Natural variation in herbivore-induced volatiles in Arabidopsis thaliana.

To study whether natural variation in Arabidopsis thaliana could be used to dissect the genetic basis of responses to herbivory in terms of induced volatile emissions, nine accessions were characterized upon herbivory by biting-chewing Pieris rapae caterpillars or after treatment with the phytohormone jasmonic acid (JA). Analysis of 73 compounds in the headspace showed quantitative differences in the emission rates of several individual compounds among the accessions. Moreover, variation in the emission of volatile compounds after JA treatment was reflected in the behaviour of the parasitoid Diadegma semiclausum when they were offered the headspace volatiles of several combinations of accessions in two-choice experiments. Accessions also differ in transcript levels of genes that are associated with the emission of plant volatiles. The genes BSMT1 and Cyp72A13 could be connected to the emission of methyl salicylate and (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT), respectively. Overall, Arabidopsis showed interesting phenotypic variations with respect to the volatile blend emitted in response to herbivory that can be exploited to identify genes and alleles that underlie this important plant trait.