FISH on Plant Chromosomes

FISH, which allows the mapping of DNA sequences directly onto chromosomes, has revolutionized plant molecular cytogenetics research since it was first adapted from mammalian research. Repetitive DNA sequences can generate unique FISH patterns on individual chromosomes for karyotyping (chromosome identification) and phylogenetic/evolution analyses. FISH and/or genomic in situ hybridization (GISH) on meiotic metaphase chromosomes provide more information on chromosome pairing than traditional pairing analysis. FISH on meiotic pachytene chromosomes coupled with digital imaging systems has become an efficient method for developing physical maps in plant species, especially those with small genomes. FISH-based physical mapping provides a valuable complementary approach to genome sequencing and map-based cloning research, and it will continue to play an important role in relating DNA sequence information to chromosome biology. In addition, FISH using RNA probes and FISH with immunoassays are becoming increasingly important techniques in studies of chromosome structure and functions that control gene expression and regulation.