Towards Developing Co-Dominant Markers for Wsm1 and Cmc4 in Winter Wheat

Wheat streak mosaic (WSM), transmitted by the wheat curl mite (Acer tulipae), is a devastating disease that is becoming more widespread in its impact on winter wheat (Triticum aestivum L. 2n=6x=42, AABBDD) performance in the U.S. Great Plains. Chemical control options are not available for the disease or insect vector, and genetic resistance genes are not readily found in cultivated wheat; therefore, genetic sources in alien genomes have been exploited and introgressed into wheat. A chromosomal fragment 4Ai-2 of Thinopyrum intermedium (Host) Barkworth and Dewey containing a resistance gene against WSM (Wsm1) has been introgressed to wheat, and a chromosomal fragment containing a resistance gene in the wild wheat relative Ae. tauschii against the wheat curl mite (Cmc4) has also been introgressed to wheat. In this study, a breeding population was generated from a cross using one parental line carrying Wsm1 that traced back to KS93WGRC27 in a ‘Overley’ winter wheat background, and the other parental line carrying Cmc4 for curl mite resistance (OK05312, a winter wheat line). Markers reported to be tightly linked to the two translocated genes in previous studies are dominant. We have sequenced the markers and found orthologous sequences of the markers for the genes. Co-dominant markers for both Wsm1 and Cmc4 are being developed to facilitate mapping of Wsm1 and Cmc4 and accelerate pyramiding of the genes in bread wheat.