Inclusion of Tomato in the Genus Solanum as "Solanum lycopersicum" is Evident from Phylogenetic Studies

As DNA sequence data were rapidly accumulated in the last decade, the intense debate on the position of the genus "Lycopersicon" with respect to "Solanum" was recently settled. In this review, we focus on chloroplast DNA restriction fragment length polymorphism (cpRFLP) analysis and molecular phylogenetic study of the chloroplast-encoded NADH dehydrogenase (ndhF) gene of numerous Solanaceae family members including tomato, Solanum lycopersicum (formerly Lycopersicon esculentum). Both studies revealed that S. lycopersicum is clearly included in the large genus Solanum, which includes potato (S. tuberosum) and eggplant (S. melongena). All cpRFLP and different algorithms in ndhF phylogenetic analysis classified S. lycopersicum into the same clade as S. tuberosum. Comparative genome analysis using a high-density genetic linkage map of S. lycopersicum and S. tuberosum indicated that the chromosome structure is highly conserved between the two species. These recent studies indicated that tomato and potato are phylogenetically close and share a recent common ancestor.