GENETIC LOCALIZATION OF TRANSFORMATION COMPETENCE IN DIPLOID POTATO

In the course of improving diploid potato genotypes for transformation ability, selection for specific components affecting regeneration and transformation was carried out. From a segregating population between two good regenerating clones a selection was made to yield an optimal well-transforming and fertile genotype J92-6400-A16. This plant yield ed predominantly diploid transformants and was heterozygous for the ge ne R1, conferring resistance to Phytophthora infestans. The speed of, and competence for, regeneration and transformation on both sides of t he stem explant were improved. A competence factor for tranformation w as found to be linked with the R1 locus and a molecular marker on chro mosome 5. The male fertility of transformants was frequently decreased to a great extent, whereas female fertility was not so markedly affec ted.