AsianScientist (Nov. 18, 2020) – While we don’t often think plants have the ability to remember, researchers from Japan have found that the Venus flytrap can ‘store’ short-term memories through changes in the concentration of calcium ions. Their findings were published in Nature Plants.
Named after the Roman goddess of love and beauty, the Venus flytrap is the epitome of beautiful, but deadly. While its spiky, modified leaves are a sight to behold, they also form a dangerous trap. When small prey like ants or spiders land on these leaves, they activate sensory hairs found on the leaves’ inner surface.
Interestingly, the first contact with the sensory hairs has no effect. Stimulating the sensory hairs a second time in quick succession, however, triggers the leaves to clamp shut. Just like a scene from a horror movie, the flytrap’s digestive juices then fill the leafy chamber, dooming the prey trapped within. As gruesome as it may seem, all this implies that the Venus flytrap has a way to store memories of that first encounter. But how can the flytrap remember without a brain?
Over three decades ago, in 1988, German scientists speculated that calcium ions may be involved in the Venus flytrap’s memory. After all, calcium ions play a crucial role in cell signalling. At the time, however, they lacked the technology to measure calcium ion concentration without damaging the plant’s cells.
Fast-forward to 2020 and scientists now have the means to do so. With the help of a fluorescent protein, researchers from Japan’s National Institute for Basic Biology (NIBB) have demonstrated that the Venus flytrap’s short-term memory does indeed result from changes in calcium ion concentration.
They did this by first introducing a gene that codes for the sensor protein GCaMP6 into the plant. When bound to calcium ions, GCaMP6 emits a green fluorescence, allowing the team to visualize changes in calcium ion concentration within the Venus flytrap’s cells.
The researchers then tapped the flytrap’s sensory hair with a needle, measuring the resulting changes in the calcium ion levels. The first stimulus triggered the release of calcium ions, with each successive stimulation increasing ion concentration within the leaf’s cells. Once the concentration exceeded a certain threshold—typically as a result of the second stimulus—the trap closed.
Because calcium ion concentrations decrease over time, the authors observed that the second stimulus must occur within 30 seconds. Otherwise, the trap remained open. Therefore, the rise and fall of calcium ion concentrations in the Venus flytrap’s leaf cells allows the plant to have some form of short-term memory. In doing so, the Venus flytrap can easily tell wriggling prey apart from a drop of rain.
“This is the first step towards revealing the evolution of plant movement and carnivory, as well as the underlying mechanisms. Many plants and animals have interesting but unexplored biological peculiarities.” said Professor Mitsuyasu Hasebe from NIBB, who led the research team.
The article can be found at: Suda et al. (2020) Calcium Dynamics During Trap Closure Visualized in Transgenic Venus Flytrap.
Source: National Institute for Basic Biology; Photo: Pexels.
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