Schriften zu Genetischen Ressourcen - Genres

R.N. LESTER and M.-C. DAUNAY
sistance), and as it becomes more domesticated it becomes more acceptable as a
crop and is spread further away from its place of origin (LESTER 1989). Solanum
aethiopicum Kumba Group, which occurs from Burkina Faso to Senegal (LESTER et
al. 1986), seems to be a very good example of a crop that is cultivated almost entirely
outside the natural range of its ancestor, S. anguivi (across Africa from Guinea
to Ethiopia and south to South Africa), and that has lost the function of many of its
genes. So, in order to find disease resistance to breed into S. aethiopicum, S. melongena
and S. macrocarpon, we must look at the many wild African species, in particular
those of sections Melongena and Oliganthes (DAUNAY et al. 1999), many of
them being crossable with one or another of these three cultigens (DAUNAY et al.
1991, 1998).
Conclusions
In this paper we have attempted to introduce the reader to the four main African
vegetable Solanum species, and also to the diversity within each cultigen and its
close wild relatives. We have displayed the different levels of knowledge of each of
these species. We have also emphasised the incongruities between morphological
and molecular diversity both within and between the domesticates and their wild relatives.
This has led us on to conclusions that most of the diversity in domesticates is
due to loss of gene function or genetic control.
VAVILOV (1951) considered whether the genes for characters of domesticates were
present in wild populations of the progenitors as rare recessive alleles which were
then selected during domestication, whereas most others have presumed that the
new traits of the domesticates are due to new or mutated genes with new biochemical
functions (HAWKES 1983). We believe that Vavilov was almost right, in that there
are not new genes but rather the loss of function of various genes of the wild progenitor.
Acknowledgements
We are very grateful to IPK, Gatersleben, which paid for Lester to attend the Mansfeld
Symposium, and to Prof. Jack Hawkes for corrections to this paper.
References
AL-ANI, M.N. (1991): Biosystematic study in the genus Solanum section Oliganthes. -
Ph.D. thesis, Univ. Birmingham, Birmingham, U.K., 283 pp.
BITTER, G. (1923): Solana africana, part IV. - Repert. Sp. nov. 16, 1-320.
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