Stalk talk

You see the headline "Scientists teach spinach to send emails", and you probably think 🤔. You're right to...

No, nobody has taught the chenopodiaceous vegetable to send emails. It can't type and it doesn't have an internet connection. Not yet. But researchers in the field of "plant nanobionics" at the Massachusetts Institute of Technology (MIT) have been using spinach to detect compounds such as explosives, arsenic and nitric oxide (NO, a harmful pollutant from car engines, among other sources) in soil. When the substance enters the plant, via groundwater in the soil, the plant releases a signal, through carbon nanotubes implanted in its leaves, that can be picked up by infrared sensors. That triggers the sending of an alert by email.

This may all sound far-fetched, but Professor Michael Strano and his team at MIT have been engineering electronic systems into plants for several years. He explains: “Plants are very good analytical chemists. They have an extensive root network in the soil, are constantly sampling groundwater, and have a way to self-power the transport of that water up into the leaves.”

Strano thinks the idea can be expanded to include not only other pollutants but climate emergencies such as drought. “Plants are very environmentally responsive,” he says. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signalling pathways, there is a wealth of information to access.”