural proteins during or after the growth recovery phase, and whether deposition of these wall matrix polymers is involved in maintaining CWI under salt stress. Recent data from Arabidopsis mur4 mutants, which are deficient in arabinose synthesis, suggest that maintenance of CWI under high salinity requires arabinose-containing wall polymers (Zhao et al, 2019).…”

Integrative Transcriptomic and Proteomic Analyses of Molecular Mechanism Responding to Salt Stress during Seed Germination in Hulless Barley

“…The cell wall is important for protecting plants from biotic stress, and its critical role in abiotic stress is widely discussed [18,31]. The UDP-glucose 4-epimerase (UGE) plays an important role in galactose metabolism and the biosynthesis of galactose-containing polysaccharides and can also participate in arabinose metabolism, affecting cell wall resistance [41,42]. The barley HvUGE1 gene is orthologous to AtUGE4 and also necessary to control carbohydrate partitioning in the cell wall [43].…”