Chiral Chemopolymorphism in the Monoterpenes of Pistacia palaestina Leaves and Galls

Abstract

ABSTRACTPistacia palaestina Boiss. is a common tree in the Mediterranean maquis. The leaves of this plant accumulate defensive monoterpenes, whose levels greatly increase in galls induced by the aphid Baizongia pistaciae. We previously found a significant chemopolymorphism in monoterpene content among individual trees, but the chirality of these monoterpenes was unknown. Although most plant species specifically accumulate one enantiomeric form of a given compound, P. palaestina individuals display chemopolymorphism in the chirality of the key monoterpenes accumulated. We report here a marked enantiomeric variation for the limonene, α‐ and β‐pinene, camphene, sabinene, δ‐3‐carene, and terpene‐4‐ol content in leaves and galls of nine different naturally growing P. palaestina trees. Interestingly, insect‐induced gall monoterpene composition is an augmentation of the specific enantiopolymorphism originally displayed by each individual tree.