Mapping QTLs for grain dormancy on wheat chromosome 3A and the group 4 chromosomes, and their combined effect

Abstract

A major QTL for grain dormancy, QPhs.ocs-3A.1, derived from the highly dormant wheat Zenkoujikomugi (Zen), has been identified in a study made under a controlled environment. Further investigations were needed to dissect the precise position and expression of QPhs.ocs-3A.1 under different field conditions because the ability to detect genetic loci for grain dormancy traits is compromised by environmental effects and genotype/environment interactions. Group 4 chromosomes have also been shown to be possible sites of QTLs for grain dormancy. The objectives of this study were (1) to locate additional molecular markers in the QPhs.ocs-3A.1 region, (2) to identify QTLs on the group 4 chromosomes and (3) to elucidate their combined effects. We examined the recombinant inbred lines (RILs) from a cross between Chinese Spring (CS) and Zen over a 3-year period in one location and 1 year in a different location. In an interval mapping study QPhs.ocs-3A.1 was mapped to within the 4.6 cM region flanked by Xbarc310 and Xbcd907 at the proximal end of the short arm of chromosome 3A. QPhs.ocs-3A.1 was confirmed to be the predominant dormancy QTL since it explained a large portion (11.6-44.8%) of the phenotypic variation, and was strongly displayed under dormancy-breaking conditions or at low germination temperatures. For QPhs.ocs-4A.1, identified on the long arm of chromosome 4A, and QPhs.ocs-4B.1, on the centromeric region of the long arm of Chr 4B, the LOD peak positions and the desirable allele were consistent between the trials, while the LOD scores and contribution to the phenotypic variation varied. Transgressive segregants were observed among the 125 RILs and most of them had a combination of the three alleles conferring a higher dormancy: the Zen alleles at QPhs.ocs-3A.1 and QPhs.ocs-4A.1 and the CS allele at QPhs.ocs-4B1. This demonstrated a combined effect of the desirable alleles on accelerating grain dormancy, with their total effect being superior to that of Zen.

Maximizing the identification of QTL for pre-harvest sprouting resistance using seed dormancy measures in a white-grained hexaploid wheat population

“…In Arabidopsis, MFT was discovered as homolog of FLOWERING LOCUS T (FT), a floral promoter and TERMINAL FLOWER 1 (TFL1), floral inhibitor (Hedman et al 2009). Interestingly, in wheat, these MFT homologs (TaMFT) colocalized with the seed dormancy QTL QPhs.ocs-3A.1 on chromosome 3A (Mori et al 2005). In a subsequent study, Liu et al (2013) cloned the gene TaPHS1 underlying the QTL Qphs.pseru-3AS on the short arm of chromosome 3A in white-seeded wheat using comparative and map-based cloning approaches.…”

Quantitative trait loci for resistance to pre-harvest sprouting in US hard white winter wheat Rio Blanco

“…Therefore, this QTL is not linked to red seed color and is independent from the Red gene. The QTL QPhs.ocs-3A1 on 3AS from red wheat cultivar Zen (Mori et al 2005) is about 2 cM distal to QPhs.pseru-3AS from Rio Blanco identiWed in this study according to Xbarc321 that is a closely linked marker to both QTLs (Song et al 2005), thus they could be the same QTL. The discrepancy in locations of the two QTLs could be due to the diVerence in genetic backgrounds and environmental conditions for PHS evaluation.…”

“…These QTLs were derived from white wheat cultivars and are not related to any Red genes; therefore, they can be used to breed white wheat for improved PHS resistance. Several recent studies demonstrated a major QTL for PHS on the short arm of 3A of the Japanese red wheat cultivar Zen (Miura et al 2002;Mori et al 2005;Osa et al 2003), but whether it exists in white wheat remains unknown. In the current study, one major QTL, QPhs.pseru-3AS, was repeatedly detected on chromosome 3A of a white wheat cultivar Rio Blanco.…”

“…Pre-harvest sprouting is mainly due to early breakage of seed dormancy and can lower wheat grain yield signiWcantly through reduced test weight and negatively aVect end-use quality of Xour products, substantially reducing grain sale price (Bentsink et al 2006;Groos et al 2002;Mori et al 2005). Poor Xour quality caused by PHS directly translates to low bread-making quality.…”

“…Several recent studies demonstrated that the major QTL on 4AL is present in both white and red wheat cultivars of diverse origins (Chen et al 2007;Lohwasser et al 2005;Mares et al 2005;Torada et al 2005). Although QTLs for PHS resistance have been identiWed on many chromosomes in diVerent studies, chromosome 4A and all long arms of group 3 chromosomes appear to be more critical for PHS resistance (Flintham and Gale 1996;Groos et al 2002;Kato et al 2001;Kulwal et al 2004;Mori et al 2005;Osa et al 2003).…”