Specificity of Herbivore Defense Responses in a Woody Plant, Black Poplar (Populus nigra)

Jonathan Gershenzon,Thomas Fabisch,Sybille B Unsicker

doi:10.1007/s10886-019-01050-y

Jonathan Gershenzon, Thomas Fabisch + Show 1 more

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https://doi.org/10.1007/s10886-019-01050-y

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Abstract

The specificity of woody plant defense responses to different attacking herbivores is poorly known. We investigated the responses of black poplar (Populus nigra) to leaf feeding by three lepidopteran species (Lymantria dispar, Laothoe populi and Amata mogadorensis) and two leaf beetle species (Phratora vulgatissima and Chrysomela populi). Of the direct defenses monitored, increases in trypsin protease inhibitor activity and the salicinoid salicin were triggered by herbivore damage, but this was not herbivore-specific. Moreover, the majority of leaf salicinoid content was present constitutively and not induced by herbivory. On the other hand, volatile emission profiles did vary among herbivore species, especially between coleopterans and lepidopterans. Monoterpenes and sesquiterpenes were induced in damaged and adjacent undamaged leaves, while the emission of green leaf volatiles, aromatic and nitrogen-containing compounds (known to attract herbivore enemies) was restricted to damaged leaves. In conclusion, indirect defenses appear to show more specific responses to attacking herbivores than direct defenses in this woody plant.

Highlights

Plant chemical defenses of many types are well known to be induced upon attack by insect herbivores
Defense Hormones We assessed the levels of the defenserelated phytohormones, salicylic acid (SA) and jasmonic acid (JA), in black poplar leaves from trees of a single genotype after damage by three different herbivore species as compared to leaves from non-infested control trees
Protease inhibitor activity and salicinoids were all measured in samples collected in the same experiment, but volatiles were analyzed in a second, separate experiment

Summary

Introduction

Plant chemical defenses of many types are well known to be induced upon attack by insect herbivores. Such induction is sometimes thought to be tailored to the attacking herbivore species giving rise to terms such as the specificity of plant responses (Karban and Baldwin 1997), the specificity of elicitation (Stout et al 1998) and the specificity of induced resistance (Agrawal 2000). Recent studies have investigated whether a plant responds in an herbivore-specific manner may dependent on the feeding guild of the insect, the level of feeding specialization (reviews by Ali and Agrawal 2012; Bonaventure 2014; Heidel-Fischer et al 2014 and references therein) or salivary cues (Erb et al 2012) and herbivoreassociated microbe communities (Acevedo et al 2015).

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