Abstract
Abiotic stresses restrict the growth and yield of crops. Plants have developed a number of regulatory mechanisms to respond to these stresses. WRKY transcription factors (TFs) are plant-specific transcription factors that play essential roles in multiple plant processes, including abiotic stress response. At present, little information regarding drought-related WRKY genes in maize is available. In this study, we identified a WRKY transcription factor gene from maize, named ZmWRKY40. ZmWRKY40 is a member of WRKY group II, localized in the nucleus of mesophyll protoplasts. Several stress-related transcriptional regulatory elements existed in the promoter region of ZmWRKY40. ZmWRKY40 was induced by drought, high salinity, high temperature, and abscisic acid (ABA). ZmWRKY40 could rapidly respond to drought with peak levels (more than 10-fold) at 1 h after treatment. Overexpression of ZmWRKY40 improved drought tolerance in transgenic Arabidopsis by regulating stress-related genes, and the reactive oxygen species (ROS) content in transgenic lines was reduced by enhancing the activities of peroxide dismutase (POD) and catalase (CAT) under drought stress. According to the results, the present study may provide a candidate gene involved in the drought stress response and a theoretical basis to understand the mechanisms of ZmWRKY40 in response to abiotic stresses in maize.
Highlights
IntroductionTraditional crop breeding methods cannot meet the production demands of fine varieties with stress tolerance
Environmental stresses seriously affect plant growth and crop productivity
Gene ontology (GO) analyses were used to classify the differentially expressed genes (DEGs) into functional groups, and the DEGs were analyzed against the KEGG database to further understand which pathways the DEGs may be involved in (Supplementary Figure S1B,C)
Summary
Traditional crop breeding methods cannot meet the production demands of fine varieties with stress tolerance. As one of the largest TFs families in plants, WRKYs are characterized by their conservative WRKY domains that can recognize the W-box element in the promoter of its target genes, and play an important role in gene transcription and regulation [7]. Depending on their structural features, the WRKYs can be divided into three basic groups: group I (contains two WRKY domains), group II and III (contain only one WRKY domain) [7]. The zinc finger motif in the WRKY domain (C-X4-5-C-X22-23-H-X1-H or C-X7-C-X23-H-Xe-C, respectively) is different between groups II and III [8]
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