SEARCHING FOR BAC CLONES CONTAINING PERICENTROMERIC REPEATS OF BUNCHING ONION (ALLIUM FISTULOSUM L.) USING PCR AND FISH ANALYSIS
Bacterial artificial chromosome (BAC) libraries are being used widely in genome researches and developing of markers for identification of individual chromosomes. A combination of BAC clones that possess insertion of large genomic DNA fragments and fluorescence in situ hybridization (FISH) is a powerful tool for genome studies and physical mapping. In this work a PCR analysis of 1016 BAC clones from the A. fistulosum genomic DNA library with primers designed on AfiT32 tandem repeat has been done. The primers were obtained based on bioinformatics analysis of the completely sequenced one selected BAC clone in our previous research. It was revealed three BAC clones containing the AfiT32 repeat. Fluorescence in situ hybridization (FISH) with the clones showed strong signal in pericentromeric regions of chromosomes 5 and 6 of A. fistulosum. These chromosomal markers may be used for integration of genetic and physical maps of A. fistulosum and in onion breeding programs. Future sequencing and analysis of the BAC clones allow us to shed light on genomic structure of pericentromeric and centromeric regions, to elucidate what other repeats, mobile elements and possibly genes are located in these chromosome regions, to answer the question whether the AfiT32 repeat is a part of functional centromere and to establish copy number of the tandem repeat presenting in genome. The data will add to our knowledge about structure of pericentromeric and centromeric regions and, in general, evolution of plant chromosome.