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Published Articles from USDA ARS National Program 108: Food Safety
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Title: Evaluation of resistance to aflatoxin contamination in kernels of corn genotypes using a GFP-expressing Aspergillus flavus strain
Authors: Rajasekaran K, Sickler CM, Brown RL, Cary JW, Bhatnagar D
Journal: World Mycotoxin J
Accepted date: 2013 Mar 5
Interpretive summary: Aflatoxins produced by Aspergillus spp. contaminate diverse food and feed crops including corn, cotton, peanuts and tree nuts. Identification of native resistant genes in germplasm is essential for conventional or molecular crop breeding programs. Unfortunately, resistance to this group of saprophytic fungi is very rare in cultivated crops due to lack of precise host-pathogen relationship. However, in corn, several genotypes have been identified as resistant to aflatoxin contamination due to several factors such as physical barriers (e.g., wax or tough seed coat) or the presence of antifungal proteins in corn kernels. To be successful in breeding programs, it is equally important to know how the fungus invades maize kernels so that objectives of conventional or molecular breeding for tissue or organ specific expression of resistant factors or genes. Recently we utilized an aflatoxigenic A. flavus strain, engineered to express the green fluorescent protein from the jelly fish, to study the site of entry, fungal growth and colonization in corn kernels. We observed that the predominant site of entry is through the stalk or pedicel unless the kernels are injured by insect or other damages. This method of assaying for resistance to the fungus is very sensitive, rapid and simple and can be used to track the fungal colonization in real time. This simple method will be very useful to breeders, geneticists, agronomists and biotechnologists alike who are interested in evaluating germplasm for resistance to Aspergillus.
Publication date: 2013 May
Volume: 6
Issue: 2
Pages: 151-8