Plutella xylostella (L.) infestations at varying temperatures induce the emission of specific volatile blends by Arabidopsis thaliana (L.) Heynh

Abstract

The effect of combined abiotic and biotic factors on plant volatile organic compound (VOC) emissions is poorly understood. This study evaluated the VOC emissions produced by Arabidopsis thaliana (L.) Col-0 subjected to 3 temperature regimes (17, 22, and 27°C) in the presence and absence of Plutella xylostella larvae over 2 time intervals (0-4 and 4-8 h), in comparison to control plants. The analyses of VOCs emitted by Arabidopsis plants were made by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). It was found that certain volatile groups (e.g., alcohols, ketones, aldehydes, and terpenes) are induced by both single factors (temperature or larval infestation) and combined factors (temperature and larvae interactions), whereas other volatile groups (e.g., isothiocyanates [ITCs] and nitrile) were specific to the experimental conditions. ITCs (mainly 4-methylpentyl isothiocyanate) were emitted from plants subjected to larval infestation at 17 and 27°C after the 2 time intervals. The proportions of sulfides (mainly dimethyl disulfide) and 4-(methylthio) butanenitrile were significantly higher on herbivore-infested plants at 22°C compared to the other treatments. Overall, our findings indicate that changes in all experimental conditions caused significant changes to the VOC emissions of Arabidopsis plants. Therefore, the interaction between temperature and larval feeding may represent an important factor determining the variability of volatile emissions by plants subjected to multiple simultaneous factors.

Keywords: Arabidopsis thaliana; Plutella xylostella; combined factors; temperature regimes; volatile organic compounds (VOCs).

Figure 1.

Principal component analyses (PCAs) and hierarchical clustering analysis (HCA) of VOC profiles emitted by A. thaliana subjected to different temperature regimes (17, 22, and 27°C) or to temperature regimes combined with P. xylostella larval infestation (9 larvae per plant) over 2 time intervals (0–4 and 4–8 h). PCAs show the first (PC1) and second (PC2) principal components. Uninf: uninfested plants; Inf: infested plants. (A) PCA based on individual VOC relative abundances. (B) PCA and (C) HCA based on the relative proportions of each chemical family in VOC blends emitted by A. thaliana.

Figure 2.

Mean relative abundance (% ± SD; n = 3) of each VOC chemical family emitted by A. thaliana subjected to different temperature regimes (17, 22, and 27°C) or to temperature regimes combined with P. xylostella larval infestation (9 larvae per plant) over 2 time intervals (0–4 and 4–8 h). Uninf: uninfested plants; Inf: infested plants. Means sharing the same letter are not statistically different (P > 0.05, 3-way ANOVA, post hoc Tukey's HSD test).