Abstract:

A fluorescence in situ hybridization (FISH) procedure was adopted to physical mapping two BAC clones 20M14 (27 kb) and 64O9 (36 kb) which linked to the brown planthopper resistance gene Bph15, in O. glaberrima Steud., O. officinalis Wall, and O. latifolia Desv. The results showed that 20M14 and 64O9 were both located on the short arm of chromosome 4 in O. officinalis and O. glaberrima. The percentage distances from the centromere to hybridization sites were 37.03±4.11 and 81.22±3.62, the detection rates were 41.18% and 38.22% in O. officinalis and O. glaberrima, respectively. But in O. latifolia, signals were detected on the short arm and centromere area, with the percentage distances of 87.78±5.23 and 0, and the detection rate of 52.58%, respectively. The two BAC clones were syntenic and distributed in the same area of 4S chromosome of O. officinalis and O. glaberrima, and the homologous sequences of Bph15 were detected in DD genome of O. latifolia. Many signals on different chromosomes of O. glaberrima were observed without C_0t-1 DNA blocking, showing that repetitive sequences were also homologous in three species. The comparative physical mapping analysis showed the location of Bph15 in these three species. The relationships among three species in term of the results of location of Bph15 were discussed, and the knowledge of the genetic relationship among different species in genus Oryza is helpful to conservation and utilization of Bph15. The evolutive mechanism of gene function in different genomes, diploid, and tetraploid species is also discussed.

Key words: O. officinalis, O. latifolia, BAC-FISH, Comparative physical mapping, Bph15