Plant-herbivore interactions: experimental demonstration of genetic variability in plant-plant signaling

Abstract

Plant-herbivore interactions mediated by plant-plant signaling were documented in different species. Here, we tested if herbivore foraging activity on plants was influenced by plant's prior contact with a damaged plant and if the effect of such plant-plant signaling was variable across genotypes. We filmed snails during one hour on two plants differing only in a prior contact with a damaged plant or not. We replicated eight times the experiment on 113 natural genotypes of Arabidopsis thaliana. We recorded snails' first choice, and measured its first duration on a plant, the proportion of time spent on both plants and leaf consumption. On average, snails spent more time on plants that experienced a prior contact with a damaged plant, and consumed them more. However, plant-plant signaling effect on snail behavior was variable across genotypes. Genome-wide association studies revealed that a small number of genetic polymorphisms related to stress coping ability and jasmonate pathway explained this variation. Plant-plant signaling modified the foraging activity of herbivores in A. thaliana. Depending on the plant genotype, plant-plant signaling made undamaged plants more repulsive or attractive to snails. This finding questions the theoretical basement of the evolution of plant-herbivore interactions mediated by plant-plant signaling.