Agrobacterium tumefaciens causes crown gall disease in plants. Crown gall is characterized by the growth of tumors, or "galls" in variety of plant species. To better understand how the organism causes disease, Kado and his colleagues investigated the evolutionary origin of genes they believed to be associated with the bacterium's virulence. One of these was a gene called ros.
"Since A. tumefaciens is a plant pathogen, we naturally thought that plants would be the most likely source of the gene," says Kado. "In mining the genomic databases, though, we didn't find it in plants. Instead we found a homolog of the ros gene in the genome of puffer fish."
The discovery of a distantly similar gene in puffer fish suggests that perhaps Agrobacterium, which is found on land, may have originated from a marine organism rather than a terrestrial one, says Kado.
"In support of this hypothesis, we have isolated a number of marine microorganisms from marine sources such as sea squirts, and at least three microbial species contain ros homologs as well," he says.
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Contact: Jim Sliwa
jsliwa@asmusa.org
202-942-9297
American Society for Microbiology
30-Jan-2003