Details of the study

Most creatures that do not have the visual organs we are used to can determine where the light source is. It is useful for animals to orient themselves in the surrounding world. For plants, this is a primary task because photosynthesis depends on sunlight. Plants have even learned to rotate according to the movement of light.

The leader of the research, Professor Christian Fankhauser from the University of Lausanne, explained that scientists took two samples from the same Arabidopsis thaliana plant (gooseberry), but one of them received mutations that prevented the shoots from returning to light. At the same time, its body was transparent, unlike the wild version. It turns out that in wild plants, the color of the stem is actually determined by the presence of air in the intercellular space in various tissues of the plant, especially in the hypocotyl, which is part of the shoot stem. The mutated version contained a watery liquid instead of air.

Wild type (left) and mutant (right) Arabidopsis thaliana seedlings / Photo: CIG-UNIL

Scientists examining this interesting feature discovered the following: Light propagates differently in bodies containing liquid and air. Only in wild shoots, where air-filled tubes alternate with fluid-filled cells, does light inside the stem refract from one medium to another, creating miniature rainbows. This helps the plant understand where the light is coming from.

Also during the observations, scientists received additional data on the formation of intercellular air channels. Its functions are much broader than “vision”. For example, they promote gas exchange and at the same time make it possible to resist hypoxia, that is, a decrease in the amount of oxygen, in the event of a flood.