Genome-wide identification of the GST reveals ZmGST1 enhances the resistance to Exserohilum turcicum in maize

Northern corn leaf blight is caused by Exserohilum turcicum and poses a significant threat to maize yields. Therefore, it is of vital importance to explore disease-resistant genes and cultivate disease-resistant varieties. Glutathione S -transferases (GSTs) play an important role in plant defense reactions. We previously found that GST genes are significantly regulated in maize after infection with E. turcicum in a comparative RNA-seq transcriptome study, however, the function of GSTs in resisting NCLB remains unclear. In this study, 31 ZmGST genes were identified in the maize genome and were classified into the tau, phi, and zeta classes based on phylogenetic analysis. Analysis of the exon-intron structure of the ZmGST genes revealed that the number of exons ranged from 1 to 9. Promoter analysis identified 965 cis-elements associated with development-related elements, environmental stress-related components, hormone-related elements and light-responsive elements. Through a comparative RNA-seq transcriptome analysis, the expression of ZmGST1 is significantly up-regulated in the resistant maize inbred line upon E. turcicum infection compared with the susceptible maize inbred line. The full-length ZmGST1 (699 bp) was found to possess conserved GST_N and GST_C domains characteristics. The overexpression of ZmGST1 in maize enhances the resistance to E. turcicum by increasing antioxidant enzyme activities (SOD, POD, GST), reducing H 2 O 2 content and upregulating pathogenesis-related genes ( PR1 , PR5 , PR10.1 / 10.2 ). While, the EMS mutant plant showed the opposite results. We characterized 31 GST genes in maize and found that ZmGST1 is significantly induced in the resistant maize inbred line compared with the susceptible maize inbred line. Moreover, ZmGST1 can positively regulate maize resistance to E. turcicum infection through enhancing antioxidant enzyme activities and PR gene expression levels. These results uncovered that ZmGST1 is a key gene in maize defense against NCLB and provide new insights for molecular breeding of resistant varieties.