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United States Department of Agriculture

Agricultural Research Service

Research Project: New Statistical Tools to Study Aflatoxin Genetic Resistance in Maize

Location: Corn Host Plant Resistance Research

Project Number: 6406-21000-013-12
Project Type: Specific Cooperative Agreement

Start Date: Sep 30, 2012
End Date: Oct 31, 2015

Objective:
The objective of this project is to analyze the genetic and phenotypic characterization data from new inbred lines displaying high and stable resistance to Aspergillus (A.) flavus and aflatoxin accumulation and to new genes and gene-based markers linked to these traits. Genes for resistance will be identified via association analysis orquantitative trait loci (QTL) mapping. New methodologies for efficient association mapping, including parameters for highest statistical power, will be tested. Methods to combine data from QTL mapping with association mapping will be developed.

Approach:
Considerable work has already been done in the mapping of aflatoxin and Aspergillus (A.) flavus resistance in maize, and five fully phenotyped and genotyped quantitative trait loci (QTL) mapping populations and two association mapping panels are currently available for this project. The data must now be analyzed, and utilized to identify germplasm and genes associated with high resistance. In the first year, the analysis of field phenotypes in the International Maize and Wheat Improvement Center (CIMMYT) and Corn Host Plant Resistance Research Unit (CHPRRU) association mapping panels will be done first to account for high genotype by environment interaction (GxE) and potential measurement error, correlations and covariances between traits and population substructure, and best estimators of all phenotypes calculated. This will be followed by initial association mapping of both panels. In year two, testing new methodologies for dealing with multiple testing effects, low power due to imalanced allele frequencies, and other variables affecting association mapping can be done, and further association analyses of the two panels either to confirm genes found in one panel can be identified in the second panel, or combining the two independent association panels to analyze them jointly, to see if power is improved and false positive rate reduced. Finally, in the third year, the association mapping results will be combined with results from QTL mapping studies, in order to cross-validate and also identify genes linked to resistance that cannot be identified in either type of study alone.

Last Modified: 7/25/2014
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