1987/05/01 by A. B. Sapre, D. S. Deshpande · 4 citations
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Plant Disease Resistance and Genetics #Microbial Metabolism and Applications #GABA and Rice Research
paper · doi:10.1093/oxfordjournals.jhered.a110355
Much literature has accumulated on the various aspects of B chromosomes, but their origin continues to puzzle cytologists. Cytological screening of the interspecific hybrids and hybrid derivatives of Coix produced by growing together two allopatric species, C. gigantea (2n = 20) and C. aquatica (2n = 10), revealed that one or two chromosomes from gigantea species (G) showed B chromosome-like behavior when incorporated in the aquatica genome (A) through spontaneous hybridization. Among the hybrid derivatives of C. gigantea × aquatica, plants with 2n = 11 chromosomes comprising 10A + 1G and 9A + 2G showed B-like behavior of the G chromosome(s) through meiosis. Had it not been for the fact that 2n = 11 chromosome plants are known to be of hybrid origin they could have been easily mistaken for C. aquatica (2n = 10) plants with B chromosome(s); the latter in reality having come from another species (C. gigantea) through open pollination. Repeated cytological screening of populations comprising interspecific hybrids and hybrid derivatives of Coix have demonstrated how homologous, homoeologous and/or nonhomologous chromosome(s) could flow between the related species and subsequently establish themselves as B chromosomes. In the absence of any direct evidence to the origin of B chromosomes so far, it is concluded that in most populations they possibly could arise through spontaneous hybridization; at least there is evidence to indicate that is so in Coix.