Determination and evaluation of the sequence and textural effects of the puroindoline a and puroindoline b genes in a population of synthetic hexaploid wheat.

Aegilops tauschii (2 n=2 x=14, DD) is a rich source of genetic variability for hexaploid wheat ( Triticum aestivum, 2 n=6 x=42, AABBDD) improvement. This variability can be accessed through utilizing synthetic hexaploid wheat lines, which contain genomes from Ae. tauschii and T. turgidum (2 n=4 x=28, AABB). Numerous desirable characteristics can and have been introgressed into common hexaploid wheat with this germplasm. In this work, the genetic variability in the two puroindoline genes (a and b) contained on the D genome, and the relationship that sequence polymorphisms in these genes have on endosperm texture among a population of 75 CIMMYT synthetic hexaploid accessions is described. Kernel texture was evaluated using the single kernel characterization system (SKCS). Kernel texture differed significantly ( P<or=0.0001) among the synthetic hexaploid accessions (range 2.6-40.9) and the parent types, durum or Ae. tauschii. The interaction term between parent types was also a significant effect ( P<or=0.0001). In addition to the 'wild-type' protein sequences of the puroindoline genes (those present in 'Chinese Spring' and all other soft wheats), three other translated sequences were identified in puroindoline a and two others in puroindoline b. These protein sequences were associated with significantly ( P<or=0.0001) softer endosperm textures than the wild-type protein sequences. As the softer alleles are expressed in a hexaploid background, they are immediately available to wheat breeding programs.