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

Ohrui, T; Nobira, H; Sakata, Y; Taji, T; Yamamoto, C; Nishida, K; Yamakawa, T; Sasuga, Y; Yaguchi, Y; Takenaga, H; Tanaka, Shigeo

Ohrui, T; Nobira, H; Sakata, Y; Taji, T; Yamamoto, C; Nishida, K; Yamakawa, T; Sasuga, Y; Yaguchi, Y; Takenaga, H; Tanaka, Shigeo.

Afiliación

Ohrui T; Faculty of Applied Bioscience, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Japan.

Planta ; 227(1): 47-56, 2007 Dec.

Article en En | MEDLINE | ID: mdl-17674031

RESUMEN

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.

Asunto(s)

Acuaporinas/fisiología; Desastres; Hojas de la Planta/fisiología; Tillandsia/fisiología; Agua/metabolismo; Secuencia de Aminoácidos; Animales; Acuaporinas/genética; Acuaporinas/metabolismo; Transporte Biológico/genética; Transporte Biológico/fisiología; Forma de la Célula/genética; Forma de la Célula/fisiología; Femenino; Regulación de la Expresión Génica de las Plantas; Genes de Plantas; Microinyecciones; Microscopía Electrónica de Rastreo; Datos de Secuencia Molecular; Oocitos/citología; Oocitos/metabolismo; Epidermis de la Planta/genética; Epidermis de la Planta/fisiología; Epidermis de la Planta/ultraestructura; Hojas de la Planta/genética; Hojas de la Planta/ultraestructura; Proteínas de Plantas/genética; Proteínas de Plantas/metabolismo; Proteínas de Plantas/fisiología; ARN Complementario/administración & dosificación; ARN Complementario/genética; Reacción en Cadena de la Polimerasa de Transcriptasa Inversa; Homología de Secuencia de Aminoácido; Tillandsia/genética; Tillandsia/ultraestructura; Xenopus

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Agua / Hojas de la Planta / Acuaporinas / Tillandsia / Desastres Idioma: En Revista: Planta Año: 2007 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Alemania

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