Association mapping in durum wheat grown in a broad range of water regimes

In major crops, panels of germplasm accessions have been assembled for allele mining at targeted candidate genes and for whole-genome association mapping studies. A germplasm collection of 189 cultivated durum wheat accessions representing the major breeding groups was tested in a broad range of Mediterranean environments under rainfed and irrigated conditions with an average yield ranging from 0.9 to 6.8 t/ha. Yield, yield components, agronomic and physiological traits were recorded in 15 trials and tested for significant association with the allelic profile of 180 microsatellite markers (simple sequence repeats, SSRs). Population structure was evaluated and the clustering data were used as covariates in the association test. SSRs showing significant associations in several environments were identified for the traits with the highest heritability values, i.e. plant height, heading date, peduncle length and kernel weight, with R2 values ranging from 5 to 10%. As to yield and yield components, most associations were detected only in two to four environments, with an average R2 value lower than 5%.