Development of a sequence-specific PCR marker linked to the gene "pauper" conferring low-alkaloids in white lupin (Lupinus albus L.) for marker assisted selection

Seeds and plants of wild type Lupinusalbus are bitter and contain high level of alkaloids.During domestication, at least three genes conferringlow-alkaloid content were identified and incorporatedinto commercial varieties. Australian lupinbreeders exclusively utilize one of these sweetnessgenes, ‘‘pauper’’, in all varieties to prevent possiblebitterness contamination via out-crossing. A crosswas made between a sweet variety Kiev Mutant(containing pauper gene) and a bitter type landraceP27174, and the population was advanced into F8recombinant inbred lines (RILs). Twenty-fourplants representing sweetness and bitterness weresubjected to DNA fingerprinting by the microsatellite-anchored fragment length polymorphism(MFLP) technique. A dominant polymorphism wasdiscovered in an MFLP fingerprint. The MFLPmarker was converted into a co-dominant, sequencespecific,simple PCR-based marker. Linkage analysisby the software program MapManager withmarker score data and alkaloid phenotyping datafrom a segregating population containing 190 F8RILs indicated that the marker is linked to thepauper gene at the genetic distance of 1.4 centi-Morgans (cM). This marker, which is designatedas ‘‘PauperM1’’, is capable of distinguishing thepauper gene from the other two low-alkaloid genesexiguus and nutricius. Validation on germplasmfrom the Australian lupin breeding program showedthat the banding pattern of the marker PauperM1 isconsistent with the alkaloid genotyping on a widerange of domesticated varieties and breeding lines.The PauperM1 marker is now being implementedfor marker assisted selection in the Australian albuslupin breeding program.