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

Pepper SnRK2.6‐activated MEKK protein CaMEKK23 is directly and indirectly modulated by clade A PP2Cs in response to drought stress

“…As full‐length CaSnRK2.6 has auto‐activity in yeast cells, we used a C‐terminal truncated CaSnRK2.6/SRK2E (amino acids 1–320: CaSnRK2.6 A320) as bait. Three CaMEKKs, namely, CaDIMK1 (Kim et al ., 2021), CaADIK1 (Jeong et al ., 2021), and CaMEKK23 (Lim et al ., 2020), were accordingly shown to interact with CaSnRK2.6 (Figs 1a, S1A), with in vitro pull‐down assays subsequently being performed to confirm the interactions. In line with expectations, we established that CaSnRK2.6 interacts with CaMEKK23 and CaDIMK1, although not with CaADIK1 (Figs 1b, S1B,C).…”

“…6). These phenotypic changes are also consistent with those observed previously following the silencing of CaDIMK1 (Kim et al ., 2021) and CaADIK1 (Jeong et al ., 2021), a paralog of CaMEKK23 . Similar to CaMEKK23, CaDIMK1 interacted with CaSnRK2.6 (Fig.…”

“…Previously, we have reported that pepper MEKK subfamily genes are differentially expressed in response to ABA and drought treatments (Lim et al ., 2020), among which, CaAIMK1, CaDIMK1, and CaADIK1 play positive roles in ABA signaling and the drought stress responses (Jeong et al ., 2020, 2021; Kim et al ., 2021). In this study, we identified CaMEKK23, which physically interacts with both pepper SnRK2.6 and group A PP2Cs, with CaMEKK23 phosphorylation being promoted by CaSnRK2.6 and inhibited by CaPP2Cs.…”

Genome-wide association analysis for drought tolerance and associated traits in faba bean (Vicia faba L.)

“…Finally, mitogen-activated protein kinase (MAPK) genes are involved in many cell activities including growth, differentiation and proliferation, as well as environmental stress responses. MAPKs activation is a common defense response of plants to a range of abiotic stressors ( Komis et al., 2018 ; Muhammad et al., 2019 ; Kim et al., 2021 ). Because drought stress leads simultaneously to osmotic and oxidative stress ( Zhu, 2002 ), osmotic stress activates several protein kinases including MAPKs, which mediate osmotic homeostasis and/or detoxification responses.…”

Pepper stress‐associated protein 14 is a substrate of CaSnRK2.6 that positively modulates abscisic acid‐dependent osmotic stress responses

“…For in vitro phosphorylation analyses, we used kinase buffer (1 mM CaCl 2 , 1 mM dithiothreitol, 2.5 mM MnCl 2 , 2.5 mM MgCl 2 , and 20 mM Tris-HCl, at pH 7.5) and 15 lCi [c-32 P]-ATP, with assays being performed using a previously described protocol (Jeong et al, 2020(Jeong et al, , 2021Kim et al, 2021).…”