Herbivore-derived fatty-acid amides elicit reactive oxygen species burst in plants.

Reactive oxygen species (ROS) can be elicited by many forms of stress, including pathogen attack, abiotic stress, damage and insect infestation. Perception of microbe- or damage-associated elicitors triggers an ROS burst in many plant species; however, the impact of herbivore fatty-acid amides on ROS elicitation remains largely unexplored. In this study we show that the lepidopteran-derived fatty-acid amide elicitor N-linolenoyl-L-glutamine (GLN18:3) can induce a ROS burst in multiple plant species. Furthermore, in Arabidopsis this ROS burst is partially dependent on the plasma membrane localized NADPH oxidases RBOHD and RBOHF, and an Arabidopsis rbohD/F double mutant produces enhanced GLN18:3-induced jasmonic acid. Quantification of GLN18:3-induced ROS in phytohormone-deficient lines revealed that in Arabidopsis reduced levels of jasmonic acid resulted in a larger elicitor-induced ROS burst, while in tomato reduction of either jasmonic acid or salicylic acid led to higher induced ROS production. These data indicate that GLN18:3-induced ROS is antagonistic to jasmonic acid production in these species. In biological assays, rbohD/F mutant plants were more resistant to the generalist herbivores Spodoptera exigua and Trichoplusia ni but not to the specialist Plutella xylostella. Collectively, these results demonstrate that in Arabidopsis herbivore-induced ROS may negatively regulate plant defense responses to herbivory.