Insects (Thrips hawaiiensis (Morgan)) change the stereochemical configuration of 1-phenylethanol emitted from tea (Camellia sinensis) flowers

Insect attacks change the quantity of volatiles emitted from plants, but little is known about the effects on the volatiles' stereochemical configurations. 1-Phenylethanol (1PE) is a major internal volatile of tea (Camellia sinensis) flowers. In the present study, insect-damaged C. sinensis flowers in the field emitted a different (R)-/(S)-1PE pattern than that emitted from undamaged flowers. Laboratory experiments showed that changes in the (R)-/(S)-1PE ratio were caused by treatments with Thrips hawaiiensis (Morgan), a pest of cut flowers and vegetable crops. These treatments led to an increase in jasmonic acid (JA) through the activation of allene oxide synthase, which is involved in JA biosynthesis. Exposing flowers to exogenous JA induced an (R)-/(S)-1PE emission pattern that was similar to that induced by a T. hawaiiensis attack, suggesting that JA was involved in the changes in the stereochemical configuration of 1PE emitted from the flowers after insect treatments. This study provides new insights into the involvement of volatiles in interactions between plants and insects, showing that not only the quantity but also the stereochemical configuration of plant volatiles is affected by insects.