Genetic analysis of protoplast regeneration ability in Brassica oleracea

In Brassica oleracea L., plant regeneration from protoplasts is genotype-de pendent and colony formation can be obtained routinely. In order to identif y genes for regenerability, we performed a genetic analysis of the characte ristic in the F-2 generation of a cross between two accessions selected for high and low regenerability. Regeneration frequencies were obtained from p rotoplast culture of 248 individual F-2 plants after 5, 10, and 15 weeks of culture on regeneration medium. Broad-sense heritability estimate was 0.49 2 at the early stage and lower (0.046-0.149) at advanced stages. The freque ncy distribution observed during short-term culture can be explained by two independent loci with duplicate dominant genes controlling regeneration. I n long-term culture, one additional dominant gene can confer regeneration; i.e., three independent loci are responsible for regenerability. The result s suggest that selection for high regeneration response may be efficient at early stages because of the lower environmental influence on the character istic, and because fewer genes are involved at this stage than at advanced stages. The control of regenerability by a few dominant genes facilitates i ncorporation of the trait into breeding material. Molecular markers linked to the genes may assist in the selection of genotypes with high regeneratio n percentage in the future.