Identification of quantitative trait loci (QTLs) influencing early vigour, height, flowering date, and seed size and their implications for breeding of narrow-leafed lupin (Lupinus angustifolius L.)

We report the first quantitative trait loci (QTL) mapped in an F8 recombinant inbred line (RIL) population of Lupinus angustifolius. Traits mapped were early vigour, days to flowering, height at maturity, and seed size. Twenty-two QTLs were found, located on 13 linkage groups, with alleles beneficial to the crop contributed by both parents. Early vigour was controlled by 8 QTLs on 7 linkage groups. Time to flowering was controlled by 10 QTLs and the height at maturity was found to be under the control of 4 QTLs. Seed size was linked to 2 QTLs. A region linked to the Ku gene that promotes early flowering by removal of the vernalisation requirement appeared to play a role in all 4 traits. The gene mollis controlling soft-seededness appeared to also be linked to early vigour, and iucundis controlling alkaloid production was linked to seed size. Five pairs of QTLs were found to be involved in epistasis, 2 of these having an effect on early vigour and another 3 influencing the time to opening of the first florets. Variation explained for each trait ranged from 28% for seed size, to 88% for days to flowering. We showed that it was possible to use these data to predict genotypes of superior progeny for these traits under Mediterranean conditions. QTL regions were compared on a second published linkage map and regions of conserved synteny with the model legume Medicago truncatula highlighted.