Traditional
thought holds that a disease-causing organism has to penetrate a plant to
initiate resistance. Now, two Washington
State University
scientists have established that a barley plant recognizes an invader and
begins to marshal its defenses within five minutes of an attack.
The discovery, along with the scientists’ successful cloning of barley’s disease-fighting gene and the pathogen’s signaling gene, could help to revolutionize the battle against cereal crop enemies such as stem rust.
The discovery, along with the scientists’ successful cloning of barley’s disease-fighting gene and the pathogen’s signaling gene, could help to revolutionize the battle against cereal crop enemies such as stem rust.
Unless
carefully controlled, stem rust has the potential to destroy a grower’s entire
crop. It has caused the loss of millions of dollars of grain. Meanwhile, new
threats are on the horizon. For example, Ug99 is becoming a threat to wheat,
posing a new threat to global food security.
Andy
Kleinhofs, professor of molecular genetics in WSU’s Department of Crop and Soil
Sciences, has been working with assistant research professor Jayaveeramuthu
Nirmala to understand the mode of action of Rpg1, a gene that provides barley
with resistance to the pathogen that causes stem rust. The scientists’ latest work involves a deeper
understanding of how Rpg1 and the genes that activate it work to trigger
resistance to stem rust.
In the
course of their investigations, Kleinhofs and Nirmala found that that the plant
recognizes the pathogen within five minutes of the spore touching the leaf,
before penetration of the leaf takes place.
The
plant’s initial reaction to attack is invisible to the human eye, Nirmala said,
but she succeeded in monitoring subtle changes in plant chemistry that
demonstrated the plant not only recognized it was under attack but was starting
to muster its resistance.
Visible
signs of the stem rust spore’s impact come within an hour, when pad-like
lesions connecting the spore to the leaf cell begin to appear.
Camille
Steber, a research geneticist for the U.S. Department of Agriculture’s
Agricultural Research Service at WSU, said Steber said the discovery is a
game-changer for plant scientists.
"This
is the first example where the lock-and-key of cereal-pathogen response is
clearly understood,” she said.
Kleinhofs
said, "There is still a lot to be learned,” he added. "As with any
new discovery, more questions arise than have actually been answered, but it’s
a good start.”
Contacts:
Andy
Kleinhofs, professor, Department of Crop and Soil Sciences and School
of Molecular Biosciences,
509-335-4389, andyk@wsu.edu
Jayaveeramuthu
Nirmala, assistant research professor, Department of Crop and Soil
Sciences,509-335-5272, nirmala@wsu.edu
Kathy
Barnard, Marketing, News, and Educational Communications, 509-335-2806, kbarnard@wsu.edu