Tanaka H, Osakabe Y, Katsura S, Mizuno S, Maruyama K, Kusakabe K, Mizoi J, Shinozaki K, Yamaguchi-Shinozaki K

Membrane-anchored receptor-like protein kinases (RLKs) recognize extracellular signals at the cell surface and activate the downstream signaling pathway by phosphorylating specific target proteins. We analyzed a receptor-like cytosolic kinase (RLCK), ARCK1, whose expression was induced by abiotic stress. ARCK1 belongs to the cysteine-rich repeat (CRR)-RLK subfamily and encodes a cytosolic ...

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protein kinase. The arck1 mutant showed higher sensitivity than the wild-type to ABA and osmotic stress during the postgerminative growth phase. CRK36, an abiotic stress-inducible RLK belonging to the CRR-RLK subfamily, was screened as an interacting factor with ARCK1 by co-expression analyses and a yeast two-hybrid system. CRK36 physically interacted with ARCK1 in plant cells and the kinase domain of CRK36 phosphorylated ARCK1 in vitro. We generated CRK36 RNAi transgenic plants and the transgenic plants with suppressed CRK36 expression showed higher sensitivity than arck1-2 to ABA and osmotic stress during the postgerminative growth phase. Microarray analysis using CRK36 RNAi plants revealed that the suppression of CRK36 up-regulates several ABA-responsive genes, such as LEAs, oleosin, ABI4, and ABI5. These results suggest that CRK36 and ARCK1 form a complex and negatively control ABA and osmotic stress signal transduction. © 2012 The Authors. The Plant Journal© 2012 Blackwell Publishing Ltd.

Date: Jan. 07, 2012

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