QTLs and their interaction determining different heading dates of barley in Australia and China

Heading date is a major determinant of the regional and seasonal adaptation of barley varieties. The dogma is that introduced germplasm is more likely to be adapted if it is derived from a similar latitude. However, barley germplasm introduced from similar latitudes of South-East Asia is extremely early heading in the Australian environments and vice versa. A doubled-haploid population from a cross of an Australian barley Galleon and a Japanese barley Haruna Nijo was evaluated for heading date in Australia (Perth, 31°56′S) and China (Wuhan, 30°33′N) under normal autumn sowing, late sowing in the field, and extended-light glasshouse conditions. One major QTL was identified on chromosome 5H under the three conditions in China. The single QTL accounted for up to 50% of phenotypic variation for heading date. The Australian variety contributed to late heading date. Two QTLs on chromosomes 4H and 5H were detected for controlling heading date in Australia. The QTL/QTL interaction contributed up to 35.8% of phenotypic variation for heading date in Australia, which is the major reason for the extremely early heading date of the Japanese variety in the Australian environment. The chromosome 5H QTL was detected at the same chromosomal location when the population was grown in either China or Australia. In both environments the Australian variety contributed to the late heading date. Selection against the Japanese alleles of chromosomes 4H and 5H QTLs could eliminate the extremely early genotype in Australia and selection against the Australian allele of chromosome 5H QTL could eliminate the extremely late genotype in China when Australian and Japanese germplasms are used in the breeding programs

Mapping and QTL analysis of the barley population Tallon × Kaputar

A genetic map of barley with 224 AFLP and 39 simple sequence repeat (SSR) markers was constructed using a doubled haploid (DH) mapping population from a cross between the varieties Tallon and Kaputar. Linkage groups were assigned to individual barley chromosomes using the published map locations of the SSR markers as reference points. This genetic map was used to identify markers with linkage to agronomic, disease, and quality traits in barley. The population, which comprised 65 lines, was tested in a range of environments across Australia. Quantitative trait loci (QTLs) analyses were performed using software packages MapMaker, MapManager, and Qgene. Significant associations with markers were found for several traits. Grain yield showed significant association with regions on chromosomes 2H, 3H, and 5H over a range of sites throughout Australia. Regions on chromosomes 2H and 3H explained 30% and 26% of variation in lodging, respectively. Among quality traits, diastatic power was associated with regions on chromosomes 1H, 2H, and 5H (R2 = 37%). Hot water extract was associated with a region on chromosome 6H and a marker not assigned to a chromosome (R2 = 45%). There were also environment-specific QTLs for the traits analysed. The markers identified here present an opportunity for marker assisted selection of lines for these traits in barley breeding programs

Mapping and QTL analysis of the barley population Chebec x Harrington

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

Mapping and QTL analysis of the barley population Chebec x Harrington

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

Mapping and QTL analysis of the barley population Chebec × Harrington

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