Association Mapping of the U.S. Peanut Minicore Collection for Tolerance to Water Deficit Stress.

The U.S. peanut minicore collection was screened over two years at two locations in West Texas, under three irrigation treatments, 75% evapotranspiration (ET) replacement (full irrigation), 50% ET replacement (mild drought) and 25% ET replacement (severe drought), with three replications in each treatment.  The minicore collection has also been evaluated at Pobé, Burkina Faso for tolerance to terminal drought stress.  Field measurements were taken at biweekly intervals in Texas during mid-season drought, extending approx. 42 to 105 DAP.   Significant differences were found among accessions for SPAD chlorophyll, flowering, paraheliotropism, and canopy temperature, as well as plot height and width near the end of the growing season, and yield.  Pod yield demonstrated that several runner accessions performed better in field response measurements in West Texas than standard cultivars.  At Pobé, Spanish accessions tended to perform the best in terms of yield.  Association mapping using SSR markers representing over 350 alleles identified markers for all traits but canopy temperature over multiple environments.  Several markers were associated with multiple traits.  We propose to use several accessions as parents to donate tolerance to water deficit stress to commercial materials, and attempt to validate the markers in segregating populations.