|KORANI, WALID AHMED - University Of Georgia|
|CHU, YE - University Of Georgia|
|Holbrook, Carl - Corley|
|CLEVENGER, J - University Of Georgia|
|OZIAS-AKINS, P - University Of Georgia|
Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2018
Publication Date: 1/25/2018
Citation: Korani, W., Chu, Y., Holbrook Jr, C.C., Clevenger, J., Ozias-Akins, P. 2018. Genotypic regulation of aflatoxin accumulation but not Aspergillus fungal growth upon post-harvest infection of peanut (Arachis hypogaea L.) seeds. Toxins. 9:218.
Interpretive Summary: Peanut is one of the most susceptible crops to Aspergillus flavus infection either in the field (pre-harvest) or during storage (post-harvest). Under conducive environmental conditions, A. flavus produces aflatoxins which can cause toxicosis, cancer, and immunosupressive disease in animals including humans. Aflatoxin contamination costs the U.S. peanut industry over $20 million annually. The objective of this study was to evaluate peanut genotypes to attempt to identify sources of resistance. Genetic differences were observed in response to A. flavus fungal growth and aflatoxin production. Peanut germplasm ICG 1471 was found to inhibit aflatoxin production without restraining fungal growth. Rainout shelter testing also showed reduced aflatoxin production in ICG 1471, suggesting that this germplasm and its underlying genetic mechanisms for resistance may be useful in breeding for pre- and post-harvest aflatoxin reduction.
Technical Abstract: Aflatoxin contamination is a major economic and food safety concern for the peanut industry that largely could be mitigated by genetic resistance. To screen peanut for aflatoxin resistance, Ten genotypes were infected with green fluorescent protein (GFP) - expression Aspergillus flavus strain. Percentages of fungal infected area and fungal GFP signal intensity were documented by visual ratings every 8 h for 72 h after inoculation. Significant genotypic differences in fungal growth rates were documented by repeated measures and area under the disease progress curve (AUDPC) analyses. SICIA (Seed Infection Coverage and Intensity Analyzer), and image processing software, was developed to digitize fungal GFP signals. Data from SICIA image analysis confirmed visual rating results validating its utility for quantifying fungal growth. Among the tested peanut genotypes, NC 3033 and GT-C20 supported the lowest and highest fungal growth on the surface of peanut seeds, respectively. Although differential fungal growth was observed on the surface of peanut seeds, total fungal growth in the seeds was not significantly different across genotypes based on a fluorometric GFP assay. Significant differences in aflatoxin B levels were detected across peanut genotypes. ICG 1471 had the lowest aflatoxin level whereas Florida-07 had the highest. Two-year aflatoxin tests under simulated late-season drought also showed the ICG 1471 had reduced aflatoxin production under pre-harvest field conditions. These results suggest that all peanut genotypes support A. flavus fungal growth yet differentially influence aflatoxin production.