Cold and Disease Resistance of Somatic Hybrids between Tomato (Lycopersicon esculentum) and L. peruvianum.

Cotyledon mesophyll protoplasts of tomato 'Ponderosa' were fused with mesophyll protoplasts from true leaves of L. peruvianum, using polyethyleneglycol (PEG) solution and the fusion products cultured in vitro.Somatic hybrids were selected by morphological characteristics of shoots which differentiated on the calli.Ribosomal DNA of the selected plants was analysed and four plants were confirmed to be somatic hybrids.Pollen viabilities of four somatic hybrids were 78.3, 62.2, 60.2, and 36.2%,respectively; the hybrids were all self-fertile.The seedlings of tomato 'Ponderosa', L. peruvianum, and the offsprings of two somatic hybrids were used in growth analysis under low temperature condition.Relative growth rates of the somatic hybrids under low temperature regimen were less than that of L. peruvianum but greater than that of 'Ponderosa'.This investigation demonstrated that the charactor of cold tolerance was introduced from L. peruvianum to the somatic hybrids.The offsprings of the somatic hybrids also showed resistance to tobacco mosaic virus and tomato spotted wilt virus.緒