Differential expression of MEKK subfamily genes in Capsicum annuum L. in response to abscisic acid and drought stress

Abstract

Mitogen-activated protein kinase kinase kinases (MAPKKKs or MEKKs) are crucial components of the MAPK signaling cascades, which play central roles in the signaling transduction pathways for plant growth, development, and response to abiotic stresses such as drought. The MAPKKK gene families in pepper have not been functionally characterized yet. Here, from the pepper genome, we predicted 27 putative MAPKKK genes belonging to the MEKK subfamily (named CaMEKK1-27), based on in silico analysis. Phylogenetic analysis revealed that 14 CaMEKK genes were clustered into A5 of the five groups (A1-A5), of which 9 genes are primarily on chromosomes 2 and 7, and are located close to each other. These nine genes showed transcriptional regulation by treatment with abscisic acid (ABA) and drought stress in quantitative reverse-transcription PCR analysis. Among the ABA-and/or drought-induced CaMEKK genes, in a previous study, we isolated CaAIMK1 (Capsicum annuum ABA Induced MAP Kinase 1), which plays a positive role in drought resistance via an ABA-dependent pathway. Our expression analysis and functional characterization of the MEKK subfamily genes will provide a better understanding of the functional roles of pepper MAPK cascades in ABA-mediated drought responses.

CaADIP1‐dependent CaADIK1‐kinase activation is required for abscisic acid signalling and drought stress response in Capsicum annuum

“…Li et al, 2017). In pepper plants, the functions of MAPK cascades are related to ABA signalling and abiotic stress (He et al, 2015;Jeong et al, 2020;Lim et al, 2020). In the present study, CaADIP1 interacted with and inhibited kinase activity of the pepper MEKK CaADIK1.…”

“…To identify protein kinase candidates that interact with pepper CaADIP1 (Lim & Lee, 2016), we performed a one‐by‐one yeast‐two‐hybrid assay with CaADIP1 and protein kinases. We selected a MAP3 kinase designated CaMEKK22 (Lim et al ., 2020); we named this protein CaADIK1 ( Capsicum annuum ADIP1 Interacting MAP3 Kinase 1). The C‐terminal region (264–341 amino acids) of CaADIK1 protein had autoactivity in yeast cells (Fig.…”

“…In particular, MAPK signalling cascades play important roles in biotic stress sensing (Bigeard et al ., 2015), abiotic stress response (Colcombet & Hirt, 2008; de Zelicourt et al ., 2016) and ABA signalling (H. Li et al ., 2017; K. Li et al ., 2017). In pepper plants, the functions of MAPK cascades are related to ABA signalling and abiotic stress (He et al ., 2015; Jeong et al ., 2020; Lim et al ., 2020). In the present study, CaADIP1 interacted with and inhibited kinase activity of the pepper MEKK CaADIK1.…”

Differential Functions of Pepper Stress-Associated Proteins in Response to Abiotic Stresses

“…First, we performed qRT-PCR using template cDNA obtained from plants that had been subjected to different stress treatments (low temperature, dehydration, ABA, and mannitol), and the primers listed in Supplementary Table 1. As a positive control for stress treatment, we used CaOSR1, which is homologous to Arabidopsis RD29B (Park et al, 2016;Lim et al, 2020). It is noteworthy that members of the aforementioned six groups tended to show differential responses to different stresses (Figure 2B).…”

“…Although the demand for peppers is increasing worldwide, their productivity can be limited to varying extents by adverse environmental conditions, such as dehydration, high salinity, and extreme temperatures. To solve this problem, numerous studies have focused on the defense mechanisms activated in response to such environmental stresses (Chen et al, 2014;Guo et al, 2014;Park et al, 2016;Lim et al, 2018aLim et al, , 2020Kang et al, 2020;Wu et al, 2020). In recent decades, numerous stress-related genes have been discovered in the pepper plants.…”