Now, researchers at the Boyce Thompson Institute for Plant Research (BTI) on the Cornell campus have identified the elusive signal in the process: methyl salicylate, an aspirin-like compound that alerts a plant's immune system to shift into high gear.
This phenomenon is called systemic acquired resistance and is known to require movement of a signal from the site of infection to uninfected parts of the plant.
The findings are published in the Oct. 5 issue of Science.
"By finally identifying a signal that moves from an infection site to activate defenses throughout the plant, as well as the enzymes that regulate the level of this signal, we may be in a position to alter the signal in a way that enhances a plant's ability to defend itself," said BTI senior scientist Daniel F. Klessig, an adjunct professor in plant pathology at Cornell, who conducted the work with Sang-Wook Park and other BTI colleagues.
Their approach, using gene technology to enhance plant immunity, could have wide consequences, boosting crop production and reducing pesticide use.
Methyl salicylate is a modified form of salicylic acid (SA), which has been used for centuries to relieve fever, pain and inflammation, first through the use of willow bark and, since 1889, with aspirin, still the most widely used drug worldwide.
In the 1990s, Klessig's research group reported that SA and nitric oxide are two critical defense-signaling molecules in plants, as well as playing important roles in human health. Then, in 2003 and 2005, the group reported in the Proceedings of the National Academy of Sciences that an enzyme, salicylic acid-binding protein 2 (SABP2), is required for systemic acquired resistance and converts methyl salicylate (which is biologically inactive as it fails to induce immune responses) into SA, which is biologically active.
After plants are attacked by a pathogen, the researchers had previously found, they produce SA at the infection site to activate their defenses. Some of the SA is converted into methyl salicylate, which can be converted back into SA by SABP2.
Using plants in which SABP2 function was either normal, turned off or mutated in the infected leaves or the upper, uninfected leaves, Klessig's group showed that SABP2 must be active in the upper, uninfected leaves for systemic acquired resistance to develop properly. By contrast, SABP2 must be inactivated in the infected leaves by binding to SA.
"This inactivation allows methyl salicylate to build up," explained Klessig. "It then flows through the phloem (or food-conducting "tubes") to the uninfected tissue, where SABP2 converts it back into active SA, which can now turn on the plant's defenses."
Klessig said that it is unclear why plants send this hormone to uninfected tissue in an inactive form, which then must be activated by removal of the methyl group.
"This research also provides insight into how a hormone like SA can actively regulate its own structure -- and thereby determine its own activity -- by controlling the responsible enzyme," noted Park, the lead author of the paper.
Blaine Friedlander | EurekAlert!
Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover
First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences