Foliar trichome- and aquaporin-aided water uptake in a drought-resistant epiphyte Tillandsia ionantha Planchon

Abstract

The atmospheric epiphyte Tillandsia ionantha is capable of surviving drought stress for 6 months or more without any exogenous water supply via an as of yet to be determined mechanism. When plants were soaked in water for 3 h, leaves absorbed a remarkably large amount of water (30-40% on the basis of fresh weight), exhibiting a bimodal absorption pattern. Radiolabeled water was taken up by the leaves by capillary action of the epidermal trichomes within 1 min (phase 1) and then transported intracellularly to leaf tissues over 3 h (phase 2). The removal of epidermal trichome wings from leaves as well as rinsing leaves with water significantly lowered the extracellular accumulation of water on leaf surfaces. The intracellular transport of water was inhibited by mercuric chloride, implicating the involvement of a water channel aquaporin in second-phase water absorption. Four cDNA clones (TiPIP1a, TiPIP1b, TiPIP1c, and TiPIP2a) homologous to PIP family aquaporins were isolated from the leaves, and RT-PCR showed that soaking plants in water stimulated the expression of TiPIP2a mRNA, suggesting the reinforcement in ability to rapidly absorb a large amount of water. The expression of TiPIP2a complementary RNA in Xenopus oocytes enhanced permeability, and treatment with inhibitors suggested that the water channel activity of TiPIP2a protein was regulated by phosphorylation. Thus, the high water uptake capability of T. ionantha leaves surviving drought is attributable to a bimodal trichome- and aquaporin-aided water uptake system based on rapid physical collection of water and subsequent, sustained chemical absorption.

Strategies of leaf water uptake based on anatomical traits

“…; Schönherr ; Ohrui et al . ) and ectodesms (Schönherr ), which can facilitate the formation of a continuous apoplastic pathway from the outside to the mesophyll, functioning in water absorption (Wahid ).…”

Drought and extreme temperature tolerance for <em>Tillandsia dasyliriifolia</em>, an epiphytic bromeliad from the northern coastal dune scrubland in Yucatan, Mexico

“…Furthermore, a dense layer of trichomes have the inverse effect in water loss; they help regulate leaf temperature and transpiration through increased light reflectance (Ehleringer, 1984; Ohrui et al, 2007). Low stomatal density and crassulacean acid metabolism (CAM, Martin, 1994;Ricalde et al, 2010) are other adaptations of Tillandsia dasyliriifolia to arid environments to avoid desiccation.…”

“…The atmospheric epiphyte Tillandsia ionantha Planch. after 6 months of drought was still green and maintained a constant level of osmotic and water potential and a positive carbon dioxide uptake (Ohrui et al, 2007).…”

Does Sourgrass leaf anatomy influence glyphosate resistance?

“…The presence of trichomes and aquaporins were essential in the absorption of water in Tillandsia ionantha plants (Ohrui et al, 2007;Maurel, 2001). Also the presence of trichomes facilitates the absorption of water and its influx in the mesophyll of leaves (Grammatikopoulos& Manetas, 1994).…”