Bergamotene
Bergamotenes are a group of isomeric chemical compounds with the molecular formula C15H24. The bergamotenes are found in a variety of plants, particularly in their essential oils.
There are two structural isomers, α-bergamotene and β-bergamotene, which differ only by the location of a double bond. Both of these isomers have stereoisomers, the most common of which are known as the cis and trans-isomers.
α-Bergamotene is found in the oils of carrot, bergamot, lime, citron, cottonseed, and kumquat.
Pheromones
The bergamotenes are pheromones for some insects. For example, β-trans-bergamotene is a pheromone for the wasp Melittobia digitata. Plants can defend themselves against attack by herbivorous insects by producing pheromones such as bergamotenes that attract predators of those herbivores. In a more complex relationship, the tobacco plant Nicotiana attenuata emits α-trans-bergamotene from its flowers at night to attract the tobacco hawk moth as a pollinator; however, during the day the leaves produce α-trans-bergamotene to lure predatory insects to feed on any larvae and eggs that the pollinator may have produced.
Biosynthesis
All the bergamotenes are biosynthesized from farnesyl pyrophosphate via a variety of enzymes including exo-alpha-bergamotene synthase, (+)-endo-beta-bergamotene synthase, (-)-endo-alpha-bergamotene synthase, and others. Bergamotenes, in turn, are intermediates in the biosynthesis of more complex chemical compounds. For example, β-trans-bergamotene is a precursor in the biosynthesis of fumagillin, ovalicin, and related antibiotics.