Development of a DNA marker tightly linked to low-alkaloid gene iucundus in narrow-leafed lupin (Lupinus angustifolius L.) for marker-assisted selection

Narrow-leafed lupin (Lupinus angustilolius L.) is a grain legume of exceptionally high nutritive value and much versatile food and animal feed around the world. The development of lupin as a modern crop was limited by its high concentration of alkaloids. Progress in breeding necessitates a better understanding of the genetics underlying the trait – low-alkaloid level (sweet). Marker-assisted selection would allow a better targeting of the desired genes. The microsatellite-anchored fragment length polymorphism (MFLP) fingerprinting technology was applied to an F8 recombination inbred line (RIL) population to identify and select candidate markers linked to the low-alkaloid gene iucundus. Four MFLP markers were identified as candidate markers based on their banding patterns in the F8 RIL population. One of these candidate markers showing the best correlation with phenotypes in the representative germplasm was selected and successfully converted into a simple PCR-based co-dominant marker, named IucLi. This established marker IucLi is 0.9 cM away from the sweet (low-alkaloid) gene iucundus. The accuracy between marker genotype and phenotype is 100% in the common 25 cultivars and 86.4% among the 125 accessions of narrow-leafed lupin core collection. Marker IucLi is being used in narrow-leafed lupin breeding for selection of ‘sweet’ individuals. The marker is also used to develop near-isogenic lines to further characterise and fine mapping the iucundus locus.