INTROGRESSIVE HYBRIDIZATION OF TOMATOES BY GAMMA-FUSION OF LYCOPERSICON-ESCULENTUM MILL AND LYCOPERSICON-PERUVIANUM VAR DENTATUM DUN PROTOPLASTS

Leaf mesophyll protoplasts of chlorophyll-deficient Lycopersion esculentum Mill. (plastome mutant Pl-alb 1) were fused in a fusion-inducing solution (PEG + Ca2+ + high pH) with mesophyll protoplasts of wild-type Lycopersicon peruvianum var. dentatum Dun. (lines 3767 and 3772) and interspecific nuclear and/or cytoplasmic hybrid plants were regenerated under selective conditions. The selection of hybrid clones was based on the inability of the L. peruvianum protoplasts to divide after gamma pre-irradiation and white colouration of minicalli from protoplasts of the other parent in contrast to that of the hybrid calli. The hybrids were identified on the bases of esterase isozymes spectra, plastid and mitochondrial DNA, mitosis and meiosis, and also leaf, flower and fruit morphology. Field testing of hybrid plants in the course of one vegetation period demonstrated their high viability. All hybrid clones abundantly blossomed and set fruits with abortive seeds.