Cytogenetical studies in Phaseolus. I. Aulotetraploid Phastolus aureus × tetraploid species of Phaseolus and the back-crosses

The hybrid (2n=44) and back-cross plants of the cross between an auto-tetraploid (2n=44) of a widely cultivated legume, Phaseolus aureus and an autotetraploid species of Phaseolus (2n=44) were studied. The hybrid resembled the parents in its morphological characters. Cytological studies in the Fx at pachytene and metaphase I stages revealed autosyndesis in F₁ and also intra-genomic homology in 4x Phaseolus sp. The meiosis of the polyhaploid of 4x Phaseolus sp. was reconstructed. Chromosome pairing studies in F₁ × 4x Phaseolus sp. plants revealed chromosomal homology between a maximum of eight aureus and 4x Phaseolus sp. chromosomes. The nucleolar chrcmcsome of 4x Phaseolus sp. was not associated with the nucleolus in the F₁ and back-cross plants.