How do plants sense stress?
How does an organism without a brain or a nervous system sense when it’s under attack? Hayley Bennett presents the plant world’s strange yet sophisticated system for responding to wounding
Being rooted to the spot, plants don’t have the luxury of running away when they’re attacked. They do have a system to deal with being eaten, but it doesn’t revolve around nerves or a brain. Say a caterpillar is munching on a leaf; the plant immediately senses the damage and mounts a response, diverting its resources from growth to defence and, for example, churning out combat chemicals destined for the caterpillar’s guts. This defence system is triggered by chemical and electrical signals, transmitted surprisingly rapidly, and their exact mechanisms have puzzled plant scientists for decades.
Faced with a lack of facts about how precisely these fast-acting plant defences operate, some outside the field have tried to claim that they must use similar mechanisms to the impulses of our own nervous systems. But without evidence to support this, and if plants don’t have nerves, or a brain, then how do they register being eaten?