Print PageThe emission of plant volatiles induced by mechanical wounding, herbivory, or chemical elicitation allows for plant-to- plant and plant-to-insect communication. Plant volatiles are specific to the species of plant and also to the type of stimuli the plant receives. In our study we determined the composition of volatile profiles released by Arabidopsis thaliana plants (Wassilewskija ecotype) in response to mechanical wounding and two species of caterpillars: Pieris rapae, a specialist on the plant family Brassicaceae and Spodoptera exigua, a generalist feeder. We used a flow-through volatile collection system with adsorbent traps to capture volatiles and analyzed them using GC-MS. Using available standards, we developed a method to detect and quantify 19 volatile organic compounds commonly produced by plants, and several other compounds by relative quantitation.
Results/Conclusions
We found treatment-specific responses in volatile profiles associated with both the amount and kind of damage produced. We demonstrated specificity in VOCs of Arabidopsis responding to two caterpillars and mechanical wounding. Methyl salicylate (MeSA) was increased 2-4 fold by S. exigua compared to that elicited by P. rapae (P<0.0001). Average levels of hexenal and hexanol were also increased 4 fold by S. exigua but the differences were not statistically significant at this sample size (n=9). The strong elicitation of MeSA by S. exigua has important implications for plant resistance. MeSA attracts natural enemies of caterpillars causing higher rates of parasitism and changes in leaf defense chemistry. Our long-term goals are to investigate the molecular basis of plant-to-plant communication and continue work with bioengineers to develop a more sensitive GC capable of detecting plant volatiles outdoors.
