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R.N. LESTER and M.-C. DAUNAY
Diversity of African vegetable Solanum Species and its implications
for a better understanding of plant domestication
R.N. LESTER 1 and M.-C. DAUNAY 2
Abstract
The domestication of Solanum vegetables in Africa depended on the development of
agricultural systems and the availability of suitable wild or introduced species. Solanum
aethiopicum (scarlet eggplant) and S. macrocarpon (gboma eggplant) are African,
S. melongena (brinjal eggplant) was introduced from Asia, but its closest relatives
are African, and S. scabrum (one of the black nightshades) was probably domesticated
in Africa. Studies of these eggplants have shown that domestication has
produced a vast increase in morphological diversity of the cultigens compared with
their wild ancestors, yet the diversity in molecular markers has not increased. This
morphological diversity in eggplants and all other domesticated plants is mostly attributable
to so-called recessive genes, and can be explained by the loss of existing
gene function or regulation rather than being due to new genes. This paradigm may
also help explain some of Vavilov’s hypotheses, and has practical implications for
plant breeding, taxonomy and core collections in genebanks.
Introduction
Over 100 species of Solanum are indigenous to Africa, and several of these have
been developed as vegetables there. This paper discusses the diversity of these domesticates
and their close relatives, considers their evolution, and attempts to explain
it.
Relatively little is certain about the development of agriculture and the domestication
of crop plants in Tropical Africa, which is the vast area between the Sahara Desert on
the Tropic of Cancer and the Kalahari Desert on the tropic of Capricorn. It is generally
accepted that agricultural systems based on grain crops in the Fertile Crescent in
Western Asia were taken to Egypt and Ethiopia, providing the bases of the great civi-
1 Birmingham University Botanic Garden
58 Edgbaston Park Road
Birmingham, B15 2RT, UK
2 INRA
Unité de Génétique et Amélioration des Fruits et Légumes
BP 94
84143 Montfavet cedex, France
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