AFLP mapping of QTLs for in vitro organogenesis traits using recombinant inbred lines in sunflower (Helianthus annuus L.)

Genetic control for two in vitro organogenesis traits, the number of shoots per explant plated (S/E) and the number of shoots per regenerating explant (S/RE), was investigated in 75 recombinant inbred lines (RILs) of sunflowe r and their two parents (PAC-2 and RHA-266). Genetic variability was observ ed among the 75 Rns for the organogenesis traits studied. Some RILs present ed significant differences when compared with the best parental line (RHA-2 66). Genetic gain, in terms of the percentage of the best parent, for 32% o f the selected Rns was significant. A set of 99RILs from the same cross inc luding the 75 mentioned above was screened with 333 AFLP markers and a link age map was constructed based on 264 linked loci. Six putative QTLs for the S/RE (tentatively named osl) and seven QTLs for the S/E (ose) trait were d etected using composite interval mapping. For each trait, the QTLs explaine d 52% (ose) and 67% (osr) of the total phenotypic variance. These results s uggested that additive gene effects predominate in explaining a large propo rtion of the observed genetic variation associated with regeneration abilit y. The coincidental location of QTLs for S/E and S/RE is discussed.