The plant kingdom is composed of living beings that have been a fundamental part in shaping the present life in the world. Without plants, it would not have been possible the massive production of oxygen that is now in the atmosphere, all generated from carbon dioxide, which allowed the emergence of other classes of multicellular beings such as animals. In addition, they are the main source of food for many organisms.

Plants have the capacity to grow as well as to feel, even if they do not do so in the same way as animals, nor do they experience pain. They can detect changes on the outside and “learn” from these experiences. For example, there is phototropism, which is the ability to direct growth in the direction of light rays. But, can plants present a similar sense to vision as humans? This is an idea that has been denied outright by scientists for decades, but recent studies provide data against this belief.

The possible vision of plants

The hypothesis that plants have the capacity for vision is not new. Already in 1907, the botanist Francis Darwin , son of the naturalist and father of the theory of evolution Charles Darwin, thought about it. Known for his studies on phototropism mentioned above, Francis let it be known that there could be an organ formed by the combination of a cell that acts as a lens and another that presents sensitivity to light, offering the characteristic of seeing.

Experiments at the beginning of the 20th century proved the existence of an organ we know today as the ocelus, or simple eye , but which is present in invertebrates and not in plants. Therefore, the idea of vision in plants fell into oblivion … until the end of last year, when with the emergence of a new line of research the idea was revived.

A bacterium with sight

In a recent publication of the medium Trends in Plant Science by Franti?ek Balu?ka, a plant cell biologist from the University of Bonn in Germany, and Stefano Mancuso, a plant physiologist from the University of Florence in Italy, there is new evidence that plants may indeed see.

The first point the researchers make is that in 2016 it was discovered that the cyanobacterium Synechocystis has the ability to act like an ocelus . Cyanobacteria, which were previously also called blue-green algae, form a biological category (a phylum) comprising single-celled organisms that have the ability to perform photosynthesis. Being prokaryotic cells, it is wrong to consider them as algae, a term that is limited to only a few eukaryotic cells.

The mechanism that Synechocystis uses to generate vision is based on a curious trick: uses its own body as if it were a lens to project an image of the light that arrives through its cell membrane, just as the retina does in animals. Balu?ka believes that if this ability exists in such primitive beings, there may be a possibility of a similar mechanism in higher plants.

Other evidence in favour

Other points highlighted by these researchers are based on recent studies that reveal that some plants, such as cabbage or mustard, make proteins that are involved in the development and functionality of the eye spot or stigma, a very simple kind of eye that is present in some single-celled organisms such as green algae, which allow them to capture information regarding the direction of light.

These proteins are specifically part of the structure of the plastolobes , vesicles that are found inside the chloroplast (cellular organelle in charge of photosynthesis) and whose function is a mystery. Baluška suggests that this discovery may reveal that plastoblobs act as an eye spot for higher plants.

Other observations made by researchers, drop the idea that the vision capacity of plants may use totally different systems to what we currently know in complex organisms, being for the moment out of our comprehension. For example, in 2014 a study appeared showing that the vine plant Boquila trifoliolata can modify the colour and shape of its leaves, imitating those of the plant that supports it. It is not known what mechanism it uses to achieve this mimicry.

In spite of all that has been said, in the end this is evidence and not a description of the concrete mechanism that the plants would use to see. In spite of this, it opens the door to a new path of investigation around plant physiology and biology in search of whether there really can be one or different methods of capturing visual information from the environment, a resource that would allow superior plants to possess a sense of vision, just as a bacterium like Synechocystis does.