ORIGINAL ARTICLE

Cell Research (2006)16:599-608
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Water relations and an expression analysis of plasma membrane intrinsic proteins in sensitive and tolerant rice during chilling and recovery

Xin Yu, Yan Hui Peng, Min Hua Zhang, Yan Jun Shao, Wei Ai Su,Zhang Cheng Tang

¹Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China; ²Life Science College, Hebei Agriculture University, 38 Ling-Yu-Si street, Baoding, Hebei, 071001, China

Correspondence: Wei Ai Su Tel: 86-21-54924245; Fax: 86-21-54924015; E-mail: zstressc@online.sh.cn Received 1 Sep 2005; revised 25 Oct 2005; accepted 26 Dec 2005; published online 15 Jun 2006

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A symptom of chilling injury is development of water deficit in shoots, resulting from an imbalance of water transport and transpiration. In this work, two rice varieties (Oryza sativa L. var. Wasetoitsu and Somewake) seedlings were chilled at 7 °C, followed by recovery at 28 °C. Based on the growth phenotype and electrolyte leakage tests, Somewake was shown to be a chilling-tolerant variety, and Wasetoitsu a chilling-sensitive one. The chilling stress reduced markedly the relative water content (RWC) of leaves, accumulative transpiration and osmotic root hydraulic conductivity (Lp) in both varieties. But when returned to 28 °C, the water relation balance of Somewake recovered better. The mRNA expression profile of all the 11 plasma membrane intrinsic proteins (PIPs), a subgroup of aquaporins, was subsequently determined by real-time reverse transcription (RT)-PCR with TaqMan-minor grove binder (MGB) probes derived from rice var. Nipponbare during chilling treatment and recovery. Most of the PIP genes was down-regulated at the low temperature, and recovered at the warm temperature. The relative expression of some PIPs in both Somewake and Wasetoitsu decreased in parallel during the chilling. However during the recovery, the relative expression of OsPIP1;1, OsPIP2;1, OsPIP2;7 in shoots and OsPIP1;1, OsPIP2;1 in roots were significantly higher in Somewake than Wasetoitsu. This supports the role of PIPs in re-establishing water balance after chilling conditions. We discuss the diversified roles played by members of the aquaporin PIP subfamily in plant chilling tolerance depending on aquaporin isoforms, plant tissue and the stage of chilling duration.

Cell Research (2006) 16:599-608. doi:10.1038/sj.cr.7310077; published online 15 June 2006

Keywords: aquaporin, chilling, gene expression, plasma membrane intrinsic protein, rice