Zou JJ, Wei FJ, Wang C, Wu JJ, Ratnasekera D, Liu WX, Wu WH

Plant calcium-dependent protein kinases (CDPKs) may function as calcium sensors and play important roles in regulation of plant growth and development and in plant responses to biotic and abiotic stresses. The Arabidopsis genome encodes 34 CDPKs and most of them have not been functionally characterized. Here we report the functional ...

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characterization of CPK10 in Arabidopsis response to drought stress. The cpk10 mutant, a T-DNA insertion mutant for Arabidopsis CPK10 gene, showed much more sensitive phenotype to drought stress compared with wild-type plants, while the CPK10 overexpression lines displayed enhanced tolerance to drought stress. Induction of stomatal closure and inhibition of stomatal opening by ABA and Ca(2+) were impaired in the cpk10 mutants. Using the yeast two-hybrid methods, a heat shock protein HSP1 was identified as a CPK10-interacting protein. The interaction between CPK10 and HSP1 was further confirmed by pull-down and bimolecular fluorescence complementation (BiFC) assays. The HSP1 knock-out mutant (hsp1) plants showed similar sensitive phenotype under drought stress as the cpk10 mutant plants, and were similarly less sensitive to ABA and Ca(2+) in regulation of stomatal movements. Electrophysiological experiments showed that ABA- and Ca(2+)-inhibition of the inward K(+) currents in stomatal guard cells were impaired in the cpk10 and hsp1 mutants. All presented data demonstrated that CPK10, possibly via interacting with HSP1, plays important roles in ABA and Ca(2+)-mediated regulation of stomatal movements.

Date: Aug. 30, 2010

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