Infestation with chewing (Spodoptera frugiperda) and piercing-sucking (Tetranychus urticae) arthropod lead to differential emission and biosynthesis of HIPVs underscoring MeSA and terpenoids in chrysanthemum foliage

Many volatiles that are induced in plant foliage as a result of herbivorous insect infestation can act as cues for natural enemy attraction or for priming defense mechanisms. However, the qualitative and quantitative differences in volatile emissions in chrysanthemum plants that are fed upon by pests with different mouthparts have not been explored. In this study, Tetranychus urticats (TEU) with piercing-sucking mouthparts and Spodoptera frugiperda larvae (FAW) with chewing mouthparts were selected to infest the Chrysanthemum morifolium leaves to determine the response of volatile emission and production induced by herbivore feeding with different mouthparts. Our results showed that FAW-infestation significantly increased the emission rate of monoterpenes and specifically induced the emission of 13-pinene. In contrast, TEU-infested plants significantly enhanced the emission rate of sesquiterpenes and phenylpropanoids compared to the control group. In particular, 13-funebrene and methyl salicylate (MeSA) were exclusively induced in TEU-infested plants. CmSAMTs responsible for the elicited emission of MeSA, were functionally characterized. Additionally, multiple CmTPSs with strikingly elevated expression induced by TEU and FAW-infestation were subjected to enzymatic assay for the identification of their biochemical function. The products (13-pinene, a-copaene, germacrene D, 13-caryophyllene, 13-funebrene and 13-ylangene) of two pivotal CmTPSs covered the major terpene profiles elicited by TEU and FAW feeding. Overall, these results could deepen our understanding of the corresponding defensive strategies against herbivores feeding with different mouthparts in chrysanthemum plants and provide theoretical basis for the biological control of pests in the cultivation and production of chrysanthemum.