Fungi's genetic sabotage in wheat discovered

July 12, 2010

Using molecular techniques, Agricultural Research Service (ARS) and collaborating scientists have shown how the subversion of a single gene in wheat by two fungal foes triggers a kind of cellular suicide in the grain crop's leaves.

Fortunately, the team has also developed DNA molecular markers that can be used to rapidly screen commercial cultivars for the gene, Tsn1, so it can be eliminated by selective breeding. This, in turn, would deprive the fungi of their primary means of killing off leaf tissue to feed and grow, explains Justin Faris, a plant geneticist with the ARS Cereal Crops Research Unit in Fargo, N.D.

The fungi--Pyrenophora tritici-repentis (also known as tan spot) and Stagonospora nodorum (leaf blotch)--are often partners in crime, occurring in the same crop fields and producing the same toxin, ToxA, to induce a Tsn1-controlled response in wheat called programmed cell death (PCD). Normally, PCD protects plants by confining invading pathogens in dead cells. However, the strategy doesn't work against the ToxA fungi because they're "necrotrophs," pathogens that feed on dead tissue.

To better understand this genetic trickery, Faris led a team of scientists from seven different research organizations in isolating, sequencing and cloning the DNA sequence for Tsn1 from cultivated wheat and its wild relatives. Based on their analysis, the researchers concluded that modern-day wheat inherited Tsn1 from goatgrass. They figure this happened after a goatgrass gene for the enzyme protein kinase fused with another gene, NB-LRR, which probably conferred resistance to biotrophs, pathogens that feed on living tissue.

Interestingly, Tsn1 is controlled by wheat's circadian clock, and only initiates PCD in response to ToxA during daylight hours. At night, Tsn1 shuts down and "ignores" ToxA, suggesting the toxin may indirectly interfere with the plant's photosynthesis.
-end-
The team, which includes researchers from North Dakota State University-Fargo and the Australian Centre for Necrotrophic Fungal Pathogens-Murdoch among others, reported its findings online this week in the Proceedings of the National Academy of Sciences.

ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture (USDA). This research supports the USDA priority of promoting international food security.

USDA is an equal opportunity provider, employer and lender. To file a complaint of discrimination, write: USDA, Director, Office of Civil Rights, 1400 Independence Ave., S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice), or (202) 720-6382 (TDD).

United States Department of Agriculture - Research, Education and Economics

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
Brightsurf.com 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 Amazon.com.