Association mapping of Stagonospora nodorum blotch resistance in modern European winter wheat varieties

Abstract

Association mapping in populations relevant for wheat breeding has a large potential for validating and fine-mapping QTLs identified in F2- or DH (double haploid)-derived populations. In this study, associations between markers in the region of QSng.sfr-3BS, a major QTL for resistance to Stagonospora nodorum glume blotch (SNG), and SNG resistance were investigated by linkage and association analyses. After increasing marker density in 240 F(5:7) recombinant inbred lines (RILs), QSng.sfr-3BS explained 43% of the genetic variance and peaked 0.6 cM proximal from the marker SUN2-3B. Association between SNG resistance and markers mapped in the region of QSng.sfr-3BS was investigated in a population of 44 modern European winter wheat varieties. Two genetically distinct subpopulations were identified within these lines. In agreement with linkage analyses, association mapping by a least squares general linear model (GLM) at marker loci in the region of QSng.sfr-3BS revealed the highest association with SNG resistance for SUN2-3B (p < 0.05). Association mapping can provide an effective mean of relating genotypes to complex quantitative phenotypes in hexaploid wheat. Linkage disequilibrium (r (2)) in chromosome 3B extended less than 0.5 cM in 44 varieties, while it extended about 30 cM in 240 RILs, based on 91 SSR and STS marker-pair comparisons. This indicated that the association mapping population had a marker resolution potential at least 390-fold higher compared to the RIL population.

Field level evaluation of rice introgression lines for heat tolerance and validation of markers linked to spikelet fertility

“…The number of genotypes used is not large enough for a new study on association mapping where QTLs have to be mapped. However, the number is adequate (considering also our limitations of handling large population) for validating QTLs already reported as in our study and also several other previous such studies on wheat (44 genotypes, Tommasini et al 2007) soybean (44 genotypes, Singh et al 2008) and rice (40 genotypes, Vannirajan et al 2012). Moreover, clear population structure was observed using 48 genotypes (including four sets of elite × wild derived introgression lines, landraces and mutants) thus permitting genome-wide association mapping.…”

Evaluation and Association Mapping of Resistance to Tan Spot and Stagonospora Nodorum Blotch in Adapted Winter Wheat Germplasm

“…Furthermore, we identified 24 QTL with −log 10 (P value) >3.0 for resistance to the disease caused by the five isolates. Tommasini et al (2007) reported the detection of a major SNB resistance QTL on 3BS using an association mapping approach with only 44 European winter wheat cultivars.…”

“…Several studies have been done to map resistance to the two diseases using the association mapping approach Gurung et al 2011;Kollers et al 2014;Patel et al 2013;Tommasini et al 2007). Because different marker types (simple sequence repeat or diversity arrays technology) have been used, it is difficult to compare Table 4.…”

Fine mapping, physical mapping and development of diagnostic markers for the Rrs2 scald resistance gene in barley

“…By analysing a collection of cultivars instead of a segregating population it is possible to obtain a much higher marker resolution as was demonstrated by the study of Tommasini et al (2007), who observed a 390-fold higher marker resolution with a collection of 44 winter wheat cultivars compared to a RIL population.…”