Overexpression of geranyl diphosphate synthase small subunit 1 (LcGPPS.SSU1) enhances the monoterpene content and biomass

•LcGPPS.SSU1 had the highest expression in fruit which was the factory of essential oil.•The promoter of LcGPPS.SSU1 could drive trichome-specific expression in tobacco.•Overexpression of LcGPPS.SSU1 enhanced the monoterpene production in L. cubeba.•LcGPPS.SSU1 overexpressing tobacco lines showed the increased of monoterpene production and biomass.•Overexpression of LcGPPS.SSU1 promoted the metabolic flux of MEP pathway by feedback regulating mechanism.