Do Plants Have Surprising Intelligence? Cornell Discovers in Goldenrod

Recent research reveals that goldenrod plants exhibit a form of intelligence by adjusting their responses to herbivores based on neighboring plants and environmental cues, challenging conventional notions of intelligence.

Goldenrod can sense the presence of nearby plants without physical contact, using cues like far-red light ratios reflected from leaves. When grazed upon by herbivores, it modifies its response depending on the proximity of other plants. Does this dynamic, adaptive behavior signify intelligence in plants?

Addressing this complex question, Andre Kessler, a chemical ecologist, argues for plant intelligence in a recent paper published in Plant Signaling and Behavior.

Defining Intelligence in Plants

“There are over 70 published definitions of intelligence, and even within a single field, consensus is lacking,” notes Kessler, a professor in the Department of Ecology and Evolutionary Biology at the College of Agriculture and Life Sciences.

While some argue that intelligence necessitates a central nervous system, where electrical signals facilitate information processing, some plant biologists liken plant vascular systems to central nervous systems, suggesting a centralized mechanism enables information processing and response. However, Kessler opposes this notion outright.

“There isn’t compelling evidence supporting any similarities with the nervous system, despite the presence of electrical signaling in plants. The key question is how significant this signaling is for a plant’s ability to interpret environmental cues,” he explained.

To argue for plant intelligence, Kessler and his doctoral student Michael Mueller simplified their definition to its core components: “The capability to solve problems using information gathered from the environment to achieve specific objectives,” Kessler stated.

Goldenrod’s Response to Herbivory

As an example, Kessler cited his previous research on goldenrod, focusing on how the plant reacts when attacked by herbivores. When leaf beetle larvae feed on goldenrod leaves, the plant releases a chemical signal indicating damage and discouraging further feeding.

These airborne chemicals, known as volatile organic compounds (VOCs), are also detected by nearby goldenrod plants, prompting them to enhance their defenses against the beetles. This mechanism allows goldenrods to redirect herbivores to neighboring plants and distribute the damage effectively.

In their 2022 study in Plants, Kessler and co-author Alexander Chautá, Ph.D. ’21, demonstrated that goldenrod can detect higher far-red light ratios reflected from neighboring plants’ leaves.

When neighboring plants are around and goldenrods are attacked by beetles, they invest more in tolerating herbivory by growing faster and producing defensive compounds. In the absence of neighbors, goldenrods do not accelerate growth when attacked, and their responses to herbivores differ significantly, although they still tolerate substantial herbivory.

“This aligns with our definition of intelligence,” Kessler noted. “The plant adjusts its behavior based on environmental cues.”

Detecting VOCs to Predict Future Herbivory

Neighboring goldenrods also demonstrate intelligence by detecting volatile organic compounds (VOCs) that indicate pest presence. “The emissions from a neighboring plant predict future herbivory,” Kessler explained. “They use this cue to anticipate and prepare for future challenges.”

According to Kessler, applying the concept of intelligence to plants can lead to new hypotheses about how plant chemical communication mechanisms function, and it can also challenge conventional views on intelligence itself.

This notion is particularly relevant today amidst discussions about artificial intelligence. Kessler pointed out that artificial intelligence, as currently defined, doesn’t solve problems with a specific goal in mind—at least not yet. “By our definition of intelligence, artificial intelligence isn’t truly intelligent,” he remarked. Instead, it relies on identifying patterns within accessible information.

Kessler finds inspiration in an idea proposed by mathematicians in the 1920s, suggesting that plants may operate akin to beehives, where each cell functions like an individual bee and the entire plant resembles a hive. “In this model, the plant’s ‘brain’ is the entire organism, functioning without central coordination,” he explained.

Unlike animals with nervous systems, plants predominantly use chemical signaling rather than electrical signaling throughout their ‘superorganism.’ Research by other scientists indicates that every plant cell possesses a broad spectrum of light perception and specific sensory molecules to detect volatile compounds emitted by neighboring plants.

“As far as we know, each cell can precisely detect its environment through smell,” Kessler added. While cells may have specialized functions, they collectively perceive and communicate using chemical signals to coordinate growth or metabolism. “This concept resonates strongly with me,” he concluded.

Read the original article on: ScietechDaily

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