QTL analysis of agronomic traits in barley based on the doubled haploid progeny of two elite North American varieties representing different germplasm groups

A better understanding of the genetics of complex traits, such as yield, ma y be achieved by using molecular tools. This study was conducted to estimat e the number, genome location, effect and allele phase of QTLs determining agronomic traits in the two North American matting barley (Hordeum vulgare L.) quality variety standards. Using a doubled haploid population of 140 li nes from the cross of two-rowed Harrington x sixrowed Morex, agronomic phen otypic data sets from nine environments, and a 107-marker linkage map, we p erformed QTL analyses using simple interval mapping and simplified composit e interval mapping procedures. Thirty-five QTLs were associated, either acr oss environments or in individual environments, with five grain and agronom ic traits (yield, kernel plumpness, test weight, heading date, and plant he ight). Significant QTL x environment interaction was detected for all trait s. These interactions resulted from both changes in the magnitude of respon se and changes in the sign of the allelic effect. QTLs for multiple traits were coincident. The vrs1 locus on chromosome 2 (2H), which determines infl orescence row type, was coincident with the largest-effect QTL determining four traits (yield, kernel plumpness, test weight, and plant height). QTL a nalyses were also conducted separately for each sub-population (six-rowed a nd two-rowed). Seven new QTLs were detected in the sub-populations. Positiv e transgressive segregants were found for all traits, but they were more pr evalent in the six-rowed sub-population. QTL analysis should be useful for identifying candidate genes and introgressing favorable alleles between ger mplasm groups.