Development of a co-dominant DNA marker tightly linked to gene tardus conferring reduced pod shattering in narrow-leafed lupin (Lupinus angustifolius L.)

The reduced pod shattering gene tardus is one of the most important domestication genes in narrow-leafed lupin (Lupinus angustifolius L.). In development of a molecular marker linked to the tardus gene, we incorporated the concept of marker validation during the initial candidate marker identification stage. Four dominant microsatellite-anchored fragment length polymorphism (MFLP) markers were identified as candidate markers based on their banding patterns in an F-8 recombination inbred line (RIL) population. One specific marker best correlating with phenotypes in the representative germplasm was selected and converted to a simple PCR-based marker. This established marker, designated as "TaLi", is located at a distance of 1.4 cM from the tardus gene. DNA sequencing revealed six insertion/deletion sites between the non-shattering marker allele and the shattering marker allele. Validation of marker TaLi on 25 domesticated commercial cultivars and 125 accessions of the lupin core collection found a 94% marker and tardus phenotype match. Marker TaLi is the first simple PCR-based marker that can be widely used for non-shattering pod selection in narrow-leafed lupin breeding program.