Studies on induced auto-octoploid and its implication in the origin of tetraploid Solarium villosum of the Solarium nigrum complex

Abstract

Auto-octoploidy as confirmed from a somatic chromosome count of 2n = 96 was induced for the first time in Solarium vlllosum, a member of the Solanum nigrum complex. Chromosome doubling helped in assessing the origin/evolution of the tetraploid S. villosum. The average meiotic configuration was 3.80 I + 43.30 II + 0.40 III and 1.10 IV against 24 bivalents in the control. Meiotic abnormalities consisted of laggards, bridges, unequal separation and polysporads all of which adversely affected pollen fertility. The presence of tetravalents and meiotic abnormalities in the octoploid confirmed the natural tetraploid origin of S. villosum and the true genome donor was untraceable or disappeared at an early stage of evolution.