Quantitative trait loci controlling kernel discoloration in barley (Hordeum vulgare L.)

Abstract

Abstract. 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.

Genetic Impacts of the Hull on Barley Grain Quality

“…Higher levels of correlation were observed between the grain colour components, in particular L and b values (Table II). While there was a low correlation between the colour components for the population used in this study, these values were similar to those reported by Li et al 25 . Li et al 25 presented data on the correlation between the three colour components across a number of populations.…”

“…While there was a low correlation between the colour components for the population used in this study, these values were similar to those reported by Li et al 25 . Li et al 25 presented data on the correlation between the three colour components across a number of populations. The level of hull had a positive correlation with screenings, and a negative relationship with retention in 2002 while the opposite relationship occurred in 2003 (Table II).…”

“…Markers on 4 (4H), namely Ebmac0906 and Ebmac310 were iden tified for hull thickness (Patty allele) and the red-green colour value ("a"). These have also been identified by Li et al 25 for blue-yellow in a single population with blue aleurone. Further this region has been associated with KD and FHB resistance in studies from North America.…”

“…The marker (HVM54) identified on 2 (2H) for hull content was also associated with KD (L). This marker was also identified by Li et al 25 , while Mesfin et al 27 and De la Pena et al 29 associated it with FHB resistance. These results suggest that a decrease in hull thickness could impact on the fungal levels on the seed.…”

“…Further this region has been associated with KD and FHB resistance in studies from North America. The results for KD colour characteristics reported in this study, as well as the work reported by Li et al 25 were measured using a colour meter while the work carried out in North America used visual assessment 7,29 . Despite the potential variability between measurements, common markers have been identified.…”