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Poster: Molecular & Cellular Plant-Microbe Interactions: Proteomics/Metabolomics/Genomics


Temporal succession of an Aspergillus flavus biocontrol agent in commercial cornfields in Texas
M. SEXTON (1), I. Carbone (1), J. White (1), T. Isakeit (2) (1) Center for Integrated Fungal Research, North Carolina State University, U.S.A.; (2) Texas A&M University, U.S.A.

Aspergillus flavus contaminates corn by producing carcinogenic aflatoxins (AF). This results in devastating economic losses worldwide and poses serious health risks. The most effective control strategy for reducing AF contamination is the application of non-aflatoxigenic strains of A. flavus, such as NRRL 21882 (=Afla-Guard®) or NRRL 18543 (=AF36). However, we have a limited understanding of the succession of biocontrol agents in cornfields. From a genomic perspective, we are examining the influence of NRRL 21882 on the populations of A. flavus from Texas commercial cornfields. In 2014, A. flavus strains were isolated from kernels from fields that were not treated or treated with NRRL 21882 in 2011. To obtain fine resolution of genetic variation, we conducted genome-wide sequencing, which allowed us to detect changes in the genomes of NRRL 21882-derived strains and introgression of NRRL 21882 into native strains over a three year period. From an analysis of 168 A. flavus strains, 32 strains are missing their entire AF gene cluster, a marker of NRRL 21882; 14 of these were in untreated fields. Eight of the strains missing the cluster are putative recombinants, phylogenetically grouping with full cluster strains. Ongoing sexual reproduction is indicated by approximately equal distributions of both mating types in treated and untreated fields.