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Facilitate marker assisted corn breeding efforts as well as development of transgenic cotton to enhance resistance to aflatoxin contamination. Identify genes encoding resistance associated proteins (RAPs), e.g., antifungal, stress responsive, or interfering with toxin signaling pathways, in developing and mature corn kernels through transcriptional profiling of Aspergillus flavus infected corn seed. Determine if hyperdiversity in aflatoxigenicity is driven by variation in nuclear composition.
Approach:
Aspergillus flavus microarrays containing the 5,200 expressed gene sequences will be analyzed for identification of specific genes involved in plant-fungal interactions, as well as those expressed under conditions conducive to aflatoxin production in the fungus. Histological examination of fungal colonization within the seed will be used to identify seed tissues that are most impacted by Aspergillus flavus during the infection process. Nuclear diversity in Aspergillus flavus and Aspergillus parasiticus that are either aflatoxigenic or nontoxigenic will be examined by using 1) qPCR of parents and offspring derived from sexual crosses and 2) differential labeling of nuclei in several homokaryons derived by sorting conidia with a single nucleus and setting up parasexual and sexual crosses to monitor nuclear inheritance. Offspring will be grown serially in culture to track changes in nuclear ratios over several generations of asexual growth and will also be inoculated on corn to determine if crops are selecting for specific toxin (nuclear) traits. The possibility of supernumerary/dispensable chromosomes influencing toxicity will also be explored using protoplasting and karyotyping methods.