A molecular marker linked to the mollis gene conferring soft-seediness for marker-assisted selection applicable to a wide range of crosses in lupin (Lupinus angustifolius L.) breeding

Abstract

To broaden the gene pool of domesticated commercial cultivars of narrow-leafed lupin (Lupinus angustifolius L.), wild accessions are used as parents in crossing in lupin breeding. Among the progenies from wild × domesticated (W × D) crosses, the soft-seediness gene mollis is the most difficult domestication gene to be selected by conventional breeding methods, where molecular marker-assisted selection (MAS) is highly desirable. MAS in plant breeding requires markers to be cost-effective and high-throughput, and be applicable to a wide range of crosses in a breeding program. In this study, representative plants from an F8 recombinant inbred line (RIL) population derived from a W × D cross, together with four cultivars and four wild types, were used in DNA fingerprinting by microsatellite-anchored fragment length polymorphisms (MFLP). Two co-dominant MFLP polymorphisms were identified as candidate markers linked to the mollis gene, and one of the candidate markers was selected and converted into a co-dominant, sequence-specific PCR marker. This marker, designated MoLi, showed a perfect match with phenotypes of seed coat permeability on a segregating population consisting of 115 F8 RILs, confirming the close genetic linkage to the mollis gene. Validation tests showed that the banding pattern of marker MoLi is consistent with all the 25 historical and current commercial cultivars released in Australia, and is consistent with mollis genotypes in 119 of the 125 accessions in the Australian L. angustifolius core collection. Marker MoLi provides a cost-effective way to select the mollis gene in a wide range of W × D crosses in lupin breeding.