Abstract

Genomic in situ hybridization was used to detect introgressed segment from Oryza australinesis onto the chromosomes of introgression line derived from the hybrid O. sativa x O. australinesis. Genomic DNA from Oryza australinesis was labeled with biotin and hybridized to the homologous sequences on the O. sativachromosomes. The probe hybridization fluoresced green and non labeled O. sativachro-mosomes appeared red or blue due to counterstaining with propidium iodide (PI) or 4,6-diamidino-2-phenylindole (DAPI). This differential painting of chromosomes unequivocally detected the introgressed segment. Among the 200 cells analyzed, 6.5% of the cells showed hybridization signal. Signal appeared on one chromosome in 5%, on two homologous chromosomes in 1% and on sister chromatids in 0.5% of the cells. Hybridization was seen on the short arm of the chromosome 12 of the introgression line.

Key words: Genomic in situ hybridization, wide hybrid, localizing introgression.