Fertile somatic hybrids between Solanum integrifolium and S. sanitwongsei (syn. S. kurzii ) as candidates for bacterial wilt-resistant rootstock of eggplant

Abstract

UV-irradiated cotyledonary protoplasts of Solanum integrifolium and iodoacetamide-treated cotyledonary protoplasts of S. sanitwongsei were electrofused and cultured. Regenerated plants were classified into three groups based on morphology and genomic in situ hybridization data. Morphology of the first group was intermediate between those of parental species. The plants bore fruits with viable seeds and had a chromosome number of 2n=48, the sum of the parental chromosome numbers, suggesting that they were symmetric fusion hybrids. Morphology of the plants in the second group was more S. integrifolium-like than that of the first group, and had two sets of S. integrifolium chromosomes and one set of S. sanitwongsei chromosomes. In contrast, plants in the third group had one set of S. integrifolium chromosomes and two sets of S. sanitwongsei chromosomes. Plants in the second and third groups were less vigorous than those in the first group, and bore few fruits. Electrophoretic analysis of the isozymes shikimate dehydrogenase, isocitrate dehydrogenase, and phosphoglucomutase, as well as random amplified polymorphic DNA analysis, demonstrated that 23 of regenerated plants from the three groups were somatic hybrids. The plants in the first group grew more vigorously than the parental plants and produced more than 5000 seeds per plant. The fertile somatic hybrids obtained in this study may be suitable candidates for eggplant rootstocks. Copyright © 2007 The Japanese Society for Plant Cell and Molecular Biology.