Studies show signs that plants may know their environment better than we think.
The vegetable kingdom is composed of living beings that have been a fundamental piece in shaping the current life present in the world. Without plants, the massive production of oxygen that is now found in the atmosphere would not have been possible, all generated from carbon dioxide, which allowed the appearance of other kinds of multicellular beings such as animals. In addition, they are the main source of food for many organisms.
Plants have the ability to grow as well as to feel, although they do not do it 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 of vision like humans? This is an idea na idea flatly denied by scientists for decades, but recent studies provide data against this belief.
The possible vision of plants
The hypothesis that plants have the ability of vision is not new. As early as 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 the aforementioned phototropism, Francis dropped that there could be an organ that was formed by the combination of a cell that acts as a lens and another that has sensitivity to light, offering the characteristic of seeing.
Experiments from the beginning of the 20th century confirmed the existence of an organ that we know today as the ocellus, or simple eye, but which is present in invertebrates and not in plants. For this reason, the idea of vision in plants fell into oblivion … until the end of last year, at which time, with the appearance of a new line of research, the idea was revived.
A bacterium with a view
New evidence appears in a recent publication by Trends in Plant Science by František Baluška, a plant cell biologist at the University of Bonn in Germany, and Stefano Mancuso, a plant physiologist at the University of Florence in Italy, new evidence appears that plants may yes see.
The first point that the researchers make is that in 2016 it was discovered that the cyanobacterium Synechocystis has the ability to act as an ocellus. Cyanobacteria, which were previously also called blue-green algae, form a biological category (a phylum) that comprises single-celled organisms that have the ability to photosynthesize. Being prokaryotic cells, it is wrong to consider them as algae, a term that is limited only to some eukaryotic cells.
The mechanism that the Synechocystis uses to generate vision is based on a curious trick: it uses its own body as if it were a lens to project an image of the light that reaches through its cell membrane, just as the retina does in the animals. Baluška believes that if this ability exists in such primitive beings, it may be that in higher plants there is a possibility that they present a similar mechanism.
Other evidence in favor
Other points that these researchers highlight are based on recent studies that reveal that some plants, such as cabbage or mustard, manufacture 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 unicellular organisms such as green algae, which allow us to capture information regarding the direction of light.
These proteins are specifically part of the structure of plastoglobules, vesicles that are found inside the chloroplast (cellular organelle responsible for photosynthesis) and whose function is a mystery. Baluška suggests that this discovery may reveal that plastoglobules act as an eye spot for higher plants.
Other observations made by researchers, drop the idea that the vision capacity of plants may use systems totally different from what we currently know in complex organisms, being for the moment beyond our understanding. For example, in 2014 a study appeared that showed that the Boquila trifoliolata creeper plant can modify the color and shape of its leaves, imitating those of the plant that supports it. The mechanism used to achieve this mimicry is unknown.
Despite all that has been said, at the end of the day it is evidence and not a description of the specific mechanism that plants would use to see. Despite this, the door opens to a new path of research around plant physiology and biology in search of whether there really can be one or different methods to capture visual information from the environment, a resource that would allow higher plants to possess meaning of vision, as does a bacterium such as Synechocystis.