2006 Volume 8 Issue 4 Pages 171-176
Chromosome composition in interspecific somatic hybrids of Oryza species was investigated by genomic in situ hybridization (GISH). Four hybrids between Oryza sativa (AA) and γ-ray treated (0, 9.7, 19.4 and 48.6 Gy) O. punctata (BBCC) were obtained by protoplast fusion. Reduction in the chromosome number was observed in different hybrid plants treated with increasing doses of γ-rays. One of the results suggested a reduction in the number of A genomic chromosomes in one of the hybrids. When increasing doses of γ-rays were applied, the B and C genomic chromosomes were hardly distinguishable, presumably due to the formation of novel chromosome composition derived from the B and C genomes of O. punctata. We suggest that the novel chromosome chimeras were generated by γ-ray-induced chromosomal breaks, followed by rearrangements during the repair process, leading to the fusion of the genomic segments in O. punctata.
