Posted by: Didapper PJ7 MAR 2012
The popular “meeja” recently featured a lot of hoohah about talking cabbages. The story was that Exeter University scientists had “discovered” that cabbages chat to each other by emitting chemical messages. However, although the research was innovative, it involved neither cabbages nor the discovery of plant communication, which was already well known.
The species used in the research was a stonecress, Arabidopsis thaliana, which has the vernacular names mouse-ear cress and thale cress. The stonecress genus is certainly in the same family as the cabbages — the Brassicaceae (formerly Cruciferae) — but so are more than 330 other genera containing some 3,700 species. They include mustards, rockets, radishes, woad, alyssum, stocks, aubretias, wallflowers, honesty, candytuft and nasturtiums.
Arabidopsis thaliana is widely used in plant genetics research because it has one of the smallest genomes among flowering plants. It was the first plant genome to be sequenced, in 2000. But a stonecress is not a cabbage and it does not necessarily speak the same language as cabbages.
An injured arabidopsis plant emits methyl jasmonate, or MeJa for short, probably as a defence mechanism. Its release may deter creatures such as aphids from taking advantage of the wound or it may attract predators of such plant-munchers. Or both. But whatever its purpose, nearby plants detect the emission and produce the same chemical, thereby passing on the message.
The Exeter researchers did not discover this process. What they did was to modify A thaliana genetically to allow its chitchat to be filmed. By inserting a firefly gene into the plant’s DNA they persuaded it to produce an extra chemical, the light-emitting enzyme luciferase. Using a sensitive photon-counting camera, they could then film the plants gassing among themselves. That was their innovation.