Advanced-backcross QTL analysis in hulless barley: I. Detection of exotic alleles for yield and yield components introgressed from Hordeum vulgare ssp. spontaneum

ABSTRACT: An advanced backcross breeding strategy was used to identify quantitative trait loci (QTLs) associated with yield and yield components in a BC3 population derived from an interspecific cross between six-rowed spring barley (H. vulgare) ‘Azhul’ and wild barley (H. spontaneum) line ‘Spontaneum I’. The result of correlation analysis showed that the grain yield was positively correlated with number of grains per spike, biomass, spike length and chlorophyll content. The linkage map constructed by 170 SSR molecular markers covered a total length of about 1008.7 cM. For seven agronomical characteristics, 25 QTLs were determined. The phenotypic variation explained by individual QTLs ranged from 5.3% to 33.8% and the LOD scores ranged between 3.1 and 9.4. A total of 17 new QTLs were identified, where at six QTLs (35.3%) the exotic introgression caused an improved trait performance. Three QTLs contributed by ‘Spontaneum I’ on chromosomes 1H, 2H and 4H were found to significantly increase chlorophyll content, biomass and spike length, respectively. In conclusion, the results of this study showed that Hordeum spontaneum, the wild progenitor of barley, is a potential source of useful genetic variation for barley breeding programs.