Successful first and second backcrosses of S-nigrum (plus) S-tuberosum somatic hybrids with both Solanum parents

Somatic hybrids of Solanum nigrum (+) 2 x potato were successfully crossed with S. nigrum and with potato. First and second backcross progeny with S. nigrum could easily be obtained. One of the BC1 genotypes was already self- fertile. Backcrosses with potato had a much lower success rate. Only pollin ations with tetraploid potato resulted in seed-containing berries, Two BC1 genotypes were obtained after 4362 pollinations from which 505 ovules were cultured. The first BC1 genotype grew vigorously in vitro and in the greenh ouse and flowered abundantly. The second BC1 showed many abnormalities and dropped its flowers before anthesis. The first BC1 was again crossed with t etraploid potato and in this generation also the success rate was low. Over 5000 pollinations resulted in 1750 berries from which over 3000 ovules wer e obtained. Twelve plants germinated from these ovules and they were not as vigorous in vitro and in vivo as the BC1 parent. Some of the BC2 genotypes were used for further backcrosses but no BC3 plants were obtained. BC1 and BC3 genotypes that resulted from the backcross program with potato were te sted for resistance to Phytophthora infestans. The BC1 genotype was as resi stant as the S. nigrum fusion parent, but among the eight BC2 genotypes sco red six were resistant, whereas two genotypes showing lesions were suscepti ble.