Genetic influences on the split seed disorder in Lupinus angustifolius L.

Abstract

During an investigation of the disorder known as split seed in narrow-leafed lupins (L. angustifolius) studies were made on an F₂ population from a cross between the 'bitter' cultivar New Zealand Blue and the 'sweet' cultivar Uniwhite. In a situation where the split seed problem occurred, the presence of the gene for low alkaloid (iucundus) in the homozygous state lowered the proportion of normal seeds from 78.5 to 10.9%, and the non-shedding phenotypes (tardus), in the absence of iucundus, showed reduction of normal seed from 81.8% to 62.4%.

Additional experiments with a wider range of genotypes verified the invoivement of the iucundus gene and showed that the Ku gene for earlier flowering could provide a degree of escape from the disorder. The split seed relationship with iucundus and tardus showed differences in expression at one site, which indicated a difference in their mechanism of action at least in the production of severely deformed or shrivelled seed.