Metabolic Diversity And Biological Function Of Diterpenoids In Artemisia Annua L.

More than 12,000 plant diterpenoids in nature have diverse physiological and biological functions.Among them,gibberellins(GAs)are a class of hormones that exist in all higher plants and are widely involved in the growth and development process.The study found that GAs significantly promoted the development of non-secretory glandular hairs in Arabidopsis.However,its effect on secreted glandular hairs(glandular trichomes,GSTs)has not been revealed.Artemisinin(AN)is used to treat malaria.It is specifically synthesized by special ten-cell GSTs of Artemisia annua L.,and its content is closely related to the development of glandular hairs.Therefore,elucidating the relationship between GAs and the development of Artemisia annua GSTs is of great significance for increasing the number of GSTs and AN content.On the other hand,plant diterpenes have extensive anti-stress activity.The study found that the diterpene antitoxins of monocotyledonous maize and rice,and the diterpene resin acids of gymnosperm pine play an important role in stress resistance,and actively guarantee the accumulation of biomass in adverse environments.With the further exploration of the clinical value of Artemisia annua,its market demand continues to rise,and the increasingly complex living environment poses a huge challenge to the growth of Artemisia annua.Therefore,to clarify the potential anti-stress activity of Artemisia annua diterpenes is of great significance to overcome the challenges of environmental stress.In this project,10 diterpene synthases(diTPSs)were screened,and their catalytic activity was verified based on the E.coli synthetic biology platform to clarify the biosynthetic pathways of Artemisia annua diterpenes.Through RT-qPCR spatiotemporal expression analysis,it was found that AaTPSd,AaTPSa1 and AaTPS3 have similar expression characteristics,and were induced by MeJA.It was speculated that they may participate in the biosynthesis of anti-stress active substances.In this project,through protein-protein interaction(PPI)experiments,it was found that both AaTPSd and AaTPSc could interact with AaTPSa1 to form a complex in the plastid.This indicated that the formation of dimers depends on protein structure,notbiochemical activity.Based on this,the construction of AaTPSd and AaTPSa1 fusion expression,single gene expression and double gene expression transgenic Artemisia annua,through the analysis of glandular hair growth status,artemisinin content and stress resistance,showed that AaTPSd regulates the number and development of glandular hairs through GAs Density,which in turn affects artemisinin biosynthesis.At the same time,the stress resistance of AaTPSd and/or AaTPSa1 overexpressing plants was significantly improved,which fully demonstrated that Artemisia annua diterpene had the biological function of resisting microbial stress.In summary,this study 1)for the first time resolved the biosynthesis of 8,13-CPP in the dicotyledon Artemisia annua(only found in monocotyledonous crops);2)for the first time elucidated the diterpene biosynthetic pathway in A.annua;3)Systematically verified that class II and class I diterpene synthases could form dimeric complexes in plastids;4)clarified that diterpene metabolism had important biological significance for the development and resistance of Artemisia annua.