Search

Barley kernel discoloration (KD) leads to substantial annual loss in value through downgrading and discounting of malting barley. KD is a difficult trait to introgress into elite varieties as it is controlled by multiple genes and strongly influenced by environment and maturity. As the first step towards marker assisted selection for KD tolerance, we mapped quantitative trait loci (QTLs) controlling KD measured by grain brightness [Minolta L; (Min L)], redness (Min a), and yellowness (Min b) in 7 barley populations. One to 3 QTLs were detected for grain brightness in various populations, and one QTL could account for 5–31% of the phenotypic variation. The QTL located around the centromere region of chromosome 2H was consistently detected in 6 of the 7 populations, explaining up to 28% of the phenotypic variation. In addition, QTLs for grain brightness were most frequently identified on chromosomes 3H and 7H in various populations. Australian varieties Galleon, Chebec, and Sloop contribute an allele to increase grain brightness on chromosome 7H in 3 different populations. A major gene effect was detected for grain redness. One QTL on chromosome 4H explained 54% of the phenotypic variation in the Sloop/Halcyon population, and was associated with the blue aleurone trait. A second QTL was detected on the long arm of chromosome 2H in 3 populations, accounting for 23–47% of the phenotypic variation. The major QTLs for grain yellowness were mapped on chromosomes 2H and 5H. There were strong associations between the QTLs for heading date, grain brightness, and yellowness. The molecular markers linked with the major QTLs should be useful for marker assisted selection for KD. Proceedings of the 11th Australian Agronomy Conference, Geelong, 2003.

A doubled haploid population of 120 individuals was produced from the parents Chebec, an Australian 2-row barley of feed quality with resistance to the cereal cyst nematode, and Harrington, a 2-rowed, Canadian variety of premium malting quality. This paper describes 18 field and laboratory experiments conducted with the population and summarises the traits mapped and analysed. The genomic location of 25 traits and genes is described and marker–trait associations for 5 traits (malt extract, diastatic power, resistance to cereal cyst nematode, early flowering, resistance to pre-harvest sprouting) important to Australian efforts to improve malting barley varieties have been used in practical breeding programs. Detailed maps for these populations are shown in this paper, while a consensus map incorporating these maps and further experiments on the populations are described elsewhere in this issue.

Two populations between the German malting variety Alexis and the Australian malting variety Sloop were constructed, mapped, phenotyped, and subjected to quantitative trait loci analysis. One population consisted of 153 F4-derived recombinant inbred lines and the other of 111 doubled haploid lines. This paper describes 18 field and laboratory experiments conducted with the populations and summarises the traits mapped and analysed. The genetic basis of 5 traits (malt extract, resistance to leaf rust, resistance to powdery mildew, early flowering, plant stature) important to Australian efforts to improve malting barley varieties was elucidated. Detailed maps for these populations are shown in this paper, while a consensus map incorporating these maps and further experiments on the populations are described elsewhere in this issue.