Expression profile analysis of maize in response to Setosphaeria turcica

Northern corn leaf blight (NCLB), caused by the hemibiotrophic fungal pathogen Setosphaeria turcica, is one of the major foliar diseases of maize. The use of resistant cultivars is the most effective, economical, and environmentally friendly means to control NCLB. At present, the molecular mechanisms of maize resistance to S. turcica is not clear. Elucidating the molecular resistance mechanisms of maize response to S. turcica would aid breeding for a maize variety with fungal tolerance. In this study, maize leaves before and after infection with S. turcica were sequenced by RNA-seq, and 5903 differentially expressed genes (DEGs) were screened. Among them, 950 and 2245 genes were up-regulated 12 h and 60 h (samples H12 and H60, respectively) after infection, 752 and 1956 genes were down-regulated in H12 and H60, respectively. The GO and KEGG enrichment analysis of the DEGs showed that the GO and Pathway with the most annotation sequences were closely related to plant resistance. The expression of eight randomly selected DEGs was analyzed using qRT-PCR, and expression was consistent with the RNA-seq data. The expression patterns of four categories of genes were analyzed namely, genes involved in plant and pathogen interactions, transcription factors related to plant stress-tolerance, genes related to plant hormones and plant antioxidant. Many resistant signaling pathways were initiated such as the MAPK signal transduction pathway and the expression of multiple antioxidant-related genes [Peroxidase (POD), Catalase (CAT), Glutathione-S-transferase (GST) and Superoxide Dismutase (SOD)] following S. turcica infection. Many disease resistance signal transduction pathways and defense response pathways were induced following maize infection by S. turcica, suggesting a multiple gene network system. To the best of our knowledge, this is the first time that RNA-seq technology has been used to perform transcription analysis of maize in response to S. turcica stress. Taken together, these data provide novel and valuable information that will help understand the resistance mechanism in maize against S. turcica and locate candidate genes related to maize resistance against S. turcica.