Meiotic Studies in Species-hybrids of the Solanum nigrum L. Complex

Abstract

Morphology and meiosis of S. retroflexum (2n=48) and S. nodiflorum ssp. nutans (2n=24), and of their hybrids (F₁, 2n=36) and synthetic polyploids (C₂, 2n=72) were studied in detail. The hybrids showed irregular meiosis, they were sterile and did not set fruit. The synthetic polyploids showed mostly normal meiosis, the pollen fertility was much increased. They set fruit and seed spontaneously. From these studies, it is suspected that polyploidy and structural differences of chromosomes are the main factors in genetic isolation of the species.
On the basis of chromosome behaviour of the parents S. retroflexum, S. nodiflorum ssp. nutans, hybrids and synthetic polyploids, at meiosis, their genomic constitution is represented as AABB, A'A', AA'B and AAA'A'BB, respectively.