Maize ZmWRKY71 gene positively regulates drought tolerance through reactive oxygen species homeostasis

Abstract

Drought stress severely affects plant growth and yield. The plant-specific WRKY transcription factors play an important role in regulating the plant response to abiotic stresses. In this study, we identified a group I WRKY gene from maize, designated ZmWRKY71. Real-time quantitative reverse transcription-PCR analysis revealed that ZmWRKY71 was predominantly expressed in the roots and was induced by drought. ZmWRKY71 was localized in the nucleus and showed transcriptional activity in yeast. Heterologous overexpression of ZmWRKY71 improved drought tolerance in yeast and Arabidopsis. Compared with the wild type, the overexpression lines showed a higher survival rate under drought stress with reduced malondialdehyde content and elevated antioxidant enzyme activities. In contrast, mutation of ZmWRKY71 in maize leads to increased sensitivity to drought stress, reduced survival, elevated concentrations of reactive oxygen species, and increased malondialdehyde content. RNA-sequencing analysis revealed that the expression patterns of genes associated with translation, membrane, and oxidoreductase activity pathways were altered under drought stress. Yeast one-hybrid, dual-luciferase, and electrophoretic mobility shift assays confirmed that ZmWRKY71 was capable of directly binding to the W-box element in the promoter region of ZmPOD42 (Zm00001eb330550). Taken together, the results show that ZmWRKY71 positively regulates maize drought tolerance. This research enriches the drought tolerance gene pool for maize and provides a theoretical basis for maize drought tolerance breeding.

Keywords: Drought stress; ROS; Transcription factor; ZmWRKY71.