Association Mapping of Bacterial Leaf Streak (BLS) Resistance in Hard Winter Wheat

Bacterial leaf streak (BLS) caused by Xanthomonas campestris pv. translucens is the major bacterial disease threatening to wheat production in US Northern Great Plains. It is a sporadic but wide – spread disease of wheat that can cause significant loss. Unlike fungal diseases, bacterial diseases can only be countered by developing disease resistance cultivars. Identification and characterization of genomic regions of wheat that confer resistance to BLS can be an effective way to mobilize resistance genes in wheat breeding. Association mapping holds a great promise in the dissection of complex quantitative genetic traits in plants. We screened an Association Mapping (AM) panel of 300 winter wheat cultivars representing the entire US winter wheat region for reaction to BLS. The bacterial inoculum was infiltrated into the leaf of seedlings at three – leaf stage and the expansion of the leaf area infiltrated was recorded 14 days after infiltration. The AM panel has already been genotyped using Infinium 90K array under USDA – TCAP. We identified three genomic regions using compressed mixed linear models that regulate resistance to bacterial leaf streak in wheat. These resistant – moderately resistant varieties/lines identified in the study can be used in breeding programs for developing BLS resistant wheat varieties.