Cytogenetics of saccharum officinarum L. And 5. Spontaneum L.IV. Chromosome number and meiosisin S. Officinarum XS. Spontaneum hybrids

Abstract

Chromosome numbers and meiosis in 164 interspecific hybrids representing 17 combinations of S. officinarum (2n=80) x S.spontaneum (2n = 54, 56, 61, 63, 64 80, 112, 124 and 128) are reported. Hybrids involving S.spontaneum 2n = 61, 63 and 124 as the pollen parents are reported for the first time.Among 164 Fi hybrids, 155 had the sum of the somatic chromosome number of S. officinarum and gametic number of S. sponlaneum i.e. (2n + n) constitutions. It is inferred that the pistil parent S. officinarum has also transmitted its somatic chromosome numbers to six of the remaining nine hybrids. The transmission of unexpected chromosome numbers by the parental clones to eight of these nine hybrids is explained on the basis of observed cytological irregularities.Except for the rare occurrence of multivalents m few hybrids, bivalent pairing has been predominant and it is inferred that autosyndesis prevails in the hybrids.Based on the chromosome pairing in the interspecific hybrids, it has been assumed that either S. spontaneum was involved in the origin of S. officinarum or both the species had a common ancestry, before following different evolutionary pathways.The significance of the functioning of diploid gametes in S. officinarum to establish new chromosomal balances at different levels of ploidy has been indicated. © 1990 Taylor & Francis Group, LLC.