Mapping quantitative trait loci for seedling vigour and development in sunflower (Helianthus annuus L.) using recombinant inbred line population.

The ability of seeds to germinate and establish seedlings in a predictable manner under a range of conditions has a direct contribution to the economic success of commercial crops, and should therefore be considered in plant breeding programs. Quantitative trait loci (QTLs) implicated in seedling vigour and development of sunflower were investigated using a population of recombinant inbred lines (RILs) developed through single-seed descent from the cross 'PAC2 x RHA266'. The experiments were conducted in completely randomized design with three replications. Different traits associated with germination, seedling vigour, early growth and development were studied. Analysis of variance for all studied traits revealed significant differences (P<0.01) among RILs and their parents. A large genetic variation and transgressive segregation was observed for all the studied traits. QTL-mapping was performed using a high-density simple sequence repeat/amplified fragment length polymorphism (SSR/AFLP) linkage map and several QTLs associated with the studied traits were identified. The percentage of phenotypic variation explained by individual QTLs ranged from 5.4% to 35.7%. Based on overlapping support intervals, the co-location of QTLs for all ten traits was determined. QTLs controlling most of the traits were overlapped on different linkage groups, which was in accordance with the phenotypic correlation results among the traits. Although the detected regions need to be fine-mapped to dissect the genes underlying QTLs, the information obtained could help sunflower breeders in marker-assisted breeding programs for developmental traits.