Cytogenetics of the F₁ of Solanum Gilo×S. Aethiopicum Cross

The F₁ hybrids of Solanum gilo (n = 12) × S. aethiopicum (a = 12) had 24 somatic cbromosomes, were vigorous with 68.5% pollen fertility. They produced 72.3% viable seeds. Close pairing of bivalents with a few unpaired differential segments were noted in F₁. The average chromosome association per cell at diakinesis was 0.12 IV (0–1) + 0.22 III (0–2) + 11.42 II (7–12) + 0.22 1(0–1). Twelve bivalents were recorded in 86% cells. The average chiasma frequency per bivalent was reduced from 1.87 at diplotene to 1.28 at diakinesis. Some bivalents failed to coorient properly at metaphase I plates.At anaphase I, chromatid bridges, fragments and laggards were found, in 23% cells and the rest had normal 12:12 separation. Unequal distribution of chromosomes at metaphase II was noted in 10% cells. One to two micronuclei were observed in 7% cells at pollen tetrad stage. The hybrid sterility is segregational in nature. It is suggested that S. gilo and S. aethiopicum are genetically quite close and their chromosome complements bear high homology in spite of some differentiation through interchange.