Volatile Terpene Synthesis And Its Physiological Function In Response To Drought Stress In Tea(Camellia Sinensis)

Tea plant(Camellia sinensis(L.)O.Kuntze)as one of the most important economic crops always confronted with kinds of biotic and abiotic stress throughout its life cycle,especially drought stress which constrained growth,yield and quality of the tea plant.There are plenty of studies proved that plants can communicate with each other via stress-induced volatile organic compounds(VOCs),however,untill today,the VOCs-mediated plant-plant communication from the above ground tissues under drought stress are rarely reported.In this study,we carry out the volatile exchange experiment,physiological measurements,determination the amount of volatiles released from tea seedlings under drought stress,exogenous aroma exposure,transcriptome and metabolic analysis,analyze the changes and physiological functions of volatile cues,and transcriptome-metabolome correlation analysis were applied to mine a new terpene synthase gene TPS2.The function of TPS2 was verified in vitro(prokaryotic expression)and in vivo(transient silencing in tea shoots).The main findings are as follows:1.Drought-stressed tea plants reduce the drought resistance of their neighbours,mainly manifested as more severe wilting degree,lower water content and osmotic potential of leaves,higher MDA content and ROS accumulation,and lower activity of antioxidant enzyme.2.The release of volatiles changed,mainly nerolidol,α-/β-farnesene andβ-bisabolene terpenes decreased,green leaf volatiles,Me SA,benzyl alcohol and phenethyl alcohol increased significantly.3.Aroma exposure experiment showed that low content of Me SA can inhibit synthesis of ABA and stomatal closure,thus reducing the drought resistance of adjacent tea seedlings.While nerolidol and β-farnesene can improve the antioxidant capacity of tea seedlings,however,the amount of release sharply reduced,which may weakened the antioxidant ability of adjacent tea seedlings.4.A new terpene synthase,TPS2,was found through transcriptome-metabolome correlation analysis of five different tissue of tea,which can catalyze the synthesis of α-/β-farnesene and β-ocimene in vitro,α-farnesene and β-ocimene in tea plant.