How do plants ‘smell’ danger? That’s the question behind the EU-funded PERVOL project. “When plant leaves come under attack by an insect, they immediately begin releasing a distinct blend of volatile chemicals, which we call volatiles,” explains project coordinator Matthias Erb, who is also a professor at the Institute of Plant Sciences at the University of Bern. These volatiles are perceived by other parts of the plant, causing them to build up a more robust response against the attack. What Erb wanted to know was how plants can sense these volatiles. Do they use receptors similar to animals? How do they translate the perceived cues into defence responses? “Understanding how plants perceive volatiles would push the boundaries of plant signalling research,” he says. “It would also open the door to translating this perception into potential agricultural applications.”
For the PERVOL project, pushing said boundaries began with developing an innovative volatile sampling system. The system combines robotic technology, a customised airflow system, and a proton transfer reaction mass spectrometer. It was developed with the support of TOFWERK, abon LIFE SCIENCES and BIBUS. “Our system is capable of recording the volatile fingerprints of over 100 different sources simultaneously,” notes Erb. “Together with a temporal resolution below 30 minutes, we’ve set a new standard in the field of plant volatile research.” With this system in hand, the researchers next set out to identify the genetic basis and biological consequences of plant volatile perception. “We uncovered that maize plants integrate two volatile cues, indole and hexenyl acetate, into strong and specific defence responses that enhance their resistance against chewing herbivores.” The researchers also studied rice plants, where they found that indole enhances the deployment of the plant’s early defence signalling pathway, including a specific mitogen-activated kinase pathway. Upon indole perception, this kinase increases the production of jasmonate stress hormones, which ultimately leads to a stronger defence.
New insights into plant volatiles
The PERVOL project, which received support from the European Research Council, succeeded at identifying the early signalling components required to perceive herbivore-induced volatiles in plants. “Having the possibility of doing high-resolution volatile screens across many plants has opened our eyes to the rapid and dynamic interplay that occurs between plants that exchange volatile cues,” remarks Erb. “It also advances the field of plant volatile research by providing new insights into the mechanisms of this fascinating phenomenon.” During the project, researchers uncovered a series of novel candidate genes with an unknown function that are likely involved in plant volatile perception and will require further investigation. “We plan to further explore the rapid exchange of volatile information between plants and continue our hunt for volatile perception mechanisms and potential receptors,” concludes Erb.
PERVOL, plants, volatiles, plant signalling, plant sciences, robotic technology, spectrometer