Association Mapping for Agronomic Traits in an Elite Spring Wheat Panel Under Drought and Irrigated Conditions

Drought is a major abiotic stress that affects the overall agronomic performance of wheat (Triticum aestivum L.).  An elite spring wheat panel of 250 breeding lines and cultivars from different wheat breeding institutions in North America and CIMMYT were evaluated for two years under drought and irrigated conditions.  A genome-wide association mapping approach using 1780 single nucleotide polymorphisms (SNPs) was conducted for nine agronomic traits (heading date, plant height, peduncle length, spike length, above-ground biomass, harvest index, grain yield, test weight and whole grain protein). A total 371 marker-trait associations (MTA’s) were detected. Of these, 142 and 170 MTA’s are unique for drought and irrigated conditions, respectively. Another 59 MTA’s were significant across conditions and years. Intrachromosomal location of many of these coincided with known major genes and published quantitative trait loci. However, new loci identified in this study can provide opportunities to improve wheat performance especially under yield limiting conditions.