Involved in the biosynthesis of homoterpenes, attractants of herbivores parasitoids and predators (e.g. predatory mites and parasitoid wasps). Catalyzes the conversion of the C20 (E,E)-geranyllinalool to C16-homoterpene 4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT) of the C15 (E)-nerolidol to C11-homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT); these volatile compounds are produced upon insect herbivore attack and emitted from flowers and vegetative tissues during herbivore feeding. Required during resistance responses to the fungus Alternaria brassicae. Prevents oviposition of the phloem-feeding insect cabbage whitefly (Aleyrodes proletella)