Comparative analysis of the performance of Aspergillus flavus on resistant and susceptible maize genotypes during infection

Several species of the genus Aspergillus are mycotoxigenic, producing carcinogenic aflatoxins in crops like peanuts and maize. Development of fungal-resistant maize cultivars is one strategy used to decrease contamination. Successful development and identification of resistant maize genotypes require evaluation of resistance including the performance of both fungus and maize during infection. In this study, we employed an RNA based quantification method using qRT-PCR to relatively quantify viable fungal tissue as well as compare the performances of both host and pathogen at different time points after inoculation. Our results suggest that A. flavus actively proliferates in both genotypes past 2 days after inoculation (dai); however, in resistant Mp313E maize growth is suppressed and reduced by 7 dai. In addition to these differences in growth, the expression profile of the aflatoxin biosynthetic pathway genes suggests that onset of aflatoxin production is earlier in the Va35 maize genotype compared to the resistant counterpart.