Secondary associations of univalent chromosomes in haploids and hybrids of Gossypium

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Abstract
Secondary associations at metaphase I were analyzed in five genetically different haploids of the allotetraploid G. hirsutum and in the A2D5 hybrid F1 between G. arboreum (A2) and G. raimondii (D5) Eighty-three percent of the associations were allosyndetic of AD chromosomes while 17 percent of the associations were classified as autosyndetic of AA and DD chromosomes. The end-to-end associations were in excess of the end-to-side and side-to-side and their respective frequencies were 75, 14, and 11 percent. Reasons are given why these associations were nonrandom, specific, and allosyndetic. The excess of the AD and end-to-end associations over the other types is taken as an indication of homology and gives additional support to the homoeology between the A and D genomes.