The ra locus and legumin synthesis in Pisum sativum

Cellulose acetate electrophoresis has been used to resolve the storage proteins of peas into their constituent groups. Comparisons of 171 randomly chosen genotypes representing primitive forms, subspecies, and cultivars of peas, of seven near-isogenic lines for found and wrinkled and of two F2 populations have shown that wrinkled seed has a lower proportion of legumin than round seed. The extent of the reduction varies with the background genotype; some of the wrinkled forms has less than one-third as much legumin as their isogenic round forms. This effect of the ra locus on storage protein composition provides the first example in peas of a mutant analogous to the op 2 and fl 2 mutants in maize. Sodium dodecyl sulphate polyacrylamide gel electrophoresis was used to discriminate the 40 kdalton (alpha subunits) of legumin. On the basis of the data obtained from F2 populations derived from genotypes with distinct alpha subunit patterns, it was shown that the structural genes for the alpha subunit polypeptides of legumin are on chromosome 7, and closely linked to the ra locus.