Leaf biomechanical properties in Arabidopsis thaliana polysaccharide mutants affect drought survival

Abstract

Individual sugars are the building blocks of cell wall polysaccharides, which in turn comprise a plant׳s overall architectural structure. But which sugars play the most prominent role in maintaining a plant׳s mechanical stability during large cellular deformations induced by drought? We investigated the individual contributions of several genes that are involved in the synthesis of monosaccharides which are important for cell wall structure. We then measured drought tolerance and mechanical integrity during simulated drought in Arabidopsis thaliana. To assess mechanical properties, we designed a small-scale tensile tester for measuring failure strain, ultimate tensile stress, work to failure, toughness, and elastic modulus of 6-week-old leaves in both hydrated and drought-simulated states. Col-0 mutants used in this study include those deficient in lignin, cellulose, components of hemicellulose such as xylose and fucose, the pectic components arabinose and rhamnose, as well as mutants with enhanced arabinose and total pectin content. We found that drought tolerance is correlated to the mechanical and architectural stability of leaves as they experience dehydration. Of the mutants, S096418 with mutations for reduced xylose and galactose was the least drought tolerant, while the arabinose-altered CS8578 mutants were the least affected by water loss. There were also notable correlations between drought tolerance and mechanical properties in the diminished rhamnose mutant, CS8575 and the dehydrogenase-disrupted S120106. Our findings suggest that components of hemicellulose and pectins affect leaf biomechanical properties and may play an important role in the ability of this model system to survive drought.

Changes in elastic modulus, leaf tensity and leaf density during dehydration of detached leaves in two plant species of Moraceae

“…The stable cells elasticity was also conducive to the maintenance of intracellular water availability, which would sustain the stability of PSII and maintain the photosynthesis. Similar results were reported by Balsamo et al (2015).…”

Gene stacking of multiple traits for high yield of fermentable sugars in plant biomass

“…In these plants, we may have reached the critical point where accumulation of galactan impacts tissue properties and consequently stem mechanical properties. Indeed, galactose content in the cell wall has been demonstrated to impact mechanical properties of Arabidopsis leaves [ 29 ]. However, we cannot conclude from the data whether the decreased stiffness in the W4 and X4 lines is due only to the high galactan content or due to the combination of high galactan with low lignin mediated by QsuB expression.…”

A computational approach for inferring the cell wall properties that govern guard cell dynamics

“…The three cell wall mutants are irx8, pmr5 and pmr6. The irx8 mutant is deficient in the hemicellulose building block, xylose, and exhibited brittle behaviour under mechanical load (Balsamo et al, 2015). As xylose is related to CMF cross-linking, the model predicts that the stomata will function normally, and possibly have an increased aperture relative to the wild type (Rui and Anderson, 2016).…”