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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Improvement of Maize with Enhanced Resistance to Aflatoxin and Insects

Location: Corn Host Plant Resistance Research

Title: Whole genome association study for drought, aflatoxin resistance, and important agronomic traits in maize in a sub-tropical environment

Authors
item Farfan, Ivan -
item DE La Fuente, G. -
item Murray, Seth -
item Isakeit, T. -
item Huang, P.C. -
item Warburton, Marilyn
item Williams, William
item Windham, Gary
item Kolomeits, M. -

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 16, 2013
Publication Date: N/A

Interpretive Summary: Drought and aflatoxin contamination from the fungus Aspergillus flavus reduce yield in many of the subtropical maize growing areas of the world. A genome wide association mapping study of maize found regions of the chromosome associated with yield, yield under drought, plant and ear height, and flowering time, but no associations with aflatoxin accumulation resistance. However, there were aflatoxin resistant lines in the population under study, which may be useful for future breeding projects. Identification of chromosomal regions associated with yield and resistance to drought stress will facilitate development of maize varieties or hybrids that are more productive in subtropical maize growing areas.

Technical Abstract: The primary maize (Zea mays L.) production areas are in temperate regions throughout the world, where most maize breeding is focused. Important but lower yielding maize growing regions, such as the sub-tropics, experience unique challenges the greatest of which are drought stress and aflatoxin contamination. Here we used a diversity panel consisting of 346 maize inbred lines originating in temperate, sub-tropical and tropical areas, testcrossed to stiff-stalk line Tx714 to investigate these traits. Testcross hybrids were evaluated under irrigated and non-irrigated trials for yield, plant height, ear height, days to anthesis, days to silking and other agronomic traits. Irrigated trials were also inoculated with Aspergillus flavus and evaluated for aflatoxin content. Diverse maize inbred lines outperformed commercials checks for most of the trials, which clearly indicate the potential of diversity in sub-tropical breeding programs. To identify genomic regions associated with yield, aflatoxin resistance and other important agronomic traits, a genome wide association analysis was performed. Using 60000 SNPs this study found 13 quantitative trait variants for grain yield, plant and ear height, and flowering time after stringent multiple test correction. Three of these variants explained 5-10% of the variation in grain yield under both water conditions. This study demonstrated the potential of genome wide association studies to identify major variants of quantitative and complex traits such as yield under drought and aflatoxin resistance that are still segregating in elite inbred lines.

Last Modified: 12/20/2014
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