| Modern sugarcane cultivar contributes about 70% of sugar and 40% of ethanol production in the world. Stress tolerance of cultivar was considered to be attributed by S.spontaneum, while, knowledge of cytological architecture of this crop is still lack of understanding. With the development of genomic research, it is necessary to analyze the karyotype of S.spontaneum. This study conducted an investigation about S.spontaneum by comparative genomics and molecular cytological methods with sorghum genomic information as reference. The main results are as follows,(1)114 single/low copy BACs were achieved by comparing tetraploid spontaneum BAC library with sorghum sequences, which corresponded to 10 sorghum chromosomes, number 1～114,7 to 16 probes were located on each sorghum chromosome.(2)Protocols for sugarcane BAC-FISH were introduced in this study.27 chromosome-specific cytological markers for S.spontaneum were developed. Whereas, the number of hybridization signals were range from 1 to 7, the intensity of the signals on different chromosomes generated by the same probe were varient. This evidence challenge the widespread recognition of autopolyploidy for S.spontaneum.(3)3 probes(24,66,78) and 4 probes(69,71,73,77)were respectively used to construct physical mapping of chromosome 1 and chromosome 2 for S.spontaneum, providing the foundation for genome sequencing of sugarcane.(4)Homological probe number 14 probe and number 19 probe corresponding to the number 2 and number 8 chromosomes of sorghum were used in double probe hybridization. We found that the two signals are located on different arm of the same chromosome, indicating that there is a inter-chromosomal rearrangement event between S.spontaneum and sorghum.(5)The hybridization signals of number 19 probe and number 66 probe are strong in S.spontaneum, while, the signals scattered on every chromosome and occurred close to the centromere heterochromatin region in sorghum, indicating that the genome of sorghum and S.spontaneum were undergone a significant genome arrangement since their divergence. |
