If we could know what the plants speak

Although we may often forget it, plants are an essential part of human life. They provide us with food, both directly and indirectly. Humans alone devour over 7,000 species of plants, with cereals such as wheat, maize and rice and crops such as potatoes and legumes an essential part our diets.

Plants regulate the air we breathe. Our oxygen is a by-product of photosynthesis, and plants absorb the Co2 we create by burning fossil fuels. Although, recent research, published in Atmospheric Chemistry and Physics Discussions, focused on the impact of global air, predicting that future ozone levels could be high enough to cause serious damage to plants and crops, even if emissions of greenhouse gases are reduced.

Our conventional medicines such as morphine, aspirin and quinine are derived from plants, and Fungi have also revolutionised medicine, with examples including antibiotics such as penicillin and immunosuppressant and cholesterol drugs.

With plants playing such a major role in our everyday lives, it’s unsurprising that they are still a source of much fascinating research for scientists worldwide. Most recently, a team of European researchers have been pushing the boundaries of plant research in order to establish what plants talk about and what they can tell us about the environment.

A network of microsensors that can be embedded in plants to send information about plants’ response to environmental changes such as humidity, temperature, pollution and exposure to chemicals, are being developed by British, Spanish and Italian researchers. These microsensors will allow researchers to analyse signals transmitted by plants and draw conclusions about what the plant is communicating about its environment. The project, Plants Employed As Sensing Devices (PLEASED), has raised EU funding of over a million euros to date.

Speaking about the project, researcher Stefano Mancuso said, “A digital network and a powerful algorithm transforms each tree into an environmental informer. A single tree will be able to give information about several environmental parameters simultaneously. But using traditional sensors, as is currently the case in environmental monitoring stations, means using one sensor for each parameter, which is very expensive.”

The fact that plants have a means of communicating with each other is not a recent discovery, and this project is not the first of its kind. Others, such as the PLANTOID project, have combined plants and technology by creating ‘robots’ that imitate plant behaviour to gather information by soil monitoring and exploration.

However, a major advantage of the project is the accessible and low-cost technology used, and that the data collected will be readily available on a global scale. This means that anyone interested in the project can make sensors to use on their own plants, contribute their own findings to a database and get access to researchers’ findings, whether they want to research the effects of changing temperatures or of certain chemicals on their plants.

Plants feel pain, say some scientists. Every stroke of those pruning shears could have the average shrub writhing in agony. Researchers in Bonn, Germany, found plants give off a gas when under ‘attack’.

Super-sensitive microphones picked up a ‘bubbling’ sound from a healthy plant. But this rose to a piercing screech when it was under threat. Even a tiny insect bite could have an effect.

‘The more a plant is subjected to stress, the louder the signal,’ said Dr Frank K¸hnemann.

Plants do not actually scream in pain. But different sounds are heard when the gas they emit, ethylene, is bombarded with lasers.

The research could help to work out which pieces of fruit and vegetables are likely to stay fresh longer, as a cucumber which is starting to go off produces a squealing sound. It could then be separated from the fresher ones.

Fruit exporters are already showing interest in the research. Wolfgang Praetorius, of Cologne- based Fruchthansa, said: ‘Individual pieces of fruit could be tested after being harvested. We’d know which ones to ship together.’

In another new study conducted by Dr. David Johnson at the University of Aberdeen found that plants communicate with one another through the soil. The study shows that when vegetables are infected with certain diseases, they alert other nearby plants to activate genes to ward off the disease when it heads their way. The key to this communication is a soil fungus that acts as a messenger.

Soil fungus and certain plants have a symbiotic relationship, according to the research team, who shared their findings with The Economist. The plants deliver food and the fungus delivers minerals. But now it turns out the fungal hyphae, which creates a network in the soil that connects the various plants, plays another essential role as a messenger.

In 2010, a team of Chinese researchers found that when a tomato plant became infected with a leaf blight, it was able to somehow alert nearby tomato plants, which then prepared their defense. Dr. David Johnson and his team sought to find out by which mechanism the plants were able to communicate this information with Broad Bean plants.

To prove that the plants were communicating through the soil, the team set up a series of “mesocosms” of five bean stalks each. Beans are often attacked by aphids. When this happens, they release a chemical that attracts wasps that then come around and annihilate the aphids.

“Five weeks after the experiment began, all the plants were covered by bags that allowed carbon dioxide, oxygen and water vapour in and out, but stopped the passage of larger molecules, of the sort a beanstalk might use for signalling. Then, four days from the end, one of the 40-micron meshes in each mesocosm was rotated to sever any hyphae that had penetrated it, and the central plant was then infested with aphids.”

You can read more about the experiment at The Economist, but the controls demonstrated that indeed the bean plants communicated to each other through the soil when it was found that one of them had been attacked by aphids!

Source Credits: Environmental Technology Online, Daily Mail UK, Tafline Laylin in Inhabitat

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