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R.N. LESTER and M.-C. DAUNAY
thum or S. incanum (ISSHIKI et al. 1994, SAKATA and LESTER 1994, KARIHALOO and
GOTTLIEB 1995, MACE et al 1999). Therefore all of the domesticated and weedy Asian
forms of S. melongena may be treated as a single species.
The discrepancy between great morphological diversity, especially in fruit characters,
yet low diversity in molecular markers, is particularly obvious amongst the cultivars of
S. melongena, both primitive and advanced. The wild ancestor is fairly prickly and
has spherical fruits about 2.5 cm diameter, pale green with darker green stripes or
reticulations when immature, ripening directly to orange yellow. The primitive cultivars
are less prickly, and have larger spherical or ovoid fruits that may be white when
immature, whereas more advanced cultivars have few or no prickles and have much
larger fruits of many shapes, from depressed spherical through obovoid to very long
and serpentine, and of many colours when immature, from green to white to pink to
violet to almost black, and patterned or not. The fruit weights range from a few grams
to a few kilograms. Although primitive S. melongena is fairly similar in morphology
and in most DNA and isozyme analyses to some African species, especially S. incanum
or even S. lichtensteinii, there are some clear differences in several molecular
markers, such as the Sal I pattern from chloroplast DNA analyses (SAKATA and
LESTER 1994). Altogether these various data indicate that from the several species
that evolved in Africa, one, which was probably S. incanum, gave rise to a distinct
species which spread to South-East Asia as the wild ancestor of S. melongena
(LESTER and HASAN 1991). This may be called S. cumingii Dunal as a distinct morphological
species, although plant breeders may include it within the same biological
species as S. melongena. This taxon is known from areas in and around Vietnam,
probably even as a truly wild plant of primary vegetation. It seems that from this
rather small gene pool were produced the domesticated forms of S. melongena,
which developed great morphological diversity but relatively little diversity in molecular
markers (DAUNAY et al. 2001b). Mapping the chromosomes with molecular markers
has therefore necessitated a cross between S. melongena and S. linnaeanum, a
rather distant South African relative (DAUNAY et al. 2001b, DOGANLAR et al. 2002a).
3. Solanum macrocarpon L. – Gboma Eggplant
Solanum macrocarpon (classified in Solanum subgenus Leptostemonum section
Melongena series Macrocarpa Bitter) is cultivated widely throughout tropical Africa,
especially in the more humid regions. The glabrous leaves are a very important
green vegetable, cooked like spinach, and the large fruits are cooked in stews with
meat and other vegetables (SCHIPPERS 2000). There is much diversity in both leaves
and fruits. The fruits are 3-12 cm in diameter, spherical or depressed spherical, usually
green, whitish or purplish or with lighter markings when ready for eating, but at
physiological ripeness they turn yellow to orange or brown, and the surface may
crack (DAUNAY et al. 2001a, plate IX, 3). The calyx is very large. Many cultivars are
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