Journal Article

Aquaporin Isoforms Responsive to Salt and Water Stresses and Phytohormones in Radish Seedlings

Shinobu Suga, Setsuko Komatsu and Masayoshi Maeshima

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 10, pages 1229-1237
Published in print October 2002 | ISSN: 0032-0781
Published online October 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf148
Aquaporin Isoforms Responsive to Salt and Water Stresses and Phytohormones in Radish Seedlings

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  • Biochemistry
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Aquaporins in the plasma and vacuolar membranes play a key role in the intercellular and intracellular water transport in plants. First, we quantitated the absolute amounts for mRNAs of eight aquaporin isoforms in hypocotyls of radish seedlings. Then, we investigated the effects of salt and water stresses (150 mM NaCl, 300 mM mannitol and 20% polyethylene glycol) and phytohormones (gibberellic acid, abscisic acid and brassinolide) on the mRNA and protein levels of aquaporins in the plasma membrane (RsPIP1-1, 1–2, 1–3, 2–1, 2–2 and 2–3) and vacuolar membrane (RsTIP1-1 and 2–1). The mRNA and protein levels of RsTIP1-1, RsTIP2-1, RsPIP1-1, RsPIP1-2 and RsPIP1-3 were comparatively constant. In contrast, mannitol treatment altered the mRNA levels of RsPIP2-1, RsPIP2-2 and RsPIP2-3 in roots. Immunoblot analysis showed that the RsPIP2-1 protein level was increased by NaCl treatment and decreased by treatment with mannitol and polyethylene glycol. Gibberellic acid and abscisic acid suppressed the levels of mRNAs of RsPIP2-1, RsPIP2-2 and RsPIP2-3 and the protein level of RsPIP2-1 in roots. On the other hand, the protein levels of RsPIP1-group members and RsTIPs were scarcely changed by these phytohormones. In the case of hypocotyls and cotyledons, the mRNA and protein levels of eight isoforms were not markedly affected by any treatment. These results indicate that aquaporins in the root, especially the RsPIP2 group, may be a stress responsive type of aquaporin at least in the protein level.

Keywords: Keywords: Aquaporin – Phytohormone — Plasma membrane — Salt stress — Water channel.; Abbreviations: ABA, abscisic acid; BL, brassinolide; GA3, gibberellic acid; PEG, polyethylene glycol; RsPIP, radish plasma membrane aquaporin; RsTIP, radish vacuolar membrane aquaporin.

Journal Article.  5456 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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