Abstract
The durum wheat line DT696 is a source of moderate Fusarium head blight (FHB) resistance. Previous analysis using a bi-parental population identified two FHB resistance quantitative trait loci (QTL) on chromosome 5A: 5A1 was co-located with a plant height QTL, and 5A2 with a major maturity QTL. A Genome-Wide Association Study (GWAS) of DT696 derivative lines from 72 crosses based on multi-environment FHB resistance, plant height, and maturity phenotypic data was conducted to improve the mapping resolution and further elucidate the genetic relationship of height and maturity with FHB resistance. The Global Tetraploid Wheat Collection (GTWC) was exploited to identify durum wheat lines with DT696 allele and additional recombination events. The 5A2 QTL was confirmed in the derivatives, suggesting the expression stability of the 5A2 QTL in various genetic backgrounds. The GWAS led to an improved mapping resolution rendering the 5A2 interval 10 Mbp shorter than the bi-parental QTL mapping interval. Haplotype analysis using SNPs within the 5A2 QTL applied to the GTWC identified novel haplotypes and recombination breakpoints, which could be exploited for further improvement of the mapping resolution. This study suggested that GWAS of derivative breeding lines is a credible strategy for improving mapping resolution.
Highlights
The durum wheat line DT696 is a source of moderate Fusarium head blight (FHB) resistance
Variance analysis was conducted for the FHB traits as well as plant height and maturity for 223 DT696 derivatives phenotyped in Morden and Brandon FHB nurseries in Manitoba, Canada in 2016 and 2017
Considering the co-localization of plant height and maturity with FHB resistance quantitative trait loci (QTL) reported in the previous study[2], covariance analysis conducted with either plant height or maturity assigned as a covariate to test the dependency of FHB resistance expression on these traits
Summary
The durum wheat line DT696 is a source of moderate Fusarium head blight (FHB) resistance. Since its introduction as a source of moderate FHB resistance in the durum wheat breeding program at the Swift Current Research and Development Centre of the Agriculture and Agri-Food Canada (AAFC SCRDC), DT696 and its derivatives have been used as parents in several hundred crosses This has provided an opportunity for the application of a genome wide association study (GWAS) for improving mapping resolution of FHB resistance QTL through the identification of novel recombination events at the 5A1 and 5A2 loci. It has provided the opportunity for validating the 5A1 and 5A2 QTL and deciphering the type of the association of FHB resistance with plant height and maturity reported repeatedly in previous studies[2,8,11,14]. GWAS is valuable for validating and high-resolution mapping of the FHB resistance QTL previously identified through bi-parental mapping such as the 5A1 and 5A2 QTL
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