Comparative Analysis Of Genomes With Repetitive Sequences Between Cultivated And Wild Rice

1. Genomic in situ hybridization (GISH) was applied to somatic chromosomes preparations of Oryza sativa(AA), O. punctata(BB) and O. officinalsi(CC) with genomic DNA from O.sativa as probes, and to somatic chromosomes preparations of O. punctata(BB) and O. officinalis(CC) with genomic DNA from O. punctata. It was obvious that there are close relationship between A, B and C genomes. The results showed the relationship between A and C genome is the closest, and that of between B and C genome is distant.2. Fluorescence in situ hybridization procedure was applied to somatic chromosomes preparations of O. sativa, and O. officinalis with the C₀t-1DNA from O. sativa , O. punctata, O. officinalis .There were the similar C₀t-1DNA singal bands in the homologous chromosomes and we made karyotye analysis of O. sativa, O. punctata,and O. officinalis according to the C₀t-1DNA signal bands. Comparison of C₀t-1DNA fluorescence intensity on the chromosomes of A, B and C genome and analysis of C₀t-1DNA signal bands of these genomes in the chromosomes of O. officinalis, we also found out that the relationship between A and C genome is closer than B and C genome .The telomere region have the conservative C₀t-1DNA singal bands through analysing the bands of those three genomes. However, the repetitve sequences in the region of centromere, close centromere and heterochromosomes have more fast speed of evolution than the telomere region. In addition, acorrding to the conformation of chromosomes and the repetitve sequences signal bands in chromosomes, we got the karyotype of O.officinalis through pairing homologous chromosomes and analysed the karyotype of O. officinali. The method which based on the genomic element can siganificantly enhance the veracity and reliability of karyotype analysis.3. Using the total genomic DNA of O. punctata as the probe and 16-fold unlabeled total genomic DNA of O. sativa as blocking., fluorescence in situ hybridization procedure was applied to somatic chromosomes preparations of O.schweinfurthiana and fluorescence in situ hybridization was applied to somatic chromosomes preparations of O.schweinf urthiana with the C₀t-1DNA from O. punctata as the probe. These research were supposed to distinguish B and C genome in the O.schweinfurthiana.The result demonstrated that the most part of chromosome was blocked by the high density unlabelled total genomic DNA, except the region of centromere. It showed that the squence of centromere region had faster envolutional speed than other parts of chromosome in the homologous species.4. Through fluorescence in situ hybridization procedure was applied to somatic chromosomes preparations of O.schweinf urthiana and O. punctata with total genomic DNA and the C₀t-1DNA as the probe from B genome, the analysis of the sequence content and karyotype variation in the evolution process from diploid to allopolyploid reavaled that the sizes of B genome and C genome in O.schweinf urthiana were different from them in diploids which live in nature. Consequently, we deduced that the new cell genetic characteristic and karyotype in plant will be brought by genome repetitve sequences evolution after the process from diploid to allopolyploid. Comparsion of the signal bands in genome of O. punctata and B genome in O.schweinf urthiana showed that B genome and C genome in O.schweinf urthiana affect each other after the process from diploid to allopolyploid.