Abstract
Wheat powdery mildew (PM), caused by Blumeria graminis f. sp. tritici, is a major fungal disease of wheat worldwide. It can cause considerable yield losses when epidemics occur. Use of genetic resistance is the most effective approach to control the disease. To determine the genomic regions responsible for PM resistance in a set of U.S. winter wheat and identify DNA markers in these regions, we conducted a genome-wide association study on a set of 185 U.S. winter wheat accessions using single nucleotide polymorphism (SNP) markers from 90 K wheat SNP arrays. We identified significant SNP markers linked to nine quantitative trait loci (QTLs) and simple sequence repeats (SSR) markers linked to three QTLs for PM resistance. Most of the QTLs in the US winter wheat population have been reported previously, but some such as these on chromosomes 1A, 6A and 1B have not been reported previously, and are likely new QTLs for PM resistance in U.S. winter wheat. The germplasm with immunity to PM are good sources of resistance for PM resistance breeding and the markers closely linked to the QTLs can be used in marker-assisted selection to improve wheat PM resistance after further validation.
Highlights
Wheat (Triticum aestivum L.) is one of the staple food crops and serves nearly 35% of the world populations[1]
The correlation coefficients of powdery mildew (PM) scores were all significant among the four experiments and was the highest between 2010 and 2011 greenhouse experiments (r = 0.762) and the lowest between 2013 field and 2013 greenhouse (r = 0.466) experiments, suggesting that some adult plant resistance genes expressed in the field experiment might be different from these expressed in seedling stage in the greenhouse experiments
Wheat cultivars from NRPN were mostly clustered to Group I and wheat cultivars from Regional Germplasm Observation Nurseries (RGON) and SRPN were mostly clustered to Group I and Group II, whereas accessions in Uniform Southern Soft Red Winter Wheat Nursery (USSRWWN) and Uniform Eastern Soft Red Winter Wheat Nursery (UESRWWN) showed higher PM resistance and clustered into Group III
Summary
Wheat (Triticum aestivum L.) is one of the staple food crops and serves nearly 35% of the world populations[1]. Some Pm genes were identified from non-progenitor species of wheat, including Pm7, Pm8, Pm17, Pm20 and PmCn17 from Secale cereal, Pm21 from Haynaldia villosa, and Pm40 and Pm43 from Thinopyrum intermedium[23,24,25,26,27,28,29,30]. Most of these genes have been used in breeding for PM resistance in wheat. Population structure (Q) and genetic relatedness (Kingship) can be integrated together into a statistical model for association analysis to reduce such false association[46,47]
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