Application of chemical elicitor (Z)-3-hexenol enhances direct and indirect plant defenses against tea geometrid Ectropis obliqua

Plants can respond to herbivorous attack with induced defense mechanisms. Plant elicitors play vital roles in inducing the plant defense response against herbivores. In this study, we investigated the effect of (Z)-3-hexenol (z3HOL), an important component of green leaf volatiles (GLVs), on the induced defense against a tea geometrid (TG) Ectropis obliqua Prout in tea plants. We showed that treatment with z3HOL elicites increased levels of jasmonic acid (JA) and ethylene (ET) as well as of expression of a lipoxygenase gene CsiLOX1 and a putative ACC synthase gene CsiACS1. Such reactions resulted in a marked increase in polyphenol oxidase (PPO) activity and volatile production. The induced tea plants reduced the performance of TG and became highly attractive to the main parasitoid wasp, Apanteles sp. These findings suggest that z3HOL can serve as an elicitor that triggers direct and indirect defense responses against TG by modulating signaling pathways in tea and provide a friendly strategy for biological control of pests.