Plant, Animal & Microbe Genomes X Conference Plant, Animal & Microbe Genomes X ConferenceJanuary 12-16, 2002
Town & Country Convention Center
San Diego, CA
Poster: Microbial Sequencing and Genome Programs
Bacterial ring rot of potato is caused by the gram-positive bacterium, Clavibacter michiganensis subsp. sepedonicus (Cms). Analysis of high-molecular weight DNA has revealed basic information about genome size, organization and heterogeneity in this economically important yet largely uncharacterized pathogen. The minimal genome size of Cms was estimated by CHEF gel analysis to be 2.5 to 2.6 Mb. Genomic fingerprints generated with different restriction enzymes revealed a high degree of genetic similarity within the subspecies. Differences between genomic fingerprints of virulent and avirulent stains were nonetheless detected. Here, we report that the undigested genomes of 11 strains of Cms contain a previously unreported band of either 90 or 140 kb. The intensity and reproducibility of the bands under different CHEF gel conditions indicated that these were linear plasmids. The bands were not be attributed to the circular plasmid, pCS1, common in Cms, because strains lacking pCS1 contained the band and digestion with various restriction enzymes did not produce patterns predicted for pCS1. The linear plasmid is designated pCSL to distinguish it from the circular plasmid, pCS1. We propose the term pCSL1 and pCSL2 for the 90 kb and 140 kb plasmids, respectively. These are the first linear plasmids to be described for the genus Clavibacter . The complete genome sequencing project of Cms is underway.