Nano Girl Michelle Dickinson: Plants talking to scientists

Plants can notice small changes in the properties of soil and can help predict if there is going to be drought or if there is an accumulation of chemicals in the groundwater. Pictures / 123RF
Plants can notice small changes in the properties of soil and can help predict if there is going to be drought or if there is an accumulation of chemicals in the groundwater. Pictures / 123RF

Some gardeners are convinced that the act of talking to plants will help them to grow faster and healthier, but what if your plant could help to tell you information about your environment?

Phytoremediation is the low cost, solar powered clean-up process which uses living plants to remove contaminants including nitrogen, inorganics and heavy metals held in soils, surface and groundwater.

Plants naturally draw up water and minerals through their roots, which will eventually absorb in their leaves or stem through a process called transpiration.

Phytoremediation is often used to slow the movement of contaminated groundwater and can help prevent excess agriculture produced nitrogen run-off from entering the waterways.

As hyperaccumulators, some plants including sunflowers, spinach and radish are good plants to use as they can take up large amounts of toxic materials from their environment.

For example, sunflowers were planted around the Chernobyl region after the nuclear disaster to help remove some of the radioactive isotopes trapped in the soil there.

Once enough material has accumulated in the plant, the whole plant can be pulled out of the soil, easily removing the contaminant in a solid form and enabling it to be disposed of appropriately.

This week, scientists in the US have taken phytoremediation one step further by combining it with nanobionics - the process of modifying biology with engineering.

By injecting the plant leaves with carbon nanotubes, tiny tubes of carbon which are 2000 times thinner than the width of human hair, they can transform the leaves into sensors for the toxin of interest.

The plant can now indicate if the toxin is present in the ground where it is planted while simultaneously being active in removing it.

The MIT researchers used carbon nanotubes that can detect nitro-aromatic compounds, which are often used in landmines and other explosives and injected them into the leaves of spinach plants. If the chemical was present in the soil groundwater where the spinach was planted it would naturally absorb it causing the nanotubes in the leaves to emit a near-infrared fluorescent light which glows when a laser is shone onto the leaf.

When viewed using an infrared camera the fluorescent light can be detected and a camera can be set up to watch the plants for any signs of the toxin being absorbed. By attaching the camera to a smartphone or cheap Raspberry Pi computer, the system can be set up to e-mail the user and tell them that the toxin has been detected.

The researchers had previously created similar nanobionics experiments for the detection of nitric oxide which is a pollution produced by combustion as well as the nerve gas sarin and the explosive TNT.

Plants are cheap and give real-time information as they are so environmentally responsive making nanobionic phytoremediation and incredibly powerful tool for chemical detection. Their natural sensitivity means that they notice small changes in the properties of soil and can help predict if there is going to be drought or if there is an accumulation of chemicals in the ground water.

By being able to tap into the chemical pathways of a plant, they can almost talk to us about the environment they are in. If only Popeye had known about the extra superpowers that could have been added to his daily intake of spinach.

- NZ Herald

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