They have a surprising characteristic in their fabrics. It allows them to detect directional light signals. How do plants follow light? Now we know.
It is a plant tissue sensitive to light. It generates a “visible” light gradient for the plant, according to what its authors publish in the journal ‘Science’. Most living organisms can determine the origin of a light source. Even in the absence of an organ of sight comparable to the eye. Why is it important for plants? Because it allows them to position their organs, a phenomenon known as phototropism. This way they capture the sun’s rays better. This is converted into chemical energy through the process of photosynthesis.
Mutant species
It all started with the observation of a mutant of the model species ‘Arabidopsis thaliana. Its stem was surprisingly transparent. These plants did not respond correctly to light. The biologists compared the optical properties of the mutant samples against the wild ones.
The natural milky appearance of wild plant stems has a reason. It is due to the presence of air in precisely located intercellular channels in various tissues. In the mutant samples, the air is replaced by an aqueous liquid. This gives them a translucent appearance.
These air-filled channels allow the photosensitive stem to establish a gradient of light that the plant can “read.” Thus, the plant can determine the origin of the light source. This phenomenon is due to the different optical properties of air and water, which make up the majority of living tissues.
Following the light
This determined how plants follow light. «Air and water have different refractive indices. This causes the dispersion of light as it passes through the seedling. We have all observed this phenomenon when admiring a rainbow,” the researchers explain in a statement.
This novel mechanism allows living organisms to perceive where light comes from. In this way, it arranges its leaves so that the capture of light for photosynthesis is optimized. Air-filled intercellular channels have various functions in plants, in addition to the formation of light gradients. Among other uses, these channels promote gas exchange. They also allow them to resist hypoxia (reduction in the amount of oxygen) in the event of flooding.
