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 F-8 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 F-8 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.