Molecular systematics of Abelmoschus (Malvaceae) and genetic diversity within the cultivated species of this genus based on nuclear ITS and chloroplast rpL16 sequence data

Abstract

The genus Abelmoschus includes several crop plants which are especially important in SE Asia and several African countries. However, the systematic treatment of this genus is difficult, in part because hybridization between different forms seems to be frequent. In this study we present nuclear internal transcribed spacer ITS and chloroplast rpL16 sequences with the aim of reconstructing phylogenetic relationships within Abelmoschus, and its relationship with the genus Hibiscus and other related Malvaceae. Based on our analysis of nuclear ITS and chloroplast rpL16 sequence data, Abelmoschus is resolved as a monophyletic clade. Abelmoschus tetraphyllus is clearly separated from A. manihot but closely related to A. ficulneus and should not be treated as a subspecies of A. manihot. None of the wild species included in this study can be confirmed as an ancestor of A. esculentus or A. caillei. Neither A. esculentus nor A. caillei can be distinguished from each other by the markers used for this study, although the evidence does not exclude the possibility of a hybrid origin of A. caillei involving A. esculentus and an unknown species. The genetic diversity within A. esculentus and A. caillei is low if compared with A. manihot. The evidence presented here does not allow us to draw any conclusions about the geographic origin (Africa vs. Asia) of A. esculentus.