A Chloroplast DNA Phylogeny of Solanum Section Lasiocarpa

Abstract

Solanum section Lasiocarpa includes about a dozen species with a center of diversity in the New World tropics. Solanum lasiocarpum and S. repandum (sometimes considered to be conspecific as S. ferox) have an Old World distribution in Asia and the Pacific Islands. Several species in this section produce edible fruits, and two, the lulo or naranjilla (S. quitoense) and the cocona (S. sessiliflorum) are cultivated commercially. Phylogenetic relationships in Solanum section Lasiocarpa were investigated using sequence data from the chloroplast trnT-trnL spacer, the trnL-trnF spacer, and the trnL gene, including the trnL intron. Sampling included 24 accessions from section Lasiocarpa and 14 accesssions of other Solanum species as outgroups. All species considered to belong to section Lasiocarpa by previous authors were examined with the exception of the recently described S. atheniae. Solanum robustum and S. stagnate, sometimes considered to belong to section Lasiocarpa, are excluded from the group on the basis of the trn data. The remaining species in the section form a monophyletic group, with three well-supported clades within it: S. hirtum, S. pectinatum-sessiliflorum-stramonifolium, and the remainder of the species in the section. Sequences of S. lasiocarpum and S. repandum are extremely similar, and these two Asian taxa cluster with the New World S. candidum and S. pseudolulo on the trn trees.