Communication between plants: induced resistance in poplar seedlings following herbivore infestation, mechanical wounding, and volatile treatment of the neighbors

Abstract

AbstractThe possibility of communication between plants was proposed over 25 years ago, although previous demonstrations have suffered from methodological problems and have not been widely accepted. Micromelalopha troglodyta (Graeser) and Clostera anastomosis (L.) (both Lepidoptera: Notodontidae) are important leaf‐feeding insects on poplars (Populus spp.; Salicaceae). There is no report of M. troglodyta‐ or C. anastomosis‐induced plant–plant communication up to now. To understand the regulatory mechanism of poplar defense responses, the specific activities of the presumed anti‐herbivore enzymes phenylalanine ammonia lyase (PAL), lipoxygenase (LOX), polyphenol oxidase (PPO), and peroxidase (POD) were determined in poplar seedlings treated with herbivore infestation and volatiles, artificially damaged seedlings, and intact healthy poplar seedlings growing nearby. The expression levels of PPO, POD, PAL, and LOX were elevated in poplar seedlings treated by herbivore infestation, mechanical wounding, methyl jasmonate, methyl salicylate, or benzothiazole. Furthermore, plants neighboring the treated poplar seedlings also showed increased expression levels of PPO, POD, PAL, and LOX relative to the control. These induced responses against feeding injury, mechanical wounding, and volatile treatment in expression levels of PPO, POD, PAL, and LOX suggest interplant communication between poplar seedlings.