| dc.description.abstract | The perception of African nightshades (
Solanum
section
Solanum
) as “healthy” foods, supported by documentation of their high nutri-
tional and medicinal benefits, has led to a sudden and steady upsurge in their consumption, demand and monetary value in Africa
and
most parts of South-East Asia. However, due to very low leaf yields, production of these vegetables remains on small-scales, re
sulting in
acute shortages and escalating prices, especially in urban areas. Apart from local variants or landraces selected in some regio
ns where
these plants are utilized as food and/or me
dicinal plants, there are no improved cultivars developed through conventional plant
breeding
techniques. Species belonging to this section, generally referred to as “
Solanum nigrum
-complex” are predominantly autogamous, favour-
ing production of many small fruits and seeds, which compete with leaves for photosynthates.
S
.
nigrum
-complex constitutes a polyploid
series, with diploid (2
n
=2
x
=24), tetraploid (2
n
=4
x
=48), hexaploid (2
n
=6
x
=72) and rarely, octoploid (2
n
=8
x
=96) species, a trait that can be
exploited for cultivar development. This review outlines the possi
ble evolutionary mechanisms and modes of origin of the polypl
oids,
breeding strategies to produce heteroploids such as triploid (2
x
=3
x
=36), pentaploid (2
n
=5
x
=60) and heptaploid (2
n
=7
x
=84) from existing
or induced polyploids and envisaged advantageous properties of the novel polyploids or heteroploids over their wild-type progen
itors.
With few exceptions, heteroploidy is known to cause sterility or
highly reduced fertility of both pollen and ovules. The Africa
n nightshade
heteroploid series would putatively be male- and female-sterile, thus eliminating fruit- and seed-set and enhancing leaf produc
tivity. | en_US |
