Genomic profile of maize response to Aspergillus flavus infection

The opportunistic pathogen Aspergillus flavus infects important seed crops, including corn, peanuts, and cotton. A. flavus is capable of producing mycotoxins called aflatoxins. Aflatoxin 13, the major mycotoxin contaminant of maize, is a potent carcinogen and has been directly linked to hepatocellular carcinoma. Natural sources of maize fungal resistance exist, but efforts to increase resistance through traditional plant breeding have yielded little success. Using the maize Unigene 1-1.05 arrays, a comparison of resistant (Mp313E) and susceptible (Va35) inbred maize lines 48 hours post-A. flavus infection identified 236 genes as significant. During infection, 135 genes were up-regulated in the susceptible maize line Va35, 112 genes were up-regulated in the resistant maize line Mp313E, 12 genes were up-regulated in both lines, and 1 gene was down-regulated in both lines compared to uninfected lines. Comparisons of the biological profile responses of these maize lines revealed a striking difference in reaction to infection. These identified genes will serve as the initial step for developing molecular markers to understand this complex interaction and help with introgression of A. flavus resistance into maize hybrids.