Changes in the free phenolic acid composition of pepper (Capsicum annuum L.) leaves in response to green peach aphid (Myzus persicae Sulzer) infestation

Abstract

Aphids are considered one of the most damaging pests in agriculture. Plants respond to aphid attack with the production of toxic, repellent and/or antinutritive metabolites, including phenolic compounds. In this study, we examined the free phenolic acid composition of pepper (Capsicum annuum L.) leaves in response to green peach aphid (Myzus persicae Sulzer) feeding in different time course experiments. When plants were infested with an initial low density of aphids (20 aphids/plant), few significant changes were shown in leave phenolic content suggesting a very slight response from plants. However, with a high density of aphids (200 aphids/plant), several phenolics, especially the cinnamic acids (C6-C3): caffeic acid, p-coumaric acid, and sinapic acid, and also the p-hydroxybenzoic acid, salicylic acid, accumulated at specific times. Conversely, another hydroxy-benzoic acid: protocatechuic acid strongly decreased in response to infestation. The possible role of the observed changes in plant defence responses or in aphid counter-defence is discussed.