Molecular mapping of QTL for leaf spot disease complex resistance in spring wheat
Berraies, S., Cuthbert, R., Knox, R., Henriquez, M.A., Burt, A., Kumar, S., Ruan, Y., Pozniak, C.J., N’Diaye, A., Sharpe, A., and Bokore, F. 2016. Molecular mapping of QTL for leaf spot disease complex resistance in spring wheat. 3rd Canadian Wheat Symposium (CWS), Ottawa, November 22-25.
The leaf spot disease complex (LSDC) (tan spot, septoria leaf blotch complex and spot blotch) is one of the most prevalent and widespread wheat diseases in Western Canada, reducing test weight and limiting production. Genetic resistance to LSDC is essential to reduce losses of grain yield. This study was conducted to identify DNA markers for LSDC resistance in adapted germplasm of spring wheat. A doubled haploid population of 180 lines was developed from the cross of LSDC moderately resistant to moderately susceptible commercial cultivars Vesper and Carberry. The population and parental controls were field evaluated near Morden and Brandon MB for LSDC response. Continuous distributions of disease reaction in both locations indicated quantitative inheritance. Based on a linkage map that consisted of 6212 SNP markers (Infinium iSelect 90k SNP wheat array), Multiple QTL mapping (MQM) analysis revealed a significant resistance QTL on chromosome 7D detected in both locations, and a significant resistance QTL on chromosome 2D detected only in the Brandon environment. The level of phenotypic variation explained by the 7D resistance QTL was 10.8% in Brandon and 26.4% in Morden. The level of phenotypic variation explained by the 2D resistance QTL was 9.8% in Brandon. Vesper carried the favourable allele associated with LSDC resistance on chromosome 2D, while the chromosomes 7D favourable allele was derived from Carberry. The SNP markers associated with resistance QTL could be utilized to facilitate combining the QTL and to accelerate the development of LSDC resistant adapted wheat cultivars.