Dehydration‐induced expression of a 31‐kDa dehydrin in Polypodium polypodioides (Polypodiaceae) may enable large, reversible deformation of cell walls

Abstract

Current and predicted climate changes caused by global warming compel greater understanding of the molecular mechanisms that plants use to survive drought. The desiccation-tolerant fern Polypodium polypodioides exhibits extensive cell wall folding when dried to less than 15% relative water content (RWC) and rapidly (within 24 h) rehydrates when exposed to water and high humidity. A 31-kDa putative dehydrin polypeptide expressed in partially and fully dry tissues detected via western blotting was present only during drying and rapidly dissipated (within 24 h) upon tissue rehydration. Immunostaining indicates the presence of dehydrin near the cell wall of partially and fully dried tissues. Atomic force microscopy of tracheal scalariform perforations indicates that dry vascular tissue does not undergo significant strain. Additionally, environmental scanning electron microscopy reveals differential hydrophilicity between the abaxial and adaxial leaf surfaces as well as large, reversible deformation. The ability to avoid cell wall damage in some desiccation-tolerant species may be partially attributed to cell wall localization of dehydrins enabling reversible, large cell-wall deformation. Thus, the de novo synthesis of dehydrin proteins and potential localization to the cell walls of these desiccation-tolerant species may play a role in avoiding mechanical failure during drought.

Reversible in vivo cellular changes occur during desiccation and recovery: Desiccation tolerance of the resurrection filmy fern Hymenophyllum dentatum Cav.

“…During desiccation, leaves and pinnae fold upward, since the adaxial side underwent negative strain to a greater extent than the abaxial side, resulting in the pinnae becoming highly concave (Layton et al 2010). Leaf folding has been reported in other resurrection plants such as the angiosperms Harberlea rhodopensis (Georgieva et al 2010), and Myrothamnus flabellifolius (Moore et al 2006) and the fern Polypodium polypodioides (Layton et al 2010), among others (Rascio & La Rocca 2005).…”

“…Resurrection plants use two different approaches to minimize this stress: 1) water replacement, where cells maintain their original volume and became packed with vacuoles filled with non-aqueous matter and 2) reduction in cellular volume by extensive cell wall folding, which should reduce tensions on structures enclosed by the wall (Willigen et al 2004). The mechanisms by which the cell walls of desiccation tolerant species manage to withstand the strain caused by massive loss of cellular water (and volume) and changes in mechanical properties of wet versus dry cell walls remain unresolved (Moore et al 2006, Layton et al 2010.…”

Interaction of aluminium and drought stress on root growth and crop yield on acid soils

“…The highly hydrophilic pectin can attract and sequester water and may behave as a lubricant between individual CW layers and thus avoid the CW collapse and damage from water loss. In addition, the hydrophilic protein dehydrin, which is supposed to be localized in the CW, may also play a role similar to pectin in preventing the CW from water deficit-caused mechanical fracture (Layton et al 2010), maintaining the elastic extension (reversible stretching) properties and, consequently, the porosity of the CW. Also, CW structural proteins such as the hydroxyproline-rich Yang et al (2010Yang et al ( , 2011c glycoprotein extensin, can cross-link with other polymers in the CW and thus affect CW porosity (Brett and Waldron 1996).…”

Plant Abiotic Stress: Insights from the Genomics Era

“…However, it has been possible, based on homology inferences, to define four broad categories of C. plantagineum genes induced by dehydration: protective proteins including such as hydrophilins, regulatory proteins and RNA, carbohydrate metabolism enzymes, and proteins involved in water transport (Bartels 2005). Other insights have come from naturally occurring desiccation tolerant plants, recently a 31-kDa putative dehydrin polypeptide was discovered in the desiccation-tolerant fern Polypodium polypodioide, found to be localized at the cell walls and present only during drying (Layton et al 2010). The protein rapidly dissipated upon tissue rehydration, along with changing the hydrophilicity of leaf surfaces and enabling reversible cell wall deformation.…”