IMAGE: Researchers have found that the caterpillars of tomato fruit worms disturb the appetite of their food plants for help while shedding their leaves. view more
Credit: Nick Sloff, Penn State
UNIVERSITY PARLIAMENT, Pa. – Like a scene from a horror movie, tomato fruit caterpillars hear the cries of their food plants for help while shedding their leaves. That’s the discovery of a multidisciplinary team of researchers, who said the results could shed light on the ability of crop plants – such as tomato and soybean – to withstand additional pressures, such as climate change.
“We have found a new strategy where insects use saliva to prevent the release of airborne plant defenses through direct treatment of plant stomata,” said Gary Felton, professor and the head of the Department of Entomology at Penn State, notes that the stomata of tiny pores on the leaves of plants that regulate gas exchange, including plant protective emissions and carbon dioxide, between the plant and the environment.
In particular, the researchers studied the effects of a specific enzyme – glucose oxidase (GOX) – that occurs in the saliva of tomato fruit caterpillars (Helicoverpa zea) on plant stomata and plant protective releases, called plant is caused by raspberry (HIPV).
“HIPVs are thought to help protect plants from weeds by attracting the natural enemies of these raspberries and by warning nearby plants that weeds are nearby. on hand, “Felton said. “As a result, stomatal closure has the potential to alter interactions throughout the plant community.”
In their experiments, the researchers used CRISPR / Cas9, a method for the preparation of genomes, to remove caterpillars that lack the enzyme GOX. In separate glass chambers with filter traps to collect HIPVs, they allowed the caterpillars with the non-professional enzyme, along with untreated caterpillars, to feed tomato, soybean and cotton plants for three hours. To study stomatal response to GOX, the team examined the leaves of the plant under a microscope and measured the size of stomatal openings. Next, they extracted the volatile fertilizers from the sieve bells and used gas chromatography, along with mass spectrametry, to identify and quantify the HIPVs.
“This study is the first to use CRISPR / Cas9-mediated gene editing to study insect salivary enzyme activity,” said Po-An Lin, a graduate student in entomology at Penn State and lead author of the paper . “Using pharmacological, molecular, and physiological methods, we were able to demonstrate that this salivary enzyme plays a key role in insect-induced stomatal closure and possibly reduces a number of important immune releases.”
In fact, the team – made up of experts in molecular biology, chemical ecology, plant biology and entomology – found that GOX, which is secreted by the caterpillar on leaves, causes stomatal closure. in tomato plants within five minutes, and in tomato and soybean plants for at least 48 hours. They also found that GOX inhibits the release of several HIPVs during feeding, including (Z) -3-hexenol, (Z) -jasmone and (Z) -3-hexenyl acetate, which are important air markers the plant protection. Interestingly, they did not find the effect of GOX on the cotton plants, which, the team said, suggests that the effect of GOX on stomatal behavior is species-dependent.
The team’s results appeared in the journal Jan. 18 de New phytologist.
Lin noted that the fact that tomato fruit caterpillars developed a salivary enzyme that inhibits the release of protective valves in some species shows the importance of plant air defenses in herb evolution. -bests.
“Given the severity of HIPVs in plants, symptoms affecting HIPVs appear to have become widespread among herbivores,” he said.
Not only do these insects harm individual plants, but they may also be less able to withstand climate change.
“Stomata are important organs of plants that not only detect and respond to environmental pressures, but also play a key role in plant growth,” Felton said. “Because stomata play an important role in regulating leaf temperature and leaf water content, our findings suggest that control of insect stomatal opening may affect the plant’s response to elevated temperatures. is reflected in climate change and water response. “
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Other Penn State authors on the paper include Yintong Chen, a graduate student in molecular, cellular and integrated biology; Chan Chin Heu, a former researcher; Nursyafiqi Bin Zainuddin, a graduate student in entomology; Jagdeep Singh Sidhu, a graduate student in gardening; Michelle Peiffer, research support assistant in entomology; Ching-Wen Tan, a graduate scholar in entomology; Jared Ali, former professor of entomology; Jason L. Rasgon, professor of entomology and epidemiology of disease; Jonathan Lynch, Distinguished Professor of Plant Science; and Charles T. Anderson, associate professor of biology. Also on the paper are Duverney Chaverra-Rodriguez, a graduate scholar, University of California, San Diego; Anjel Helms, associate professor of chemical ecology, University of Texas A&M; and Donghun Kim, assistant professor, Kyungpook National University.
This research was supported by the National Science Foundation, the U.S. Department of Agriculture Agricultural and Food Research Initiative Program and the Hatch Project Grant.
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