Poster: Plant-pathogen interactions

Abs # 503: Catalase3+: evolving a new role in maize resistance to Aspergillus flavus

Presenter:	Magbanua, Zenaida V., zvm2@ra.msstate.edu
Authors	Magbanua, Zenaida V. (A)   Williams,  W. Paul  (B)   Luthe, Dawn S. (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 is an interest not only to farmers and breeders but to basic scientists as well. Our laboratory is investigating resistance to this fungus, which is a quantitative trait in maize. 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). Catalase is an enzyme that dismutates H2O2 into H2O and O2, and is believed to be a signaling molecule in plant-pathogen interactions. Consequently, we hypothesized the involvement of catalase in maize resistance to A. flavus. We have shown that the catalase levels of embryos are significantly higher in resistant compared to susceptible lines. We have also cloned and sequenced cat3 from resistant and susceptible lines. Our current data show that the resistant lines are missing the second intron of cat3. We speculate that cat3 maybe evolving a new function in this interaction. To further investigate the role of catalase in conferring resistance, we will measure the levels of H2O2 in the resistant and susceptible maize lines. The analyses of these data will be presented and the possible role of catalase in maize resistance to A. flavus will be discussed.