Development and applications of a set of chromosome-specific cytogenetic DNA markers in potato

Reliable and easy to use techniques for chromosome identification are criti cal for many aspects of cytogenetic research. Unfortunately, such technique s are not available in many plant species, especially those with a large nu mber of small chromosomes. Here we demonstrate that fluorescence in situ hy bridization (FISH) signals derived from bacterial artificial chromosomes (B ACs) can be used as chromosome-specific cytogenetic DNA markers for chromos ome identification in potato. We screened a potato BAC library using geneti cally mapped restriction fragment length polymorphism markers as probes. Th e identified BAC clones were then labeled as probes for FISH analysis. A se t of 12 chromosome-specific BAC clones were isolated and the FISH signals d erived from these BAC clones serve as convenient and reliable cytological m arkers for potato chromosome identification. We mapped the 5S rRNA genes, t he 45S rRNA genes, and a potato late blight resistance gene to three specif ic potato chromosomes using the chromosome-specific BAC clones.