Mechanism For Disease Resistance Identified In Plants

December 20, 1996

A molecular mechanism for plant disease resistance has been identified for the first time by researchers funded by the National Science Foundation (NSF).

Studying "bacterial speck disease" in tomatoes as a model, the researchers confirmed a decades-old notion that disease resistance in plants is triggered by the interaction of proteins produced by both a resistance gene in the plant and an "avirulence" gene in the disease-causing microorganism. The avirulence protein acts much like an antigen in animals, eliciting an immune response from the plant. Researchers suspect that the resistance mechanism observed in tomatoes also occurs in many other plants. Their results appear in the December 20 issue of the journal Science.

Having identified this basic gene-for-gene resistance mechanism, researchers plan to further explore the phenomenon. Biologist Greg Martin of Purdue University in Indiana says the findings will have wide application.

"It turns out that plants resist diverse pathogens -- including bacteria, fungi and viruses -- by using very similar defense mechanisms. By understanding how a plant recognizes one pathogen, we should begin to understand how plants identify many different pathogens," Martin said.

"This is the first demonstration that there is a lock-and-key mechanism at the molecular level involved with the plant's ability to recognize and mount a resistance response to a pathogen," adds Steven Scofield, a research geneticist at the University of California at Davis Center for Engineering Plants for Resistance Against Pathogens, an NSF Science and Technology Center.

For some 40 years, researchers have known that a plant's ability to fend off an attacking bacterial or viral disease is somehow linked to the complementary activity of genes in both the plant and the pathogen - the disease-causing agent. Previous genetic research has suggested that an avirulence gene in the pathogen triggers a resistance response in the infected plant.

The researchers tested this conjecture using bacterial speck disease, caused by a bacterium known as Pseudomonas syringae pv. tomato (Pst). It is well known that resistance to Pst is contained in the tomato's Pto resistance gene, which has been bred into most commercial tomato varieties. The researchers speculated that the bacterial avirulence gene (AvrPto) enters the plant cell by moving across the plant cell wall and its inner lining, the plasma membrane. Once inside the plant cell, it directly interacts with the tomato plant's Pto resistance gene.

To test this, the researchers first inserted the avirulence gene into a variety of tobacco plant that had been genetically engineered to carry the tomato resistance gene. The tobacco plant was used in this experiment because it was easier to genetically manipulate than a tomato plant. The result was a pattern of cell death or necrosis known to result from the resistance gene, suggesting that the products of the resistance and the avirulence genes were interacting directly.

"These findings set the stage to allow us to genetically engineer disease-resistant crops," Brian Staskawicz, a biologist at UC-Berkeley concludes.

University of California - Davis

Related Pathogens Articles from Brightsurf:

Pathogens in the mouth induce oral cancer
Pathogens found in tissues that surround the teeth contribute to a highly aggressive type of oral cancer, according to a study published 1st October in the open-access journal PLOS Pathogens by Yvonne Kapila of the University of California, San Francisco, and colleagues.

A titanate nanowire mask that can eliminate pathogens
Researchers in Lásló Forró's lab at EPFL, Switzerland, are working on a membrane made of titanium oxide nanowires, similar in appearance to filter paper but with antibacterial and antiviral properties.

Plastics, pathogens and baby formula: What's in your shellfish?
The first landmark study using next-generation technology to comprehensively examine contaminants in oysters in Myanmar reveals alarming findings: the widespread presence of human bacterial pathogens and human-derived microdebris materials, including plastics, kerosene, paint, talc and milk supplement powders.

The Parkinson's disease gut has an overabundance of opportunistic pathogens
In 2003, Heiko Braak proposed that Parkinson's disease is caused by a pathogen in the gut that could pass through the intestinal mucosal barrier and spread to the brain through the nervous system.

Crop pathogens 'remarkably adaptable'
Pathogens that attack agricultural crops show remarkable adaptability to new climates and new plant hosts, new research shows.

Inexpensive, portable detector identifies pathogens in minutes
Most viral test kits rely on labor- and time-intensive laboratory preparation and analysis techniques; for example, tests for the novel coronavirus can take days to detect the virus from nasal swabs.

Outsmarting pathogens
A new influenza strain appears each flu season, rendering past vaccines ineffective.

Autonomous microtrap for pathogens
Antibiotics are more efficient when they can act on their target directly at the site of infestation, without dilution.

Acidic environment could boost power of harmful pathogens
New findings published in PLOS Pathogens suggest lower pH in the digestive tract may make some bacterial pathogens even more dangerous.

Protozoans and pathogens make for an infectious mix
The new observation that strains of V. cholerae can be expelled into the environment after being ingested by protozoa, and that these bacteria are then primed for colonisation and infection in humans, could help explain why cholera is so persistent in aquatic environments.

Read More: Pathogens News and Pathogens Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to