Project Number: 6602-21000-021-00
Project Type: Appropriated

Start Date: May 19, 2008
End Date: May 18, 2013

Objective:
(1) Develop peanut genomic tools and strategies to elucidate the molecular mechanisms that define crop defense pathways and regulation of resistance to diseases such as tomato spotted wilt virus (TSWV), leaf spots and aflatoxin contamination in peanut. (2) Evaluate corn germplasm that harbors resistance genes that reduce aflatoxin contamination and understand the responding genes and pathways in corn.

Approach:
(1) Replicated laboratory and field screening and evaluation of peanut accessions for disease resistance will be conducted in order to identify the ¿resistant¿ germplasm for further genomic studies. The resistant germplasm will be utilized in molecular marker development for marker-assisted breeding. (2) ESTs (expressed sequence tags) will be generated from cDNA libraries constructed from seed and leaf tissues of two genotypes, Tifrunner and GT-C20. EST-derived SSR markers will be developed and peanut oligo-microarray will be produced for gene expression study. (3) Genetic mapping populations (RILs, recombinant inbred lines) will be produced from crosses of Tifrunner and GT-C20, and SunOleic 97R x NC94022. QTL mapping will be conducted for resistance to tomato spotted-wilt virus (TSWV) and leaf spots, and aflatoxin contamination. (4) Microarray experiments will be used to identify candidate genes in corn-Aspergillus flavus and drought stress interactions that are turned on or off during corn kernel development. The candidate genes identified from microarray will be verified or confirmed through real time PCR or other well established methods. Another goal is to develop a macroarray tool (membranes) using these candidate genes from microarray to assess resistance or drought tolerance in corn germplasm for their stability of expression in native crops under environmental conditions (e.g., drought) known to be conducive to aflatoxin contamination. The genes identified in corn kernels also will be applied in searching possible `orthologs¿ in peanut genome and peanut germplasm.