Comparative analysis of genomes in Oryza sativa, O. officinalis and O. meyeriana with C0t-1 DNA and genomic DNA of cultivated rice

Abstract

Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) were applied to somatic chromosome preparations of Oryza sativa, O. officinalis/ and O. meyeriana with labeled probes of C₀t-1 DNA and genomic DNA from cultivated rice. The coverage percentage (%) and size (Mb) of C₀t-1 DNA in O. sativa, O. officinalis and O. meyeriana were 47.1±0.16, 38.61±0.13, 44.38±0.13 and 212.33±1.21, 269.42±0.89, 532.56±1.68, respectively. The coverage percentage and size of probe signals with gen omic DNA from O. sativa in O. officinalis and O. meyeriana were 91.0%, 93.6% and 634 Mb, 1 123 Mb respectively, in which there were 365 and 591 Mb in O. officinalis and O. meyeriana which came from O. sativa genomic DNA not from repetitive sequences of O. sativa, and the uncovered genome size in O. officinalis and O. meyeriana was 64 and 78 Mb, respectively. In addition, karyotype analysis was conducted based on the signal bands of C₀t-1 DNA in O. sativa, O. officinalis and O. meyeriana. The results showed that highly and moderately repetitive sequences in Oryza genus were conserved as the functional genes during the evolution process. The repetitive sequence reduplication might be one of the important causes of genome enlargement in O. officinalis and O. meyeriana; the O. officinalis genome enlarged more slowly compared with O. meyeriana. Based on the above results, it is concluded that O. officinalis and O. meyeriana formed by reduplication, rearrangement and gene selective loss during the evolution process.