Understanding the biosynthesis of irregular monoterpenes for their heterologous production

Plants contained more than 76,000 characterized terpenoids, most of which are derived from two five-carbon isoprenes. Lavenders are utilized industrially to produce perfumes, cosmetics, soaps, antiseptics, disinfectants, and anti-inflammatories. Lavender essential oils are mainly composed of regular monoterpenes such as linalool, linalyl acetate, 1,8-cineole and camphor, while they also have small amounts of irregular monoterpenes including lavandulol and its derivative lavandulyl acetate. Lavandulol was firstly isolated from French lavender oil in 1942. Lavandulol and lavandulyl acetate not only play important role in the cosmetic and perfume industry but also attract extensive attention in pheromone research because they can inhibit the mating behaviors of pests with economic importance. However, the amount of lavandulol (0.1- 3%) and lavandulyl acetate (0.2-3.5%) in most Lavandula plants is quite low. Interestingly, aerial parts of Lavandula lanata during flowering stages can accumulate lavandulol levels up to 39.8% of total essential oil. Given the low content and the possible issues from the chemical synthesis of lavandulol, an alternative environment-friendly, economic and more efficient method is needed to meet the expected increased demand for lavandulol and its derivatives. Metabolic engineering provides another possible approach to producing different kinds of valuable compounds. However, the basis for metabolic engineering for certain compound relies on a complete understanding of its biosynthetic pathway. Although the genes involved in the formation of lavandulyl diphosphate (LPP) and lavandulol acetate have been reported, how lavandulol is biosynthesized from (LPP) remains unclear. Moreover, why Lavandula lanata produces much higher levels of lavandulol than that in Lavandula angustifolia L is currently unknown. Finally, whether the biosynthetic pathway for lavandulol and its derivatives could be reconstituted in other systems is unknown. This proposed project focuses on identifying the molecular and biochemical mechanisms that determining the higher enzyme activity of LPPS in L. lanata through molecular, biochemistry and genetics-related techniques, as well as reconstituting the biosynthetic pathway for lavandulol and its derivatives in Nicotiana benthamiana and Saccharomyces cerevisiae through metabolic engineering. We will compare the ability of LPPS from Lavandula angustifolia and lavandula lanata for the production of lavandulol in planta and in vitro, identify and reveal the key amino acids determining the higher enzyme activity of LPPS, and reconstitute the biosynthetic pathway for lavandulol and its derivatives in Nicotiana benthamiana and Saccharomyces cerevisiae. This study will not only improve our understanding about the biosynthesis of lavandulol, but also provides an alternative approach to produce lavandulol and its derivatives.