EngineeringNicotiana tabacumfor thede novobiosynthesis ofDMNTto regulate orientation behavior of the parasitoid waspsMicroplitis mediator

BACKGROUND (E)-4,8-dimethylnona-1,3,7-triene (DMNT), one of the homoterpenes, is thought to contribute to plant indirect defense against insect herbivores. DMNT-enriched plants have great application potential to regulate insect behavior in the 'push & pull' strategy of pest management. However,de novobiosynthesis of DMNT in plants without a homoterpene metabolic pathway in their wild type is still not achieved, and the role of DMNT played in these plants and their interacted insects remains unclear. RESULTS Cytochrome P450s and terpene synthases involved in homoterpenes biosynthesis in cotton plants were employed to generate DMNT-releasing tobacco plants. SingleGhTPS14 transgenicNicotiana tabacumonly emitted (E)-nerolidol, the precursor of DMNT. Transgenic tobaccos expressing singleGhCYP82Ls were unable to produce DMNT or TMTT, while DMNT was detected when exogenous (E)-nerolidol was added. Compared to wild-type plants, only co-expression ofGhCYP82Ls andGhTPS14 in transgenic tobaccos triggered the constitutive release of single-component DMNT. Furthermore, DMNT-emitting transgenic tobacco plants, whether infested withHelicoverpa armigeralarvae or not, significantly incited orientation behavior of parasitoid waspsMicroplitis mediator. CONCLUSION Wild typeN. tabacumplants have no DMNT metabolic pathway. DMNT could bede novobiosynthesized via co-expression ofGhCYP82Ls andGhTPS14. What is more, the parasitoid waspM. mediatorcould be recruited by DMNT-releasing transgenic tobaccos, especially byH. armigera-infested transgenic tobaccos, suggesting the potential roles of engineeredN. tabacumin regulating the behavioral preference ofM. mediator.

Automated summary

Wild type N. tabacum plants do not have a DMNT metabolic pathway. DMNT can be de novo biosynthesized through the co-expression of GhCYP82Ls and GhTPS14. Furthermore, DMNT-releasing transgenic tobacco plants can recruit parasitoid wasps, especially when infested with H. armigera, suggesting potential roles in regulating the behavioral preference of parasitoid wasps.