ZmWRKY17 negatively regulates salt tolerance through ABA signaling pathway in maize

Maize (Zea mays L.) is an important cereal crop worldwide, but production is constrained by salt stress, which disrupts plant cell nutrient metabolism, leading to diminished growth and yield. Therefore, the mining of salt-tolerance genes and breeding of new salt-tolerant germplasm is crucial for improvement of maize yield. In this study, ZmWRKY17 (Zm00001d004086) overexpression and mutant lines were exposed to 250-mM and 300-mM NaCl, respectively, for 7 days. Exposed to salt stress, the overexpression lines produced significantly more malondialdehyde and hydrogen peroxide than the control line, accompanied by an increased rate of superoxide anion production and relative electrolyte leakage. The mutant line had a higher percentage survival, higher leaf relative water content, and lower cellular damage under extreme salt stress. According to these findings, ZmWRKY17 appears to have a negative regulatory effect on maize salt tolerance. In addition, under salt stress, ZmWRKY17 overexpression plants accumulated more abscisic acid (ABA) than the control plants. The root of ZmWRKY17 overexpression plants showed reduced sensitivity to ABA. Based on the results of transcriptome analysis, two candidate genes, Zm00001d016105 (ZmPYL10) and Zm00001d016294 (ZmPYL3), were screened for regulation by ZmWRKY17. The dual-luciferase experiments demonstrated that ZmWRKY17 binds to the promoter regions of ZmPYL10 and ZmPYL3, thereby regulating the expression of downstream genes. In conclusion, this study indicates that ZmWRKY17 is involved in regulating the expression of ABA receptor genes ZmPYL10 and ZmPYL3 to reduce the sensitivity of plants to ABA and, ultimately, negatively regulate plant salt tolerance.