Agrobacterium and Pufferfish May Share Distant Relative

NEW ORLEANS - January 30, 2003 -- What does a bacterium that causes tumors in plants have in common with a puffer fish? They both share a similar gene, suggesting that they may have a common ancestor on the evolutionary tree of life, says Clarence Kado of the University of California, Davis. He presents his findings today at the 3rd ASM/TIGR Conference on Microbial Genomes.

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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The American Society for Microbiology (ASM) is the largest single life science society, composed of over 42,000 scientists, teachers, physicians, and health professionals. Its mission is to promote research and training in the microbiological sciences and to assist communication between scientists, policymakers, and the public to improve health, economic well being, and the environment.

The Institute for Genomic Research (TIGR)is a not-for-profit research institute based in Rockville, Maryland. TIGR, which sequenced the first complete genome of a free-living organism in 1995, has been at the forefront of the genomic revolution since the institute was founded in 1992. TIGR conducts research involving the structural, functional, and comparative analysis of genomes and gene products in viruses, bacteria, archaea, and eukaryotes.