Detection of alien Oryza punctata Kotschy chromosomes in rice, Oryza sativa L., by genomic in situ hybridization

Genomic in situ hybridization (GISH) using total Oryza punctata Kotschy genomic DNA as a probe was applied to detect alien chromosomes transferred from O. punctata (W1514: 2n=2x=24: BE) to O. saliva Japonica cultivar, Nipponbare (2n=2x=24: AA). Only 12 chromosomes in the interspecific hybrids (2n=3x=36: AAB) between autotetraploid of O. saliva cultivar Nipponbare and a diploid strain of O. punctata (W1514) showed intense staining by FITC in mitotic metaphase spreads. Only one homologous pair of chromosomes out of the 12 pairs of O. saliva chromosomes, which is probably chromosome 8, contained similar repetitive sequences as present in O. punctata and were frequently slightly stained by GISH. Monosomic alien addition line(MAAL)s 7 (2n=2x+1=25: AA+7B: Type II) and 10 (2n=2x+1=25: AA+10B) were characterized by an additional single chromosome which had been intensely stained by GISH. Thus, GISH using O. punctata total genomic DNA allowed the detection of a specific chromosome transferred into cultivated rice. This method can be useful to search introgressed chromosomal segments or translocated chromosomes in the progenies of the MAALs each carrying an alien chromosome of O. punctata in rice.