Transcriptome Profiles of during the Early Infection of Resistant and Susceptible Maize Isogenic Lines.

The biotrophic fungus causes destructive head smut disease in maize ( L.). To explore the pathogenicity arsenal of this fungus, we tracked its transcriptome changes during infection of the maize seedling mesocotyls of two near-isogenic lines, HZ4 and HZ4R, differing solely in the disease resistance gene . Parasitic growth of resulted in thousands of differentially expressed genes (DEGs) compared with growth in axenic culture. The protein synthesis and energy metabolism of were predominantly enriched with down-regulated DEGs, consistent with the arrested hyphal growth observed following colonization. Nutrition-related metabolic processes were enriched with both up- and down-regulated DEGs, which, together with activated transmembrane transport, reflected a potential transition in nutrition uptake of once it invaded maize. Notably, genes encoding secreted proteins of were mostly up-regulated during biotrophy. -mediated resistance to head smut disease reduced the number of DEGs of , particularly those related to the secretome. These observations deepen our understanding of the mechanisms underlying pathogenicity and -induced innate immunity.