Researchers explore the secret life of plants

Debby Greenblatt's home - a former school in Avoca, Neb. - is filled with plants. (Photo by Hilary Stohs-Krause, NET News)
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March 26, 2013 - 6:30am

Spring is here, and Nebraska gardeners will soon be digging in the mud with trowels, packets of seeds at their sides – if they aren’t already. Some will try to encourage struggling seedlings with conversation, perhaps to the chagrin of their neighbors. But as research shows, plants are much more complex than we might think.

It’s a brisk spring day in Avoca, Nebraska, a tiny dot on the map about 45 minutes west of Lincoln. If you look carefully, you can see bits of green pushing through the brown winter refuse, reaching for the elusive sunlight.

Even the most novice gardener knows plants have four basic needs: water, carbon dioxide, soil, sunlight.

"What Plants Talk About"


For more on how plants communicate, check out the new Nature documentary, “What Plants Talk About,” airing on NET Television’s NET-1/NET-HD on Wednesday, April 3rd at 7 p.m. CT.

(Watch the trailer at the end of this story.)

The plant orphanage

Debby Greenblatt and her husband live in a former school in Avoca, Neb. and care for literally hundreds of plants. Greenblatt said they're constantly being given new ones, whether it's from students, neighbors or fellow garden club members. After all, they have plenty of space - and Greenblatt said she finds it hard to say "no" to a plant in need of a home. The music school they run provides a steady soundtrack for the leafy tenants, and Greenblatt said she often gives seedlings away to students.

Photos by Hilary Stohs-Krause,
NET News

From L to R: Adelay Idler, Sharon Roberts-Yuen and Debby Greenblatt

Debby Greenblatt and Adelay Idler are not novice gardeners. They’re member and president, respectively, of the Goldenrod Garden Club, which is celebrating its 75th anniversary next week in Avoca. The duo has more than 80 years of gardening experience between the two of them.

 “I try not to swear in front of my plants,” Greenblatt said. “Just in case.”

“They listen though!” Idler said. “I talk to mine.”

After all, they say, there’s more to raising happy plants than just watering them.

“They like Mozart,” Idler confided. “They do well when I play Mozart. They kind of all perk-up … “

Rock music, on the other hand?

“When I’ve played rock and roll, or even Elvis," she said, "they kind of lean away.”

From apocryphal to academic

“Personally, I believe that whatever humans continue to do, repeatedly, over a long time – and we have been talking to plants for a very long time – is always worth checking out scientifically,” said Dr. Monica Gagliano. “Because often what we do so consistently and repeatedly, (we do) because it works.”

Gagliano is a research fellow at the Center for Evolutionary Biology at the University of Western Australia. Her research has found that plants aren’t only listening, they’re also talking … so to speak.

“What we have found is scientific evidence to demonstrate that plants emit their own sound,” she said. “But beside that, they also respond to the same frequency they emit themselves. Those particular frequencies are telling something. What they’re telling is the real question, and we haven’t got an answer for that yet.”

When confronted with their own frequency, plants lean their roots toward the source of the sound, Gagliano said, adding that such action requires a lot of energy and effort. Especially since they only do it for a targeted frequency, she added, it’s clear it’s not a random reaction.

To some, this probably sounds a bit dodgy - plants talking to each other? The idea of plant communication has been hypothesized for decades, but often was met with skepticism or outright hostility by the scientific community. It’s the kind of reaction Gagliano said she’s experienced time and again.

And fair enough, she added: earlier research didn’t exactly have the most rigorous methodology. However, she said she and her collaborators use the same high-tech equipment used to study animals’ aural communication.

“We’re just adapting something that we know works really well in a different system and putting it onto plants,” she said. “I think the evidence that is there is already so compelling that it would be absolute madness to be so narrow-minded (as) to discount it.”

She pointed to the thousands of plant species that have co-evolved with animal species, like blueberries or tomatoes.

“They’re known for their ability to release pollen only and exclusively when they’re buzzed at the right frequency by a specific bee,” she explained. “In fact, this is called ‘buzz pollination,’ and a lot of growers have learned that and are mimicking what the animals are doing to release the pollen from these species.”

The hidden intricacies of plants

“I think it’s fair to say we constantly have been surprised at how complex plants are,” said Michael Fromm with the Center for Plant Science Innovation at the University of Nebraska-Lincoln.  Fromm studies plant memory, a subject he said is often connected by academia to research like Gagliano’s.

But he started researching plants in relation to something seemingly disconnected: drought tolerance. Through observational research, he and UNL collaborators Yong Ding and Zoya Avramova noticed some plants’ drought-responsive genes looked different than others’ in a greenhouse. They theorized it was from previous stress those particular plants experienced.

Turns out, they were right: the plants were holding onto a memory of drought from a few days prior, as they discovered after further study.

“The difference is, after two hours, plants being stressed the first time are quite wilted, and plants that are being stressed the second time wilt very little,” Fromm said.

The plants with memory of drought knew to conserve what water they had, while the plants new to drought weren’t prepared. Fromm compared it to other research that shows when plants are wounded, they release a volatile chemical compound, one you can smell.

“Plants exposed to those volatile chemicals … if you then expose them a second time, they’ll induce a defense response quicker than plants not previously exposed,” he continued. “So that’s a form of communication and memory.”

So what does all this mean? Fromm says research into how plants form drought memory could help scientists create more water-efficient plants and crops.

Gagliano’s talk of frequencies beyond human hearing made me think of dog whistles; might we someday have plant whistles, I ask her?

“I like the idea. I don’t know!” she said with a laugh. “It’s possible.”

For now, the focus is on learning which plants use which frequencies and what those frequencies are saying … are they anti-predatory? Are they warning signals to other plants? Gagliano hopes to build the knowledge base of plant frequencies to the point where we could use sound to keep plants healthy instead of insecticide or pesticide.  

More research is needed, she said, adding that she thinks the science community is turning over a new leaf, so to speak, when it comes to plant study. She called it a “green revolution.”

When I explained Gagliano’s research to the long-time gardeners I spoke with, they joked that you didn’t need expensive research to know that plants were aware of their surroundings.

“I could have saved them a lot of time if they’d just asked me,” said Sharon Roberts-Yuen of Lincoln with a chuckle. After all, Roberts-Yuen has her own solution for faltering plants – in this case, her “needy” African violets.

“The ones that need the most care, I put on the window ledge by my kitchen sink,” she said. “And I talk to them all the time.” 

For more on how plants communicate, check out the new Nature documentary, “What Plants Talk About,” airing on NET Television’s NET-1/NET-HD on Wednesday, April 3rd at 7 p.m. CT.

Watch What Plants Talk About on PBS. See more from Nature.



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