From: LARRY KLAES (ljk4_at_msn.com)
Date: Sat Aug 16 2003 - 09:47:09 PDT
----- Original Message -----
From: cunews_at_cornell.edu
Sent: Friday, August 15, 2003 10:48 PM
To: CUNEWS-AG-L_at_cornell.edu; CUNEWS-LIFE_SCIENCE-L_at_cornell.edu; CUNEWS-SCIENCE-L_at_cornell.edu
Subject: Cornell News: Pseudomonas syringae sequenced
Leading bacterial pathogen is sequenced, providing hope for new
defenses in plant and possibly human disease, says Cornell researcher
(Please note: earlier versions of this release were embargoed until
Monday, Aug. 18, 2003. PNAS has lifted the embargo.)
Contact: Blaine P. Friedlander Jr.
Office: 607-255-3290
E-mail: bpf2_at_cornell.edu
ITHACA, N.Y. -- The complete genome sequence of a leading bacterial
plant pathogen offers new ways to stave off agricultural loss and
perhaps foil animal or human infection, says a Cornell University
researcher.
According to Alan Collmer, Cornell professor of plant pathology, the
sequencing (that is, determining the base sequence of each of the
ordered DNA fragments in the genome) could help farmers repress
tomato speck and other plant diseases. Medical researchers could be
aided in comparing a related bacterium that causes fatal lung
infections in cystic fibrosis patients. And environmentalists could
be provided with a new tool in understanding how another related
bacterium can live in soil and dine on toxic waste.
The sequencing of Pseudomonas syringae (strain DC3000) is reported on
the Web today (Aug. 18) by scientists from Cornell and The Institute
for Genomic Research (TIGR) in the Proceedings of the National
Academy of Science (PNAS Online Early Edition).
The P. syringae genome will be particularly helpful to scientists
studying P. aeruginosa, a bacterial cousin blamed for chronic and
fatal lung infections in cystic fibrosis patients and acute
infections of cancer and burn patients, says Collmer, who is
principal investigator on the project. Comparisons of the genomes, he
says, will help researchers understand how these bacteria have
adapted to their hosts and could reveal weak points to target with
new therapies.
"Understanding this genome connects us to a larger world of bacterial
pathogens," says Collmer. "Pseudomonas syringae (pronounced
soo-dough-MOAN-iss seer-INN-gee) has become a premier model for
studying plant diseases. The genome reveals how complex the jigsaw
puzzle of pathogenesis is. It puts all of the pieces on the table, it
shows us that many parts of the puzzle are the same for plant and
animal pathogens, and it enables scientists to put the pieces
together more efficiently."
The project was funded by the National Science Foundation Plant
Genome Research Program. C. Robin Buell, a biologist with TIGR,
directed the complete sequencing of the genome. Many bacteria that
are animal and plant pathogens -- including the plague bacterium
Yesinia pestis -- inject virulence proteins into healthy host cells
using what is called a "type III secretion system." The researchers
discovered the genes encoding more than 35 injected-virulence
proteins, more than for any other known pathogen, through
collaboration with Cornell Theory Center computational biologists
Samuel Cartinhour and David Schneider of the U.S. Department of
Agriculture's (USDA) Agricultural Research Service.
P. syringae is a major agricultural pathogen, causing bacterial speck
on tomatoes. It produces black lesions, often with a discrete yellow
halo that can appear on the plant leaves and cause them to curl. In
1977-78 the bacteria caused serious losses to the winter tomato crop
in southern Florida. Cool, moist environmental conditions contributed
to the development of the disease, and it had established itself as a
major problem, according to Thomas A. Zitter, Cornell professor of
plant pathology.
In the years before 1977, growers had sprayed a copper-based
pesticide to ward off bacterial speck, but the pathogen became
resistant to the copper, rendering the pesticide virtually useless.
Natural resistance genes have been bred into certain tomato plants to
control the disease. Gregory Martin, Cornell professor of plant
pathology and a scientist at the Boyce Thompson Institute for Plant
Research (an independent research facility on Cornell's campus), and
Steven Tanksley, Cornell professor of plant breeding, cloned the
first such resistance gene in 1993. The gene, Pto, enables tomato
plants to recognize P. syringae and turn on strong defenses.
Over time, however, variants of the pathogen have arisen that can
evade detection. Using information from the sequencing of P.
syringae, Martin, a member of the sequencing team, and other
researchers are now exploring how pathogens adapt to plant defenses.
Other researchers involved in the sequencing research were James R.
Alfano, University of Nebraska-Lincoln; Arun K. Chatterjee,
University of Missouri; Terrence P. Delaney, Cornell assistant
professor of plant pathology; Sondra G. Lazarowitz, Cornell professor
of plant pathology; and Xiaoyan Tang, Kansas State University.
Related World Wide Web sites: The following sites provide
additional information on this news release. They are not part of
the Cornell University and the university has no control over their
content or availability.
o Proceedings of the National Academy of Sciences:
o The Institute for Genomic Research:
o The National Science Foundation:
-30-
The web version of this release may be found at
http://www.news.cornell.edu/releases/Aug03/CollmerBacteria.bpf.html
Cornell University News Service
Surge 3
Cornell University
Ithaca, NY 14853
607-255-4206
cunews_at_cornell.edu
http://www.news.cornell.edu
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