by Plants can do amazing things. As if the wonders of photosynthesis—the production of oxygen from the sun to power almost all life on Earth—were not enough—humans have collaborated with plants on some mind-blowing projects.
Scientists taught spinach send emails; generated electricity from bushes; and found out how they teach theirs extract to adapt to climate change.
But some of the things people are doing with plants are also limiting their powers, a new study on tomatoes shows.
Researchers at the University of Illinois Urbana-Champaign investigated what happens when tomatoes are visited by ‘friends’ and ‘enemies’ – beneficial soil microbes and caterpillars. Their findings take us deeper into the communication style of one of the world’s most delicious species.
Esther Ngumbi, assistant professor of integrative biology at the university and recent co-author studyevangelical about “the gospel of plant chemistry.”
“People tend to think that plants are not intelligent, but our studies have shown that they are actively responding to the environment around them using chemistry,” she says.
How do plants communicate?
Plant chemistry, according to Ngumbi, is the language that plants use to communicate. It is in the form of volatile organic compounds (VOCs) that they produce to affect the outside world.
VOCs can be sent out with plants for various reasons – as a sign of injury; prepare their defenses, or warn each other about threats to the environment. Sometimes people can pick up on these signals too – catching the smell of cut grass, for example.
These chemical messages can also be used to recruit beneficial soil microbes that help plants grow, such as enteric mycorrhizal fungi (AMF). Or tell insect predators that a pest is chewing on its leaves while trying to disappear.
“When a caterpillar chews on a leaf, the plant sends out a signal that calls out to the caterpillar’s predators. It’s like a billboard that tells them where lunch is,” explained Erinn Dady, another co-author of the study to the team at Carl R. Woese Institute for Genomic Biology (IGB).
Since they cannot run away from danger, this type of chemical fight gives plants the best chance of survival. And it helps us help them by understanding the factors that influence VOC emissions.
Heirlooms vs. hybrids: What do tomatoes tell us?
Building on research that looks at how soil microbes or caterpillars influence VOCs, the researchers wanted to examine the mutual influence of both friends and enemies.
To expand the field of study, they looked beyond where they grew industrially tomatoes to test four different varieties grown by Illinois farmers on a smaller scale. Two hybrids were selected on that basis – Mountain Fresh and Valley Girl – and two organic heirlooms, Amish Paste and Cherokee Purple.
For these four types, the researchers compared the responses of plants left alone, those exposed to AMF, caterpillars or both. The eight-week-old plants were covered in an odor-blocking oven bag for an hour to trap the VOCs they released. This air was then analyzed for its various chemical components.
The results were… a bit confusing. In addition, the AMF and the caterpillars reduced the volatile emissions from the four types of plants. And the emissions didn’t change much when both were present. It is not entirely clear why the beneficial fungi reduced the VOCs, and why the plants were not more responsive to the crawling caterpillars.
But one key finding is that the hybrid tomatoes emit lower amounts of VOCs compared to their heirloom neighbors.
“Heirloom tomatoes – the big, juicy tomatoes we all love – are bred for flavor. Meanwhile, hybrids are grown for traditional large-scale production, which comes at a cost to the plant,” says Ngumbi.
“Our work shows that we are interfering with plant defenses through our breeding processes.”
Why did caterpillar chewing plants grow bigger?
The tomato tests yielded one more baffling result that left the researchers down a new line of inquiry.
They also measured the growth of plants above ground and in the soil. Not surprisingly, the plants with fungal associations developed more leaves and more complex root structures. Further proof of how incredible cooperative fungi can be.
“AMF partners in more than 80 percent of land plants, setting up a trade in which the fungi extract nutrients from the soil in exchange for carbon from plants,” Dady explains.
But the plants treated with caterpillars also had greater growth.
“These plants had more biomass in their roots and above ground, which seems counterintuitive to them because they are actively being eaten. I assume they would have less biomass,” Dadi told the site. of the university.
“The caterpillars may have triggered a growth response, similar to how you cut a tree to produce new growth.” Ngumbi also speculated that the plants the number of caterpillars could be unhindered, and so they grew. Or the caterpillars weren’t hungry enough to do real damage.
“There’s a lot going on behind the scenes that we don’t understand yet,” Dady said, adding that researchers have many other clues to the conversation.
