Pass the ammunition

摘要

Plants may seem passive, but in fact they respond in complex ways to diverse features of their environment. It is becoming increasingly clear, for example, that plants perceive and respond to environmental odours. However, almost nothing is known about the mechanisms by which plant olfaction occurs. Writing in Proceedings of the National Academy of Sciences, Sugimoto et al. report that when plants are exposed to odours emitted by neighbours that have been damaged by herbivorous insects, they react by transforming compounds in the odour into effective anti-herbivore defences. When insects feed on plant tissues, the assaulted plant can exhibit a range of physiological responses. For example, it may produce chemical toxins and feeding deterrents, or emit airborne volatile compounds that attract natural enemies of the feeding herbivores, such as insect predators and parasitoids (for instance, parasitic wasps, which lay their eggs in plant-feeding caterpillars). It has become widely accepted that plants can also use volatile emissions released by damaged neighbours as cues to prepare their own defences against an impending attack - an idea that had previously been controversial.