Abstract
Adaptation to drought stress is essential for plant growth and development. Plants often adapt to water deficit conditions by activating the ABA signaling. Here, we report that the pepper CaDIK1 (Capsicum annuum Drought Induced Kinase 1) gene is essential for plant tolerance to drought stress. CaDIK1 contains a serine-threonine kinase domain, which plays a role for attachment of phosphate to the target protein. The expression levels of CaDIK1 are upregulated in pepper leaves by ABA, drought, NaCl and H2O2 treatments suggesting its role in abiotic stress response. We used CaDIK1-silenced pepper and CaDIK1-overexpressing (OX) transgenic Arabidopsis plants to evaluate their responses to ABA and drought. CaDIK1-silenced pepper plants conferred a reduced ABA sensitivity and drought hypersensitivity, which was accompanied by high levels of transpirational water loss. CaDIK1-OX plants displayed opposite phenotypes to CaDIK1-silenced peppers. In contrast, substitution of Lys350 to Asn in the kinase domain of CaDIK1 did not lead to alteration of drought sensitivity. Collectively, these data indicate that CaDIK1 is a positive regulator of the ABA-mediated drought-stress tolerance.
Highlights
IntroductionPlants face different environmental stresses, such as drought, high salinity, and cold
As sessile organisms, plants face different environmental stresses, such as drought, high salinity, and cold
Its structure is similar to that of the AtLRK10L1.2 protein found in Arabidopsis and to the TaLRK10 protein found in wheat
Summary
Plants face different environmental stresses, such as drought, high salinity, and cold. Drought stress is major component of these stresses, which restricts growth and development causing mortal damage like cell destruction to plants and limits agricultural productivity. Plants modulate their physiological and molecular states by regulating gene expression, post translational modifications, and stomatal closure (Lee and Luan, 2012). When plants encounter drought stress, endogenous ABA is synthesized in several plant tissues and accumulated in leaves (Raghavendra et al, 2010) where it regulates the expression level of many stress response genes. The main response to increasing ABA levels is stomatal closure as it controls ion transport in guard cells (Geiger et al, 2009; Lee et al, 2009; Geiger et al, 2010). As a result, reduced transpirational water loss is enabling plants to tolerate drought stress
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