The sustainable development of valuable and endangered Chinese herbal resources is a key scientific issue that needs to be addressed by the Chinese medicine industry. The wood of Aquilaria sinensis (Lourl.) Gilg is a resinous wood that is slowly formed after the plant Aquilaria sinensis (Lourl.) has been attacked, and is a valuable herb and spice for its ability to move qi and relieve pain, warm vomiting and calm asthma. Because of its unique fragrance, it ranks as one of the top four famous incenses of "sunken sandalwood and dragon musk", and the price per gram of high quality incense can reach thousands of dollars, enjoying the reputation of "diamond in the wood". White incense is the only source of incense herbs in China, and is a rare and valuable medicinal plant unique to China. Due to its low natural reproduction rate and predatory logging, the forest resources and ecological environment have been severely damaged and the wild resources are on the verge of depletion, and it has been listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and is a Grade II protected plant in China. Under natural conditions, incense is mainly produced by insects, fungal infections, external injuries and other factors that cause defensive reactions, and its incense production is slow and very low. To clarify the formation mechanism of incense and to intervene in the process of incense formation is the core of breaking through the current limitations of artificial incense formation technology and solving the problem of incense resources once and for all.
The formation of incense is essentially the slow synthesis and accumulation of defensive secondary metabolites, phenylethylchromones and sesquiterpenes, in the body. The phenylethyl chromones are unique to incense and are the main substances responsible for its efficacy and unique aroma. In collaboration with scholars from the University of Toyama and the University of Tokyo, our team has deciphered the biosynthetic mechanism of phenylethylchromone and constructed a biosynthetic system for the rapid synthesis of structurally diverse phenylethylchromone using suspension cells of Melaleuca alternifolia. The in vivo biological functions of PECPS were demonstrated by transient expression of PECPS in C. benthamiana and knockdown of PECPS in C. alba healing tissues. The crystal structures of PECPS and its four key mutant proteins were prepared and resolved, and the unique catalytic mechanism of PECPS was elucidated. The results of the research breakthrough the key scientific issues of using synthetic biology to synthesize phenylethylchromone components of incense and to precisely regulate the fragrance formation of white mullein.
