Journal Article

Effect of Low Root Temperature on Hydraulic Conductivity of Rice Plants and the Possible Role of Aquaporins

Mari Murai-Hatano, Tsuneo Kuwagata, Junko Sakurai, Hiroshi Nonami, Arifa Ahamed, Kiyoshi Nagasuga, Toshinori Matsunami, Keiko Fukushi, Masayoshi Maeshima and Masumi Okada

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 9, pages 1294-1305
Published in print September 2008 | ISSN: 0032-0781
Published online August 2008 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcn104
Effect of Low Root Temperature on Hydraulic Conductivity of Rice Plants and the Possible Role of Aquaporins

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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The role of root temperature TR in regulating the water-uptake capability of rice roots and the possible relationship with aquaporins were investigated. The root hydraulic conductivity Lpr decreased with decreasing TR in a measured temperature range between 10°C and 35°C. A single break point (TRC = 15°C) was detected in the Arrhenius plot for steady-state Lpr. The temperature dependency of Lpr represented by activation energy was low (28 kJ mol–1) above TRC, but the value is slightly higher than that for the water viscosity. Addition of an aquaporin inhibitor, HgCl2, into root medium reduced osmotic exudation by 97% at 25°C, signifying that aquaporins play a major role in regulating water uptake. Below TRC, Lpr declined precipitously with decreasing TR (Ea = 204 kJ mol–1). When TR is higher than TRC, the transient time for reaching the steady-state of Lpr after the immediate change in TR (from 25°C) was estimated as 10 min, while it was prolonged up to 2–3 h when TR < TRC. The Lpr was completely recovered to the initial levels when TR was returned back to 25°C. Immunoblot analysis using specific antibodies for the major aquaporin members of PIPs and TIPs in rice roots revealed that there were no significant changes in the abundance of aquaporins during 5 h of low temperature treatment. Considering this result and the significant inhibition of water-uptake by the aquaporin inhibitor, we hypothesize that the decrease in Lpr when TR < TRC was regulated by the activity of aquaporins rather than their abundance.

Keywords: Aquaporin; Hydraulic conductivity; Rice; Root temperature

Journal Article.  7356 words.  Illustrated.

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

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