Uncovering the mystery of a major threat to wheat

Jun 01, 2010

Agricultural Research Service (ARS) scientists have solved a longstanding mystery as to why a pathogen that threatens the world's wheat supply can be so adaptable, diverse and virulent. It is because the fungus that causes the wheat disease called stripe rust may use sexual recombination to adapt to resistant varieties of wheat.

ARS plant pathologist Yue Jin and his colleagues Les Szabo and Marty Carson at the agency's Cereal Disease Laboratory at St. Paul, Minn., have shown for the first time that stripe rust, caused by Puccinia striiformis, is capable of sexually reproducing on the leaves of an alternate host called barberry, a common ornamental. The fungus also goes through asexual mutation. But sexual recombination offers an advantage because it promotes rapid reshuffling of virulence gene combinations and produces a genetic mix more likely to pass along traits that improve the chances for survival.

Barberry (Berberis spp) is already controlled in areas where is threatened by , caused by another . But the work by the ARS team is expected to lead to better control of barberry in areas like the Pacific Northwest, where cool temperatures during most of the wheat growing season make stripe rust a particular threat.

The researchers suspended wheat straw infected with the stripe rust pathogen over barberry plants and found that from the wheat infected the barberry. They also took infected barberry leaves, treated them to promote the release of spores, and exposed them to wheat. Tests confirmed that the wheat plants were infected within about 10 days.

The researchers began the study last year after finding infected leaves on barberry plants at two sites on the University of Minnesota campus. They initially thought the symptoms were a sign that the stem rust pathogen had overcome the resistance commonly found in U.S. varieties of barberry.

Instead, they found barberry serving as a sexual or "alternate" host for stripe rust. When the overwintering spores of the stripe rust fungus germinate in the spring, they produce spores that reach barberry leaves, forming structures on the top of the leaves that allow mating between races or strains of the fungus. Spores resulting from this mating can, in turn, infect wheat.

Explore further: Mussels on California Coast contaminated with giardia transmitted from land-based sources

More information: The results were recently published in Phytopathology.

Provided by United States Department of Agriculture

4 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Elusive rust resistance genes located

Dec 06, 2006

The discovery of a DNA marker for two key rust resistance genes is enabling plant breeders around the world to breed more effective rust resistant wheat varieties.

Dangerous wheat disease jumps Red Sea

Jan 16, 2007

A new form of stem rust, a virulent wheat disease, has jumped from eastern Africa and is now infecting wheat in Yemen in the Arabian Peninsula.

Gene to reduce wheat yield losses

Feb 19, 2009

A new gene that provides resistance to a fungal disease responsible for millions of hectares of lost wheat yield has been discovered by scientists from the US and Israel.

Scientists fight stem rust UG99 before it becomes a threat

Nov 18, 2008

(PhysOrg.com) -- Wheat breeders and plant pathologists at Montana State University are part of a global effort to develop varieties of wheat resistant to a new fungus. UG99, a stem rust strain that was first discovered in ...

Researchers find rust resistance genes in wild grasses

Oct 21, 2008

(PhysOrg.com) -- University of Adelaide researchers have identified new sources of stem and leaf rust resistance in wild grass relatives of wheat sourced mostly from the 'fertile crescent' of the Middle East.

New wheat disease could spread faster than expected

Mar 25, 2009

Both plant and human diseases that can travel with the wind have the potential to spread far more rapidly than has been understood, according to a new study, in findings that pose serious concerns not only for some human ...

Recommended for you

Is fleet diversity key to sustainable fisheries?

20 hours ago

Concern about fisheries is widespread around the world. Over the past several decades, a robust discussion has taken place concerning how to manage fisheries better to benefit ecosystems and humans. Much of the discussion ...

Strange, fanged deer persists in Afghanistan

21 hours ago

More than 60 years after its last confirmed sighting, a strange deer with vampire-like fangs still persists in the rugged forested slopes of northeast Afghanistan according to a research team led by the Wildlife ...

Captive rhinos exposed to urban rumbles

22 hours ago

The soundtrack to a wild rhinoceros's life is wind passing through the savannah grass, birds chirping, and distant animals moving across the plains. But a rhinoceros in a zoo listens to children screaming, cars passing, and ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.