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Examining MAT1-1 strain as biocontrol agent against aflatoxigenic Aspergillus flavus in maize

Jane Marian Luis: North Carolina State University

<div>Maize production in the Southern United States is frequently threatened by infection with toxigenic strains of <em>Aspergillus flavus</em> that contaminate kernels with aflatoxin. Biocontrol using nonaflatoxigenic <em>A. flavus</em> strains can reduce aflatoxin contamination by ≤95%. Efficacy can be maximized when the biocontrol strain is genetically similar to the native population of <em>A. flavus</em> in the soil. The commercial biocontrol products in the United States, AF36 and AflaGuard, and most reported biocontrol strains are <em>MAT1-2</em>. In this study, we are examining the efficacy of using a <em>MAT1-1</em> strain (RMb10) in reducing aflatoxin contamination and its influence in the native population of <em>A. flavus</em> in the soil. AflaGuard and RMb10 were applied in replicated trials in North Carolina, Mississippi and Texas in 2016, and including Alabama in 2017. Soil samples (100 g) were collected from 20 georeferenced points in each field before treatment with biocontrol and at harvest. We recovered a range of 1- 979 colony forming units of <em>A. flavus</em> per gram of soil, where colony counts are higher during harvest compared to pre-treatment with biocontrol. A set of 30 isolates per soil sample collection are being processed for double digest RAD sequencing to examine the population structure of <em>A. flavus</em> in each trial. Results of the study could be useful in developing additional biocontrol products for managing aflatoxin contamination in maize.</div>