Click image for caption and other photo information.

ARS Has Key Role in Sequence Project Aimed at Tomato Menace

The Agricultural Research Service was among several institutions taking part in a recent project that sequenced the genome of a microbe that infects tomato plants and whose close relatives infect many other crops.

The sequencing of the strain of Pseudomonas syringae that causes bacterial speck disease in tomato plants was led by scientists at Cornell University in Ithaca, N.Y., and The Institute for Genomic Research in Rockville, Md. Funded by the National Science Foundation in Arlington, Va., the project is featured online today in the journal Proceedings of the National Academy of Sciences.

Molecular biologist Samuel W. Cartinhour and computational biologist David J. Schneider, both with ARS' U.S. Plant, Soil and Nutrition Research Laboratory in Ithaca, contributed to the joint effort. Their computational analyses of sequence data helped the research team make preliminary findings about the roles of the more than 5,500 genes in P. syringae, including clues as to how it infects plants.

The ARS scientists scanned the sequence to identify a set of short DNA motifs, known as "hrp boxes," that have an important role in activating genes involved in plant disease. They also identified a group of proteins, known as "effectors," that are transported from P. syringae into plant cells during infection.

While the sequenced strain of P. syringae primarily affects tomatoes, it also infects Arabidopsis thaliana. That small, flowering member of the mustard (Brassicaceae) family is widely used as a model organism in plant biology. The strain thus creates a model pair for plant pathogen studies.

In addition, P. syringae is closely related to P. aeruginosa, which can infect humans and animals, and to P. putida, a bacterium with uses in environmental cleanup. It also shares a key infection mechanism with other plant-infecting bacteria.

The Boyce Thompson Institute for Plant Research in Ithaca, the University of Nebraska, the University of Missouri and Kansas State University also took part in the project.

ARS is the U.S. Department of Agriculture's principal scientific research agency.