T-DNA-TAGGED CHROMOSOME-12 IN DONOR LYCOPERSICON-ESCULENTUM X L-PENNELLII IS RETAINED IN ASYMMETRIC SOMATIC HYBRIDS WITH RECIPIENT SOLANUM-LYCOPERSICOIDES

Asymmetric somatic hybrid plants were recovered after fusing irradiate d mesophyll protoplasts of donor Lycopersicon esculentum x L. pennelli i (EP) interspecific hybrid with callus-derived protoplasts of recipie nt Solanum lycopersicoides. EP plant A54 had been previously transform ed by an agrobacterium vector, and the T-DNA insert mapped to the L. e sculentum chromosome 12. The T-DNA insert conferred kanamycin resistan ce to EP that was subsequently used to select cell fusion products and recover asymmetric hybrid plants that retained tagged chromosome 12. Doses of 50- and 100-Gy irradiation promoted the elimination of only a few donor chromosomes. At 200 Gy, the regenerated plants had ploidy l evels higher than tetraploid. However, the T-DNA tagged chromosome 12 was always retained in the asymmetric hybrid plants tested. Likewise, all plants from the 100-Gy series, with the exception of number 160, w ere mixoploid in the root-tip cells. Such mixoploid asymmetric somatic hybrids could be stabilized by inducing adventitious shoots on leaf s trips cultured on shoot regeneration medium containing kanamycin. The asymmetric hybrid plants did not produce viable seed when self-pollina ted or backcrossed to tomato or S. lycopersicoides.