Lexington, Kentucky, USA
May 14, 2014
Nitric oxide production in pathogen-infected leaves - Photo: Pradeep and Aardra Kachroo
University of Kentucky College of Agriculture, Food and Environment scientists have identified more key components to activating disease resistance in plants.
"This work is important because it connects the different puzzle pieces of systemic immunity, so we can begin to see the connections between the pieces and the framework of an overall picture," said Aardra Kachroo.
Aardra Kachroo and her husband Pradeep Kachroo are researchers in the UK Department of Plant Pathology and study the RNA silencing pathway in plants. Through this pathway, a plant can trigger one of two types of resistance to fend off bacterial and viral pathogens. This pathway exists in all sorts of organisms.
Researchers in their labs found that cell-signaling molecules nitric oxide and reactive oxygen species are required to start systemic-acquired resistance. This form of resistance protects plants against infections that may occur as a result of treating another infection. When genetic mutations in plants either prevent the production of these two molecules or only increase the production of nitric oxide, the plant cannot produce this kind of resistance.
"Nitric oxide and reactive oxygen species are already well known to be associated with many human disorders,” said Pradeep Kachroo. “Although they have long been identified as signaling molecules in plants as well, it is exciting to know they are also key regulators of systemic immunity. This is the closest system in plants to the human circulatory immune system."
Medical researchers have linked an imbalance of nitric oxide and reactive oxygen species in the human body to incurable age-related, neurodegenerative diseases like Alzheimer’s and Parkinson’s, as well as many types of cancers.
“Some levels of ROS (reactive oxygen species) are actually needed for human well-being and are in fact beneficial,” said Pradeep Kachroo. “This is the same for plants. Too little or too much of ROS/nitric oxide can impair many processes including plant immunity."
Researchers involved with the finding are Caixia Wang, Mohamed El-Shetehy, M.B. Shine, Keshun Yu, Duroy Navarre and David Wendehenne. All are current or former members of one of the Kachroo labs.
The Kachroos also have discovered other necessary components of plant disease resistance including the metabolite glycerol-3-phosphate and the protein DRB4.
Their most recent findings were published in Cell Reports.
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