Abstract
WRKY transcription factors constitute one of the largest transcription factor families in plants, and play crucial roles in plant growth and development, defense regulation and stress responses. However, knowledge about this family in maize is limited. In the present study, we identified a drought-induced WRKY gene, ZmWRKY106, based on the maize drought de novo transcriptome sequencing data. ZmWRKY106 was identified as part of the WRKYII group, and a phylogenetic tree analysis showed that ZmWRKY106 was closer to OsWRKY13. The subcellular localization of ZmWRKY106 was only observed in the nucleus. The promoter region of ZmWRKY106 included the C-repeat/dehydration responsive element (DRE), low-temperature responsive element (LTR), MBS, and TCA-elements, which possibly participate in drought, cold, and salicylic acid (SA) stress responses. The expression of ZmWRKY106 was induced significantly by drought, high temperature, and exogenous abscisic acid (ABA), but was weakly induced by salt. Overexpression of ZmWRKY106 improved the tolerance to drought and heat in transgenic Arabidopsis by regulating stress-related genes through the ABA-signaling pathway, and the reactive oxygen species (ROS) content in transgenic lines was reduced by enhancing the activities of superoxide dismutase (SOD), peroxide dismutase (POD), and catalase (CAT) under drought stress. This suggested that ZmWRKY106 was involved in multiple abiotic stress response pathways and acted as a positive factor under drought and heat stress.
Highlights
Changing environmental factors, such as abiotic stresses, influence plant growth and development [1]
We searched for ZmWRKYs among the differentially expressed genes (DEGs), and found 14 ZmWRKYs induced by drought treatment (Figure 1B)
We found that the expressions of abscisic acid (ABA)-related genes were higher in transgenic lines, which indicated that overexpression of ZmWRKY106 led to enhanced tolerance of drought stress through the ABA-dependent pathway (Figure 7D–F)
Summary
Changing environmental factors, such as abiotic stresses, influence plant growth and development [1]. Drought and heat stresses seriously threaten crop productivity and quality. It is important to explore the stress response mechanisms of plants and to enhance their tolerance to drought and heat to increase crop productivity without expanding cultivated land [2]. Environmental stresses initiate transcription factor (TF)-mediated expression of a variety of genes in plants, including bZIP, AP2/EREBP, MYB/MYC, NAC and WRKY [1,3,4,5,6]. It has been reported that WRKYs participated in defense responses by binding to the W-box located in the promoters of plant defense-related genes [9,10,11]. 13 rice WRKY genes have regulated resistance against pathogens [13,14,15,16,17]
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