Abstract:

The signal transfer between plants was mediated by compound signals composed of different volatiles. In order to explore the action mode of compound signals, one-year-old poplar(Populus simonii×P. pyramidalis ‘Opera 8277’) cuttings were exposed to four mixed volatiles, I.e. methyl jasmonate(MeJA) + methyl salicylate(MeSA), MeJA + cis-hexenal, MeJA + trans-hexenal, MeJA + benzothiazole, and then the induced activities of three defensive enzymes including peroxidase(POD), polyphenol oxidase(PPO) and phenylalanine ammonia lyase(PAL) were measured. The results showed that all of four mixed volatiles exposure resulted in higher activities of POD, PPO and PAL than only single volatile treatment in intact poplar leaves, indicating that mixed volatiles possessed stronger inducing capability. Moreover the synthetic inducing effect of mixed volatiles was more than the sum of individual volatiles. Among these four mixed volatiles, MeJA + cis-hexenal exhibited the highest inducing capability.

Key words: Populus simonii×, P. pyramidalis &lsquo, Opera 8277&rsquo, mixed volatiles, compound signal, defense response, activities of defensive enzymes