Mitogen-Activated Protein Kinase CaDIMK1 Functions as a Positive Regulator of Drought Stress Response and Abscisic Acid Signaling in Capsicum annuum

Abstract

Protein phosphorylation by kinase is an important mechanism for adapting to drought stress conditions. Here, we isolated the <i>CaDIMK1</i> (<i>Capsicum annuum drought-induced MAP kinase 1</i>) from dehydrated pepper leaf tissue and functionally characterized it. Subcellular localization analysis revealed that the CaDIMK1 protein was localized in the cytoplasm and nucleus. <i>CaDIMK1</i>-silenced pepper plants exhibited drought-susceptible phenotypes that were characterized by increased transpiration rates, low leaf temperatures, and decreased stomatal closure. In contrast, <i>CaDIMK1</i>-overexpressing (OX) transgenic <i>Arabidopsis</i> plants were hypersensitive to abscisic acid (ABA) from germination to adult growth stages. Furthermore, the <i>CaDIMK1</i>-OX plants were tolerant to drought stress. The transcript levels of several stress-related genes were high in <i>CaDIMK1</i>-OX plants than in wild-type plants. Taken together, our data demonstrate that <i>CaDIMK1</i> acts as a positive modulator of drought tolerance and ABA signal transduction in pepper plants.