When disease-resistant rice is invaded by disease-causing bacteria, a small protein produced by the bacteria betrays the invader. Upon recognizing that protein, the rice plants sense that a microbial attack is underway and are able to mount an immune response to fend off bacterial infection, reports a research team led by the University of California, Davis.
Identification of the tiny protein, called RaxX, holds promise for developing more disease-resistant crop varieties and therapeutic treatments for blocking microbial infections in both plants and animals, said the researchers, who found particular satisfaction in this discovery, two years after retracting the announcement of a similar find.
Discovery unlocks clues to disease protection:
In this new study, researchers discovered that the RaxX protein was present in at least eight species of the disease-causing Xanthamonas bacteria that are known to attack rice -- the staple food for half of the world's population -- as well as maize, cassava, sugar cane, tomatoes, peppers, wheat, alfalfa, onions, banana and citrus.
"Our research team is delighted to announce the discovery of the RaxX protein, a new class of microbial signaling molecules ," said Pamela Ronald, a professor in UC Davis' Department of Plant Pathology and Genome Center, who directed the study.
Ronald noted that her laboratory is currently investigating the role of RaxX during bacterial infection of rice in the absence of the immune receptor.
The researchers have noticed that RaxX closely resembles a class of plant signaling factors that promote growth and modulate the immune response. They suspect that the bacteria could be mimicking these natural plant-signaling factors to inhibit the plant immune response and thereby enhance the competitiveness of the bacteria.
In the long term, the researchers hope to use this information to develop new strategies to prevent infection in various crops.
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