Plants' perception goes DNA-deep
Research suggests plants are highly aware of the world around them.
Scientists have found that when water droplets land on a leaf, it causes an elaborate response inside the plant.
A similar reaction is seen when plants are patted or touched, suggesting that they can sense what is happening to them.
Experts from Australia’s ARC Centre of Excellence in Plant Energy Biology suggest that this touch response may prepare a plant to defend itself from danger, or let it take advantage of changes in the weather.
The findings could change how we interact with plants.
“While nothing visibly happens to plants when they are touched, their ‘touch response’ launches a cascade of signals inside leaves that prepare them for the future” said lead researcher Dr Olivier Van Aken, from the University of Western Australia.
The changes go right down to the genetic level, causing a shift in the expression of thousands of plant genes they are sprayed with water.
The dramatic response occurred within only minutes of spraying and stopped in half an hour.
“We were able to show that this response was not caused by any active compounds in the spray but rather by the physical contact caused by water drops landing on the leaf surface,” said Dr Van Aken.
So, the researchers asked, what else can trigger such a response?
They found the same results could be produced by gently patting the plants by hand, by touching them with tweezers, or even casting a sudden shadow over the plant to limit its supply of light.
“Unlike animals, plants are unable to run away from harmful conditions. Instead, plants appear to have developed intricate stress defence systems to sense their environment and help them detect danger and respond appropriately,” said Dr Van Aken.
“Although people generally assume plants don’t feel when they are being touched, this shows that they are actually very sensitive to it and can redirect gene expression, defence and potentially their metabolism because of it”.
The study also identified two proteins that the plants used to switch off their touch response.
“Switching off the response signal is very important. It allows plants to get on with life as normal, forgetting about the signal and treating it as a false alarm” said Dr Van Aken.
“The findings may cause us to think differently about our interactions with the plants around us. While plants don’t appear to complain when we pinch off a flower, step on them or just brush by them while going for a walk, they are fully aware of this contact and are rapidly responding to our treatment of them”.