Protoplast fusion between Lycopersicon esculentum and L-peruvianum-complex:: somatic embryogenesis, plant regeneration and morphology

Somatic hybrids were obtained by polyethylene glycol fusion of cotyledon protoplasts of Lycopersicon esculentum Mill. cv. Kyoryokutoko treated with iodoacetamide (IOA) and suspension-culture-derived protoplasts of L. peruvianum (PI27O435) or L. chilense (PI128652). The hybrids were selected by a multiple-step selection procedure relying on the different colors of the fusion partners. IOA treatment of cotyledon protoplasts, and the use of a culture medium which only allowed cotyledon protoplasts to regenerate. The somatic embryos were derived from greenish calli that formed from the fusion mixtures, developed progressively through the globular, heart, and torpedo stages, and finally formed complete plantlets. The excised torpedo-stage embryos could be propagated on a modified medium. The morphology of the somatic hybrids were intermediate to their donor partners, and chromosome observations indicated that the hybrids were tetraploid, hexaploid. and aneuploid.