Comparative transcriptome analysis highlights resistance regulatory networks of maize in response to Exserohilum turcicum infection at the early stage

Northern corn leaf blight, caused by Exserohilum turcicum (E. turcicum), is one of the most destructive diseases in maize, leading to serious yield losses. However, the underlying molecular mechanisms of E. turcicum infection response in maize remain unclear. In this study, we performed comparative transcriptome analysis in resistant maize inbred line J9D207 (R) and susceptible maize inbred line PH4CV (S) after infecting with E. turcicum at 0 h, 24 h and 72 h, respectively. Compared with 0 h, 9656 (24 h) and 8748 (72 h) differentially expressed genes (DEGs) were identified in J9D207, and 7915 (24 h) and 7865 (72 h) DEGs were identified in PH4CV. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that alpha-linolenic acid metabolism, benzoxazinoid biosynthesis, flavonoid biosynthesis and phenylpropanoid biosynthesis might be involved in maize defense reactions. Some DEGs coded for transcription factors, such as MYB-related, ERF, NAC, bZIP, bHLH and WRKY families, which indicated that they may participate in resistance against E. turcicum. In addition, DEGs involved in SA, JA, ABA and ET signaling pathways were revealed. Moreover, 75 SOD activity-related genes and 421 POD activity-related genes were identified through weighted gene co-expression network analysis (WGCNA), respectively. These results provide a novel insight into the resistance mechanism of maize in response to E. turcicum inoculation.