Looking at your garden, enjoying all the different colors and smells that the plants send out, did you ever imagine that these scents could be camouflaged messages? Say like, a message to attract pollinators to them?
Plants just as other living beings, are able to communicate with each other and even with themselves. For a plant to survive, it is necessary to send signals to perform the different physiological functions like photosynthesis, transpiration and water uptake in the roots. However, some of these signals occur externally as well, through volatile airborne signals called volatile organic compounds or VOCs.
These VOCs consist of a very diverse family of organic compounds such as aldehydes, esters, alcohols etc. These compounds can be produced under normal growth conditions or under stress conditions such as leaf damage. They are characterized for being very volatile at room temperature and have a high diffusion rate, allowing for a signal to be propagated over relatively long distances from the emission point.
VOCs are affected by a variety of factors, such as temperature, which determines rates of volatilization and growth, and sunlight, which determines rates of biosynthesis. Plants have small pores on their surface that allow for gas exchange with the environment. These pores are known as stomata and have a vital role in the plant’s growth and development, a subject that can occupy a whole blog entry on its own. These stomata act as a gateway for VOC emission, allowing for these substances to be released to the environment. Moreover, these stomata also act as an entryway of VOCs into the plant, successfully playing a role of emissary and receptor.
So, when will plants use these VOCs? Scientists have observed that plants can call for help when they are being attacked. It has been observed that plants being eaten by a specific insect can send out signals to attract predators of that insect thus saving themselves from further attacks.
Plants can also listen for messages from their neighbors to protect themselves from an imminent attack. When a plant is in distress, it sends out a message mainly to warn nearby leaves about the damage being produced so that they can increase their defenses and fight of the stress. However, many plants eavesdrop on these conversations and protect themselves as well. So, the next time you’re enjoying the scent of freshly cut grass, know that these are the distress signals the grass is sending out!
Plants also recognize their nearby siblings. A study on sea rocket have shown that plants grown in pots with other species, had more root growth to better compete for nutrients whereas plants grown with the same species, had limited root growth to share all the resources, a definite considerate and family oriented move.
Plants may seem as sessile and boring beings but they are much more complicated than that, plants dance with the wind, they send out beautiful scents to attract pollinators and even have a social life. If the few plants in our gardens have short conversations, imagine what happens in a forest!
By Abbas Caballero