A major QTL controlling seed dormancy and pre-harvest sprouting/grain α-amylase in two-rowed barley (Hordeum vulgare L.)

Abstract

Barley seed dormancy is controlled by multiple genes that have a strong interaction with the environment. Lack of adequate dormancy results in pre-harvest sprouting in the field under wet weather conditions. On the other hand, too much dormancy has a detrimental effect in the malting house. There is only a very 'narrow window' of dormancy for malting barley. Harrington barley, which has been a dominant malting variety in the international market and widely used in Australia barley breeding programs, is highly susceptible to pre-harvest sprouting. A doubled haploid (DH) population derived from a cross of Chebec/Harrington was used to search for molecular markers linked with seed dormancy and pre-harvest sprouting. One major quantitative trait locus (QTL) was identified to control pre-harvest sprouting measured by α-amylase activity in barley grains, and could explain >70% of the phenotypic variation. This QTL was located on chromosome 5HL and flanked by restriction fragment length polymorphism (RFLP) marker CDO506 and simple sequence repeat (SSR) marker GMS1. The SSR marker (GMS1) linked with this QTL was further validated in a Stirling/Harrington DH population. A minor QTL on chromosome 2H accounted for 8% of phenotypic variation. Two QTLs for seed dormancy were located on chromosomes 2H and 5HL. The major QTL for dormancy coincided with the QTL for pre-harvest sprouting at chromosome 5HL and explained 61% of phenotypic variation. Since the presence of the Harrington allele at this locus favoured not only pre-harvest sprouting, but also increased malting extract, diastatic power, α-amylase, and free amino acid nitrogen, development of high malting quality varieties with pre-harvest sprouting tolerance would appear to be difficult.

A major QTL associated with preharvest sprouting in rapeseed (Brassica napus L.)

“…QTL analysis of PHS as measured by AA revealed a major effect QTL near the telomere of chromosome 5HL and a minor effect QTL on chromosome 2H (Li et al 2003). However, QTLs for seed dormancy have been mapped to all seven barley chromosomes and few major effect QTLs have been identified in different environments (Gao et al 2003;Han et al 1999;Hori et al 2007;Li et al 2003;Prada et al 2004;Romagosa et al 1999;Ullrich et al 1993). Recently, a strong gene related to dormancy was detected within the centromeric region of chromosome 6H in a barley mutant (Prada et al 2005).…”

Effect of Advanced Cycle Breeding on Genetic Gain and Phenotypic Diversity in Barley Breeding Germplasm

“…1). Although there was not intentional selection to increase alpha-amylase activity, the ability to break dormancy quickly in the malthouse is important in malting barley and dormancy has been associated with alpha-amylase levels (Li et al, 2003). The range of values for the elite lines was 50 to 82°DU, and is higher than the 45°DU minimum required by AMBA.…”

Mapping quantitative trait loci controlling pre-harvest sprouting resistance in a red × white seeded spring wheat cross

“…Resistance to pre-harvest sprouting (PHS) is an important trait for both crop production and for seedling survival in wild species (Li et al 2003;Vanhala and Stam 2006). Seed dormancy is defined as the inability of viable seeds to germinate under favourable environmental conditions (Lin et al 1998;Li et al 2004).…”