AsianScientist (May. 11, 2023) –Plants have long been known to respond to various stimuli, such as light and touch, but a recent study sheds light on an astonishing fact – plants scream when they are under stress. The study, published in Cell, was conducted by a team of researchers from Tel Aviv University in Israel and recorded the sounds of tomato and tobacco plants when put under stressful conditions including dehydration and after their stems had been cut.
The research team used highly sensitive microphones to detect sounds emitted by the plants placed in a chamber with low water availability. The recordings were then processed to remove background noise and analyze the specific frequency range of the sounds emitted by the plants. Moreover, they also used a machine learning algorithm to differentiate the sounds produced by stressed and unstressed plants. The team found that stressed plants emit ultrasonic sounds (20-100 kilohertz) in the form of popping or clicking noises that can be detected within a radius of over a meter. Other organisms, including insects and animals, may be able to detect these sounds, the researchers noted.
“There are sounds present in quiet places that we don’t hear. However, there are animals hearing these sounds, indicating the possibility of acoustic interactions occurring,” said Lilach Hadany, the corresponding author and biologist from the School of Plant Sciences and Food Security, Tel-Aviv University, in an article published by ScienceAlert.
The team found that stressed plants emit an average of up to 40 clicks per hour, unlike unstressed plants, depending on the species. Plants deprived of water have a distinct sound profile, clicking more before they show visible signs of dehydration. The sounds escalate as the plant dries and then subside as the plant withers away. The sounds emitted by the plants are in the ultrasonic frequency range, which is out of human hearing range.
The team tested various plants, including wheat, corn, grape and cactus and found that sound production appeared to be a common activity among them. However, it is not clear how the sounds are being produced. The sounds observed in dehydrated plants may be attributed to cavitation – a phenomenon in which air bubbles form, expand, and collapse within the stem.
The study’s findings raise questions about the adaptive developments in plants and whether sound production is one of them. It is unknown whether other distress conditions, such as pathogens, attacks, UV exposure, or temperature extremes, can induce sounds in plants. The team is currently working on the responses of other living organisms, both plants & animals, to these sounds.
“We are currently trying to learn about the response of other plants and animals to these sounds as well as identify and interpret the sounds in completely natural environments,” said Hadany.
Source: Tel Aviv University ; Image: Shelly Liew/Asian Scientist Magazine
The article can be found at: Sounds emitted by plants under stress are airborne and informative
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