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Pak. J. Bot., 47(5): 1665-1670, 2015.

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SERINE/THREONINE PHOSPHATASE TAPP2Cs MIGHT BE SERVED AS AN EARLY SIGNAL MOLECULE FOR WATER STRESS IN WHEAT

K.H. SONG^1Ф, W.L. TIAN^1Ф, B.Z. HOU¹, X.R. MEI², Y.Z. LI^2*, J.X. GUO^1*

Abstract: Much progress has been made towards understanding the role of serine/threonine phosphatases type 2C (PP2Cs) in abscisic acid (ABA) signaling transduction. However, how the negative regulator, PP2Cs, responds to plant water loss remains unclear. Here, we used a series of relative soil moisture [RSM: 85% (well watered), 65% (moderate stress), 45% (severe stress)] potted winter wheat (Triticum aestivum L.) and the detached leaves to detect ABA levels and transcripts of PP2Cs, including PP2C40, PP2C45, PP2C59 and PP2C6 as well as the core downstream signals of ABA, including ABF, SnRK2.4 and SnRK2.5. The results showed that the continual loss of water led to a consistent increase in ABA levels, and that the mRNA expression levels of PP2Cs were dependent on plant water condition. PP2Cs expression could be induced by a slight loss of water, and inhibited under severe loss of water. These results were further confirmed by the transcripts of ABF, SnRK2.4 and SnRK2.5. Furthermore, in slight loss of water, 100 µM exogenous ABA could promote PP2Cs expression; in severe loss of water, it inhibited PP2Cs expression. In conclusion, ABA accumulation is controlled by water condition and the PP2C expression is dependent on plant water condition, suggesting that PP2Cs might be served as an early signal molecule for water stress in wheat.

Key words: Wheat, Abscisic acid (ABA), Type 2C protein phosphatase (PP2Cs), Water loss, Gene expression.

¹Beijing Key Laboratory of New technology in Agricultural Application, College of Plant Science and Technology, Beijing University of Agriculture, No.7 Beinong Road, Changping District, Beijing 102206, P. R. China

²Water Resources and Dryland Farming Laboratory, Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Haidian District, Beijing 100081, P. R. China

^*Correspondence author’s e-mail address: guojiaxuangjx@163.com, liyz-jie@163.com;

Tel/Tax: 86-10-80794426 ^ФAuthors contributed equally to this work