Higher polysomics in 2N = 12 coix taxon: Tetrasomics

Among domesticated population of 2n=12 Coix taxon, a tetrasomic (2n+2; 2n=14) plant was isolated and cytologically studied for the first time. The extra homologous chromosomes in this polysomic seems to have disturbed the behavior of rest of the bivalents during meiosis, to some extent. The majority of the PMCs in the tetrasomic plant showed five bivalents and a quadrivalent, at diakinesis. The various anaphase segregations led to the formation of sub-and super-haploid microspores and male gametes from n-1 (n=5) to n+3 (n=9) chromosomal constitutions. The origin of the polysomic is considered to be through fusion of male and female super-haploid gametes produced by diploid (2n=12) and its aneuploids (2n=11, 2n=13) that occurred in good numbers in the domesticated population. The addition or deletion of the chromosomes, to or from the chromosomal complement, appears to be sustained by these plants and even observed to be showing some amount of fertility.