Mapping the Phytoplasma Chromosome

Physical and genetic mapping of the phytoplasma chromosome can be a useful tool in a genome sequencing project in order to assemble the in silico-predicted contigs robustly. Mapping consists of four distinct steps: preparation of phytoplasma chromosomes from infected plants, single- and double-digestion of chromosomes with rare-cutting restriction enzymes, separation of large DNA fragments by pulsed-field gel electrophoresis, and hybridization with various genetic markers. Materials and methods needed for each step are described and the technique is illustrated using the flavescence dor�e phytoplasma genome map as an example.