Shedding new light on the origin and spread of the brinjal eggplant (Solanum melongena L.; Solanaceae) and its wild relatives

• While brinjal eggplant (Solanum melongena L.) is the second most important solanaceaous vegetable crop, we lack firm knowledge of its evolutionary relationships. This in turn limits efficient use of crop wild relatives in eggplant improvement. Here, we examine the hypothesis of linear step-wise expansion of the eggplant group from Africa to Asia.
• We use museum collections to generate nuclear and full-plastome data for all species of the eggplant clade. We combine a phylogenomic approach with distribution data to infer a biogeographic scenario for the clade.
• The eggplant clade has Pleistocene origins in northern Africa. Dispersions to tropical Asia gave rise to Solanum insanum, the wild progenitor of the eggplant, and to Africa distinct lineages of widespread and southern-African species. Results suggest that spread of species to southern Africa is recent and was likely facilitated by large mammal herbivores feeding on Solanum fruits (African elephant, impala).
• Rather than a linear ‘Out Of Africa’ sequence, our results are more consistent with an initial event into Asia, and subsequent wide dispersion and differentiation across Africa driven by large mammalian herbivores. Our evolutionary results will impact future work on eggplant domestication and use of wild relatives in breeding of this increasingly important solanaceous crop.