A fascinating study led by researchers from Washington State University has revealed that plants can sense when they are being touched and when the touch is released, despite not having nerves like animals.
The study involved experiments on individual plant cells, which responded to the touch of a delicate glass rod by sending signals to other cells.
The researchers observed that when the pressure of the touch was applied, slow waves of calcium signals were sent among the cells. However, when the pressure was released, the cells sent much more rapid waves.
This finding demonstrates that plants can distinguish between the initiation and ending of touch.
The research team conducted numerous experiments using specially bred thale cress and tobacco plants that contained calcium sensors, enabling them to observe the plants’ responses under a microscope.
By gently touching individual plant cells with a tiny glass rod, they observed various complex responses based on the force and duration of the touch. However, the most significant distinction was seen between the touch and its removal.
Within 30 seconds of the touch, the researchers noticed slow waves of calcium ions traveling from the touched cell to the neighboring plant cells. These waves lasted for approximately three to five minutes.
On the other hand, the removal of the touch triggered a rapid series of waves that quickly dissipated within a minute.
The researchers believe that these waves are a result of changes in pressure inside the plant cells. Unlike animal cells, plant cells have sturdy cellular walls that cannot be easily penetrated. Therefore, even a light touch can temporarily increase the pressure within a plant cell.
To support their theory, the scientists mechanically tested the pressure concept by inserting a tiny glass probe into a plant cell.
They found that manipulating the pressure inside the cell produced similar calcium waves as those triggered by the initiation and cessation of touch.
In contrast to animals that rely on specialized sensory cells for touch perception, plants seem to sense touch through fluctuations in internal cell pressure. This mechanism is present in all plant cells on the surface, not just specific sensory cells.
Previous research has demonstrated that plants can respond to touch by activating defensive measures against pests, such as releasing chemicals that make the leaves less appealing or even toxic.
Additionally, brushing or touching a plant can generate calcium waves that activate various genes.
While this study successfully differentiated between calcium waves associated with touch and those associated with the release of touch, the exact response of plant genes to these signals requires further investigation.
With advanced technologies like the calcium sensors used in this study, scientists can delve deeper into unraveling this mystery.
This groundbreaking research highlights the remarkable abilities of plants and deepens our understanding of their sensory perception.
It opens up exciting avenues for future studies to explore how plants utilize touch signals and how they influence various biological processes within the plant kingdom.
