Mapping quantitative trait loci associated with variation in grain dormancy in Australian wheat

Abstract

Preharvest sprouting is a problem in many regions of the world, resulting in downgrading of quality, substantial economic losses to wheat growers, and difficulties for grain handling and marketing agencies. Improvements in tolerance from the introduction of better grain dormancy at, or near, harvest-ripeness would be expected to have a significant impact on the incidence and severity of sprouting. Intermediate levels of dormancy in older Australian wheats, such as Halberd, and a small number of current cultivars could be used in the short term while more extreme dormancy is being introgressed into locally adapted germplasm. A doubled haploid population derived from Cranbrook (extremely non-dormant, very susceptible to sprouting) x Halberd (intermediate dormancy, moderately tolerant to preharvest sprouting) was grown in replicated experiments and ripe grain harvested for assessment of dormancy, measured as a germination index. Consistent differences were observed between the parents in both experiments. For the bulk of the progeny, the germination index fell within a range defined by Cranbrook at the upper and Halberd at the lower end. Significant quantitative trait loci, all contributed by the very susceptible parent, that explained 11%, 9%, and 9% of the phenotypic variation were identified on chromosome arms 2AL, 2DL, and 4AL, respectively. These QTLs offer the opportunity to develop molecular markers for grain dormancy and to develop a better understanding of the mechanisms involved in this trait.

Mapping QTLs for seed dormancy and the Vp1 homologue on chromosome 3A in wheat

“…Aneuploid analyses have detected dormancy effects and therefore implicated QTLs on the short arms of group 3 chromosomes (Mares et al 1996;Flintham et al 1999). However, no QTLs on the short arms of group 3 chromosomes have been described in other studies on PHS tolerance and seed dormancy of wheat using molecular markers Roy et al 1999;Zanetti et al 2000;Mares and Mrva 2001;Groos et al 2002). Recently comparative mapping across wheat and barley has demonstrated the possibility of a homoeologous relationship between the seed dormancy QTL on chromosome 4AL and the barley SD4 gene (Kato et al 2001).…”

“…Dormancy is generally expressed as a quantitative trait governed by many genes, and in a few cases these genes have been mapped to specific chromosome regions. As a result of the progress with molecular approaches, DNA markers have made it possible to identify individual genetic factors controlling such complex traits as seed dormancy, and several genes or chromosomal regions affecting dormancy have been identified in wheat genomes by means of molecular markers Flintham et al 1999;Roy et al 1999;Zanetti et al 2000;Kato et al 2001;Mares and Mrva 2001;Groos et al 2002).…”

Tam ve Kısıtlı Sulama Uygulamalarının Fasulye (Phaseolus vulgaris L.) Çeşitlerinde Tohum Çimlenmesi ve Fide Gelişimine Etkisi

“…formülüyle hesaplanmıştır (Mares and Mrva, 2001 İncelenen özelliklere ait veriler JMP istatistik programı kullanılarak analiz edilmiş, ortalamaların karşılaştırılması LSD testine göre yapılmıştır.…”

Genotype-based Stability of Dough Quality in Wheat from Different Growth Environments

“…The attribute of sprouting is considered to present a problem only if the environmental factor of rain at harvest is present. The effect of genotype is very important for this attribute because breeders have been able to provide genetic tolerance to the effects of rain at harvest especially for red wheats (Ross & Bettge, 2009;Mares & Mrva, 2001). In this case, there is strong interaction between genotype and environment ('G x E') (Ross & Bettge, 2009;Wrigley & Batey, 2003).…”

“…Heat stress (a few days of >35 o C) during grain filling has been reported to cause dough weakness in the resulting grain (Corbellini, 1998;Blumenthal, 1995). In addition, some genotypes have been reported to be more tolerant than others to the dough-weakening effects of heat stress (Blumenthal, 1995); this example of genotype-based tolerance (G x e) is presumably similar in principle to the well-established tolerance of sprout-resistant varieties to rain at harvest (Mares & Mrva, 2001). …”