Poster: Plant Pathogen/Symbiont Interactions

Abs # 750: Catalase3 and maize resistance to Aspergillus flavus: a possible link?

Presenter:	Magbanua, Zenaida V, zvm2@ra.msstate.edu
Authors	Magbanua, Zenaida V (A)   Williams, W. Paul  (B)   Luthe, Dawn  (A)
Affiliations:	(A): Dept. of Biochemistry and Molecular Biology, Mississippi State University (B): USDA – ARS Corn Host Plant Resistance Unit

Zea mays L. infection by Aspergillus flavus frequently produces aflatoxin, which reaches the food chain through contaminated kernels. Since A. flavus is versatile, prolific and has a broad host range, its management and control pose a major challenge to maize farmers and breeders. Thus far, breeding for resistance has been the most useful means of control although it has not been very effective. Hence, our laboratory is working to find more durable sources of resistance and to study the mechanisms that lead to resistance to fungal growth and/or alfatoxin accumulation. In a mapping population derived from Mp313E (resistant) and Va35 (susceptible), there is a significant QTL for aflatoxin resistance on chromosome 4, near the map location for catalase3 (cat3). Therefore, we are examining the involvement of catalase in the resistance mechanism. Our previous data indicate that catalase specific activity was higher in developing embryos from resistant compared to susceptible lines. The gel activity assay also showed that the catalase isozyme from the susceptible lines migrated faster than that from the resistant lines. We are cloning cat3 cDNA from a resistant line (Mp313E) and a susceptible line (Sc212M) and comparing their nucleotide and amino acid sequences. Our preliminary data suggest that the mRNA in the susceptible line maybe truncated. We are performing more experiments to verify these results and to analyze the possible role of cat3 in maize resistance to A. flavus.