Abstract:Microdissected iR chromosomes of rye ( Secale cereale L. ) were amplified by Sau3A linker adaptor mediated PCR (LA-PCR) for two rounds. After demonstration by Southem hybridization, that their PCR products were originated from the genome of rye, the second round PCR products of the chromosome IR, rye genomic DNA and rDNA were used as probes to hybridize in situ with metaphase chromosomes of mot-tip cells. It was found that the PCR products from microdissected 1R chromosomes included a large amount of IR chromosome-nonspecific repetitive sequences. However, its information capacity was fewer than the total rye genome. While blocking with proper amount of genomic DNA, the second round PCR products from the microdissected iR chromosomes were successfully relocated to the pair of 1R chromosomes in mitotic metaphase, indicating that the PCR products certainly contained iR chromosome specific fragments. In addition, a highly repetitive sequence and a low/single copy sequence selected from the microclone library of chromosome 1R were used as probes. Chromosome in situ hybridization inspected that the repetitive sequence probably was a telomeric relative sequence. But no signal was detected with the low/single copy probe. These data suggest that chromosome painting is a useful way to confirm the origination of microdissected chromosomes and to screen chromosome-specific probes. This research has established a consulted experimental system for plant chromosome painting, which could provide convenience for further apphcations of chromosome microcloning techniques in plants.