Department of Botany, Aligarh Muslim University, Aligarh
Online published on 25 January, 2012.
A biosystematic study of the S. nigrum complex was undertaken with a view to unravelling the nature of sterility barriers among the species of the S. nigrum complex. In the present investigation S. villosum, S. luteum, tetraploid S. nigrum and S. nodiflorum, which are included in this complex, were selected. The species differ mainly on the basis of fruit colour and chromosome number as shown below:
S. villosum S. luteum S. nigrum S. nodiflorum
Fruit colour Yellow Yellow Orange red Shiny bluish black
Chromosome number (n) 24 24 24 12
Several triploid hybrids were produced by crossing S. villosum, S. luteum and tetraploid S. nigrum with S. nodiflorum. The hybrids were sterile with a variety of meiotic abnormalities. This shows that the three genomes in the triploids are dissimilar with respect to a majority of their chromosomes. It is concluded that the structural differences between the chromosomes of the parents and probably also genetic factors have played a role in breakdown of meiosis, sterility of the hybrids and genetic distinctiveness of S. nodiflorum from S. villosum, S. luteum and tetraploid S. nigrum..
