Abstract
BackgroundStripe rust is a serious fungal disease of wheat (Triticum aestivum L.) caused by Puccinia striiformis f. sp. tritici (Pst), which results in yield reduction and decreased grain quality. Breeding for genetic resistance to stripe rust is the most cost-effective method to control the disease. In the present study, a genome-wide association study (GWAS) was conducted to identify markers linked to stripe rust resistance genes (or loci) in 93 Northern Chinese wheat landraces, using Diversity Arrays Technology (DArT) and simple sequence repeat (SSR) molecular marker technology based on phenotypic data from two field locations over two growing seasons in China.ResultsSeventeen accessions were verified to display stable and high levels of adult plant resistance (APR) to stripe rust via multi-environment field assessments. Significant correlations among environments and high heritability were observed for stripe rust infection type (IT) and disease severity (DS). Using mixed linear models (MLM) for the GWAS, a total of 32 significantly associated loci (P < 0.001) were detected. In combination with the linkage disequilibrium (LD) decay distance (6.4 cM), 25 quantitative trait loci (QTL) were identified. Based on the integrated map of previously reported genes and QTL, six QTL located on chromosomes 4A, 6A and 7D were mapped far from resistance regions identified previously, and represent potentially novel stripe rust resistance loci at the adult plant stage.ConclusionsThe present findings demonstrated that identification of genes or loci linked to significant markers in wheat by GWAS is feasible. Seventeen elite accessions conferred with stable and high resistance to stripe rust, and six putative newly detected APR loci were identified among the 93 Northern Chinese wheat landraces. The results illustrate the potential for acceleration of molecular breeding of wheat, and also provide novel sources of stripe rust resistance with potential utility in the breeding of improved wheat cultivars.
Highlights
Stripe rust is a serious fungal disease of wheat (Triticum aestivum L.) caused by Puccinia striiformis f. sp. tritici (Pst), which results in yield reduction and decreased grain quality
We evaluated 93 wheat landraces grown in the Northern Chinese wheat-growing zone (I-Northern Winter Wheat Zone and VII-Northern Spring Wheat Zone) [41] for resistance to Pst
Adult-stage responses to stripe rust and estimation of heritability In the field, we recorded the stripe rust response of the 93 wheat landraces grown in four environments at Mianyang and Chongzhou in 2016 and 2017 (Additional file 1)
Summary
Stripe rust is a serious fungal disease of wheat (Triticum aestivum L.) caused by Puccinia striiformis f. sp. tritici (Pst), which results in yield reduction and decreased grain quality. Breeding for genetic resistance to stripe rust is the most cost-effective method to control the disease. The stripe rust fungus has diversified into a large number of races possessing different combinations of virulence genes. These races have the capability of circumventing the host resistance genes, and in combination with their capacity for long-distance dispersal, subsequently creating the potential for destructive epidemics in susceptible varieties under favorable conditions [3, 4]. In China, the most severe epidemics of wheat stripe rust occurred in 1950, 1964, 1990, and 2002, and caused substantial yield losses of wheat, which were estimated at 6.00, 3.20, 2.65 and 1.40 million metric tons, respectively. Growing resistant cultivars is considered to be the most effective, environment-, and consumer-friendly means to manage stripe rust [2, 6,7,8]
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