Using the Ae. tauschii D Genome to Improve Preharvest Sprouting and α-Amylase Traits in Hexaploid Wheat.

Sprouting damage is a serious problem occurring in wheat which causes poor grain quality, reduced marketability, and profit losses for growers.  Causes of sprouting damage include preharvest sprouting (PHS), and enzymatic degradation of the starch by alpha-amylase (α-amylase).  Limited genetic variation within the D genome of wheat reduces the allelic diversity to select for improvement of D genome gene loci effecting sprouting resistance.  Low D genome diversity also means that there is potential of superior alleles in the D-genome progenitor, Ae. tauschii.  A D-genome introgression population of inbred backcross lines (IBLs) was developed by direct crossing of seven Ae. tauschii genotypes to the hexaploid wheat line, ‘KS05HW14.’  Phenotypic variation for PHS and α-amylase activity within the D genome IBLs was characterized and genomic regions harboring genes controlling PHS and α-amylase activity were identified through association analysis.  In preliminary results of 2015 field data, wide variation for both PHS and α-amylase phenotypes was observed indicating that the D genome of Ae. tauschii contains valuable genes for improving sprouting resistance in hexaploid wheat.  Strong associations of genotype with PHS were visible on 3DL and 5DL, and with α-amylase on 1DS, 2DL, and 6DL.  The results of this study will be necessary for effective identification and introgression of new sources of sprouting resistance to reduce the risk of sprouting damage in cultivated wheat.