The best attack is a good defense for some carnivorous plants
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Insectivorous plants have fascinated biologists for more than a century, but how plants developed the ability to capture and consume live prey remains largely a mystery. Now, Salk scientists, along with collaborators from the University of Washington at St. Louis, has investigated the molecular basis of plant carnivores and found evidence that it evolved from mechanisms that plants use to defend themselves.
Research published on July 11, 2022, in Proceedings of the National Academy of Sciences (PNAS), detailing how calcium molecules move dynamically within cells in the leaves of carnivorous plants in response to touch from live prey. Fluctuations in calcium cause leaf movement to capture prey, possibly through increased production of defense hormones. The findings broaden scientists’ understanding of how plants interact with their environment.
“If we can learn more about how plants such as these and others have adapted to respond to their unique environments, then perhaps we can alter these molecular pathways in the future to develop plants that can withstand harsher conditions,” said one of the authors. senior. Professor Joanne Chory, director of the Salk Plant Molecular and Cellular Biology Laboratory and investigator of the Howard Hughes Medical Institute.
Biologists have understood that plants such as the spoon-leaved sundew (Drosera spatulata) may have adapted carnivores to survive in nutrient-poor conditions. However, sundews are challenging to grow and their DNA was not sequenced until recently, so scientists are having a hard time examining how carnivores work on a cellular level. They’re also unsure how carnivorous plants develop behaviors related to prey capture, such as leaf movement and secretion of digestive enzymes.
“The carnivorous sundew plant is not a model organism,” said Carl Procko, co-author of the paper and staff scientist at the Salk Plant Molecular and Cellular Biology Laboratory. “Less than a handful of laboratories in the world were previously able to genetically modify it, so we had to learn new techniques to examine it closely.”
For this study, the scientists applied genetic tools to describe the dynamic changes in calcium molecules in leaves as insect prey lands on the leaves and is captured there by a sticky secretion. In non-carnivorous plants, calcium signaling plays many vital life support roles, such as triggering the jasmonic acid defense pathway to repel unwanted insect pests. Jasmonic acid also responds to electrical activity, which is an important element of prey capture in some carnivorous plants, including sundews. The scientists wanted to know whether these same defense pathways from non-carnivorous plants might also be required for the sundew’s carnivorous behavior.
The team found that changes in calcium in plant cells are required for the activation of genes normally targeted by jasmonic acid when leaves are bent inward, trapping insects in digestive juices. The researchers further observed that sundew leaves bent less when they were fed non-living prey and when their calcium channels were blocked. These findings suggest that calcium aids in the capture response of insect prey and, along with the work of others, support the idea that jasmonic acid is involved in insect digestion.
“It’s interesting to see how these plants respond to prey-related mechanical stimuli, such as touch,” said Ivan Radin, co-author and research scientist at the University of Washington at St. Louis. “The ability to sense and respond to mechanical forces is something most people don’t associate with plants, especially at this fast time scale. Our work provides a beautiful visual of this fact.”
“The findings suggest that calcium is also involved and likely enhances the jasmonic acid response, similar to how non-carnivorous plants respond defensively to mechanical stimulation from pests,” said Chory, holder of the Howard H. and Maryam R. Newman Chair at Plant. Biology. “This lends further credence to the idea that carnivores in sundews may have been an evolving line of defense.”
Next, the researchers will apply similar genetic techniques to study other carnivorous plants that were previously too difficult to study. They hope to further investigate the molecular basis of prey capture mechanisms to better understand how carnivores evolved in distantly related species and to see if plants could benefit from adapting existing insect and environmental response pathways to survive in challenging environments.
Other writers include Charlotte Hou of Salk; and Ryan Richardson and Elizabeth Haswell of the University of Washington at St. Louis.
New protein helps carnivorous plants sense and trap prey
Dynamic calcium signaling mediates the feeding response of carnivorous sundew plants, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas
Provided by Salk Institute
Quote: Best offense is a great defense for some carnivorous plants (2022, 11 July) retrieved 11 July 2022 from https://phys.org/news/2022-07-offense-great-defense-carnivorous.html
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