Association mapping of yellow pigment in an elite collection of durum wheat cultivars and breeding lines

Abstract

Association mapping (AM) is an alternative or complementary strategy to QTL mapping for describing associations between genotype and phenotype based on linkage disequilibrium (LD). Yellow pigment (YP), an important end-use quality trait in durum wheat (Triticum turgidum L. var. durum), was evaluated to determine the ability of AM to identify previously published QTL and to identify genomic regions for further genetic dissection. The YP concentration was determined for 93 durum wheat accessions sampled from a variety of geographic origins. Analysis of population structure using distance- and model-based estimates indicated the presence of five subpopulations. Using subpopulation assignments as covariates, significant (P < 0.05) marker-trait associations for YP were detected on all chromosomes of the durum genome. Using AM, genomic regions housing known YP QTL were confirmed, most notably the group 7 chromosomes. In addition, several markers on the group 1, 2, and 3 chromosomes were identified where QTL have yet to be reported. A phytoene synthase gene, Psy1-B1, a potential candidate gene for YP, was significantly associated with YP and was in strong LD with microsatellite markers on the distal end of 7BL. Our results demonstrated that AM complemented traditional QTL mapping techniques and identified novel QTL that should be the target of further genetic dissection.

Improving durum wheat (Triticum turgidum L. var durum) grain yellow pigment content through plant breeding

“…Thus, the percentages of explained vari-the nine Chilean durum wheat genotypes studied exhibited the same PCR banding pattern with both the PSY1Al and PSY1Ba alleles (Figure 3 and 4), which are associated with intermediate (Singh et al, 2009) and low levels of GYPC (Reimer et al, 2008;, respectively, in agreement with the phenotypic results previously reported (Figure 1). …”

“…The effect of the PSY1D locus on the yellowness of the endosperm has been less well studied, but recent evidence shows that it also significantly influences this trait (Ravel et al, 2013). However, the percentages of endosperm yellowness or GYPC variability explained by the PSY1 loci are not reported in several studies (Pozniak et al, 2007, Reimer et al, 2008Dubcovsky, 2008, He et al, 2009a;He et al 2009b;Singh et al, 2009). Therefore, those values previously mentioned are only a partial sample of all cases in which the homeologous PSY1 loci have been studied so far (Schulthess, 2013).…”

“…Concerning PSY1B, the two allelic variants correspond to PSY1Ba (220 bp, lower semolina yellowness) and PSY1Bb (200 bp, higher yellowness) (Reimer et al 2008; (Figure 4). In this work, …”

“…Additionally, in other studies (see as examples Pozniak et al, 2007 andHe et al, 2009a) the variation within these loci simply had no significant association with the endosperm yellowness. Moreover, raised the possibility that a second gene (or another regulatory element) is involved in control- (Reimer et al, 2008), and Strongfield (154) (Reimer et al, 2008) and UC 1113 (88) ling wheat endosperm yellowness and maps very close to PSY1 on the long arm of chromosome 7. There is some evidence reported to support this idea.…”

The colours of durum wheat: a review

“…Significant marker-trait associations for YPC have been detected on all of the chromosomes by linkage mapping (Parker et al 1998;Hessler et al 2002;Pozniak et al 2007;Patil et al 2008;Zhang et al , 2009Howitt et al 2009;Blanco et al 2011;Roncallo et al 2012) and by association mapping (Reimer et al 2008).…”