Dominant male-sterile populations for association mapping and introgression of exotic wheat germplasm

The introgression of exotic wheat germplasm such as synthetic hexaploid (tetraploid × diploid amphiploid) wheat ( Triticum aestivum L.) into an adapted gene pool has the potential to amplify the genetic variation for complex traits. The dominant male-sterile gene can be used to facilitate recurrent selection in wheat, thus increasing the opportunity for genetic recombination between exotic and cultivated genomes and the identification and retention of desirable alleles. Our dominant male-sterile recurrent selection project began in 1983 with the intermating of the source germplasm (Chris hard red spring wheat in Triticum tauschii cytoplasm) with 34 soft winter lines and varieties, intermated without selection for 3 generations, and then selecting male-sterile plants for agronomic type each season. After 20 generations of recurrent selection, we extracted 94 inbred lines without selection during inbreeding except for fertility. Those lines were evaluated for linkage disequilibrium (LD) on the 5A chromosome for comparison with an earlier study involving 95 elite soft winter wheat varieties of similar genetic background. For the male-sterile population-derived lines, LD decayed within 1 cM ( r 2