Herbivore‐induced volatiles influence moth preference by increasing the β‐Ocimene emission of neighbouring tea plants

Abstract

Herbivore-induced plant volatiles prime neighbouring plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this state and their priming mechanisms remain largely unknown. The tea geometrid Ectropis obliqua is one of the most devastating leaf-feeding pests of tea plants. Here, plant-plant communication experiments demonstrated that volatiles emitted from tea plants infested by E. obliqua larvae triggered neighbouring plants to release volatiles that repel E. obliqua adult, especially mated females. Volatile analyses revealed that the quantity of eight volatiles increased dramatically when plants were exposed to volatiles emitted by infested tea plants, including (Z)-3-hexenol, linalool, α-farnesene, β-Ocimene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT). The results of behavioural bioassays demonstrated that β-Ocimene strongly repelled mated E. obliqua females. Individual volatile compound exposure experiments revealed that (Z)-3-hexenol, linalool, α-farnesene and DMNT triggered the emission of β-Ocimene from tea plants. Chemical inhibition experiments demonstrated that the emission of β-Ocimene induced by (Z)-3-hexenol, linalool, α-farnesene and DMNT were dependent on Ca 2+ and JA signalling. These findings help us to understand how E. obliqua moths respond to volatiles emitted from tea plants and provide new insight into volatile-mediated plant-plant interactions. They have potential significance for the development of novel insect and pest control strategies in crops. K E Y W O R D S calcium (Ca 2+ ), HIPVs, JA, mated moth, MPK signalling, tea plant 1 | INTRODUCTION As sedentary organisms, plants are under constant threat of attack from herbivores and pathogens. Throughout development, plants must adapt to their surroundings and respond to diverse environmental stimuli in ways that influence their interactions with other organisms. Thus, plants have evolved a broad range of surprisingly sophisticated mechanisms that allow them to deal with biotic and abiotic stressors (Conrath, Tingting Jing and Xiaona Qian contributed equally to this work.

Undercover operation: Belowground insect herbivory modifies systemic plant defense and repels aboveground foraging insect herbivores

“…Alternatively, (E)-β-ocimene alone could serve as a direct defense and repel aboveground foraging herbivores. Recent evidence from tea plants demonstrated β-ocimene emissions enhance plant resistance to foraging herbivores (Jing et al, 2021). For our study, to test the hypothesis that (E)-β-ocimene directly repels herbivores, we conducted dual-choice preference bioassays with β-ocimene-dispensers and found mixed support for (E)-βocimene serving as a direct defense.…”

Evaluation of Selected Plant Volatiles as Attractants for the Stick Tea Thrip Dendrothrips minowai in the Laboratory and Tea Plantation

“…Twenty types of compounds, derived from tea plants and plant-derived semiochemicals attracted to other thrips, were used in our trials [ 4 , 24 , 25 , 26 ]. In particular, 4-acetylpyridine, p-anisaldehyde, decanal, eugenol, farnesene (mixture of isomers, α-farnesene, and (E)-β-farnesene), geraniol, (Z)-3-hexenol, (Z)-3-hexenyl butyrate, limonene, methyl anthranilate, methyl benzoate, 3-methyl butanal, methyl isonicotinate, methyl salicylate, β-myrcene, nonanal, (E)-β-ocimene, (−)-α-pinene, (+)-α-pinene, and γ-terpinene were all purchased from Sigma-Aldrich (St. Louis, MO, United States) ( Table S1 ).…”

“…Both adults and nymphs of D. minowai feed on the leaflet of tea plants, causing stunted growth, color fading, and even stiffness or brittleness of the damaged leaves, which seriously affect the yield and quality of tea [ 23 ]. An array of tea plant volatiles is used by herbivores for host searching and locating, and several of these compounds have been investigated as non-pheromonal attractants to improve the capture of pests [ 24 , 25 , 26 ]. For instance, (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, and linalool are volatiles derived from tea plants and significantly attract Empoasca onukii adults [ 27 ].…”

Calcium Signaling in Plant-Insect Interactions

“…GLVs emitted by herbivore-wounded tomato (including ( Z )-3-hexenyl acetate) were found to induce a strong [Ca 2+ ] cyt increase in receiving plants [ 59 ]. The emission of β-ocimene induced by ( Z )-3-hexenol, linalool, α-farnesene and ( E )-4,8–dimethyl–1,3,7-nonatriene (DMNT) (which are typical VOCs emitted upon herbivory) were dependent on Ca 2+ signaling [ 60 ]. H 2 O 2 and [Ca 2+ ] cyt increased in Arabidopsis mesophyll cells after being treated with the volatile monoterpene alcohol linalool in the attempt to increase plant resistance to diamondback moth ( Plutella xylostella ) [ 61 ].…”