Genome-Wide Association Study for Adult-Plant Resistance to Stripe Rust in Chinese Wheat Landraces (Triticum aestivum L.) From the Yellow and Huai River Valleys

Abstract

Stripe rust (also known as yellow rust), caused by the pathogen Puccinia striiformis f. sp. tritici ( Pst ), is a common and serious fungal disease of wheat ( Triticum aestivum L.) worldwide. To identify effective stripe rust resistance loci, a genome-wide association study was performed using 152 wheat landraces from the Yellow and Huai River Valleys in China based on Diversity Arrays Technology and simple sequence repeat markers. Phenotypic evaluation of the degree of resistance to stripe rust at the adult-plant stage under field conditions was carried out in five environments. In total, 19 accessions displayed stable, high degrees of resistance to stripe rust development when exposed to mixed races of Pst at the adult-plant stage in multi-environment field assessments. A marker–trait association analysis indicated that 51 loci were significantly associated with adult-plant resistance to stripe rust. These loci included 40 quantitative trait loci (QTL) regions for adult-plant resistance. Twenty identified resistance QTL were linked closely to previously reported yellow rust resistance genes or QTL regions, which were distributed across chromosomes 1B, 1D, 2A, 2B, 3A, 3B, 4A, 4B, 5B, 6B, 7A, 7B, and 7D. Six multi-trait QTL were detected on chromosomes 1B, 1D, 2B, 3A, 3B, and 7D. Twenty QTL were mapped to chromosomes 1D, 2A, 2D, 4B, 5B, 6A, 6B, 6D, 7A, 7B, and 7D, distant from previously identified yellow rust resistance genes. Consequently, these QTL are potentially novel loci for stripe rust resistance. Among the 20 potentially novel QTL, five ( QDS.sicau-2A , QIT.sicau-4B , QDS.sicau-4B.2 , QDS.sicau-6A.3 , and QYr.sicau-7D ) were associated with field responses at the adult-plant stage in at least two environments, and may have large effects on stripe rust resistance. The novel effective QTL for adult-plant resistance to stripe rust will improve understanding of the genetic mechanisms that control the spread of stripe rust, and will aid in the molecular marker-assisted selection-based breeding of wheat for stripe rust resistance.

Genome-wide Association Mapping Reveals Potential Novel Loci Controlling Stripe-rust Resistance in a Chinese Wheat Landrace Diversity Panel From the Southern Autumn-sown Spring Wheat Zone

“…Yrsicau-5B was anked by the marker 4408847. In a previous study, QYr.sicau-5B.3 and QIT.sicau-5B.2 were located close to this QTL region containing Yr74 [30,31,48]. QYr.6AL was anked by Xgwm617 in three environments [49] and Yrsicau-6A.1 was located close to the QTL region.…”

“…Yrsicau-6B.1 and Yrsicau-6B.2 were signi cantly associated with IT in response to CYR32 and CYR34, respectively. There are many QTLs and two genes were closely mapped with Yrsicau-6B.1, such as QYr.ufs-6B, QYr.caas-6BS.2, QYr.sicau-6B, QDS.sicau-6B.1, Yr35 and Yr78 [30,31,[50][51][52][53]. These results indicate that these chromosomal regions may be 'hotspot' regions for stripe-rust resistance genes [20].…”

“…was tagged by the marker 993667 and closely mapped with YrSph, which provides resistance to Pst race CYR32 in the eld [38]. Yrsicau-2A also closely mapped with QIT.sicau-2A.1 [30]. Yrsicau-2B.1 and Yrsicau-2B.2 were associated with resistance to CYR32.…”

“…In the same region in the vicinity of Xgwm146, a stripe-rust resistance QTL was identi ed as QYr-7BL [55] and a seedling stripe-rust resistance gene temporarily designated YrSuj was located in a 0.6 cM interval containing Xcfa2040 and Xwmc526 [56]. QIT.sicau-7D, QDS.sicau-7D.2 and QDS.sicau-7D.3 were anked by Xcfd14, 2242944 and Xcfd68, respectively, as reported previously [30]. These loci were close to the marker Xgwm111 that anked Yrsicau-7D in the current study.…”

“…They have a greater diversity of genes that respond to abiotic and biotic stresses, such as growth habit; cold; heat or drought tolerance; early growth vigor; competition with weeds and disease tolerance [27]. They could be used as important resources for stripe-rust resistance breeding [12,20,[28][29][30][31]. However, relatively few studies have investigated genetic diversity and stripe rust resistance in wheat landraces from the southern autumnsown spring wheat zone of China.…”