Metabolomics And Transcriptomes Studies On Exogenous Tea Polyphenols On The Drought Resistance Of Tea Plant

Tea is one of the most important beverage plants in the world,with an annual water demand of more than 1040 mm.Drought is the main abiotic stress that affects the growth of tea plants.Water shortage causes a sharp increase of reactive oxygen species（ROS）in tea plants,which will lead to the oxidation of cell membranes,nucleic acids and lipids,and eventually cause plant death,resulting in significant economic losses to the tea industry.Tea polyphenol is an important secondary metabolite in tea plant,which is an indispensable secondary antioxidant under stress and an important bioactive component affects tea quality.In this study,Baojing huangjincha 1,was used as the research object,and the combined analysis of metabolomics and transcriptomics was used to explore how exogenous tea polyphenols affect the drought resistance of tea plant.The main research results are as follows:（1）In this study,it was found that exogenous tea polyphenols irrigated with100 mg·L^-1 could change the resistance of tea plants.Exogenous tea polyphenols could promote stomatal closure of tea leaves under drought stress,reduce the loss of water in soil and leaves,and improve the drought tolerance of Baojing huangjincha 1.（2）Transcriptome analysis showed that the differentially expressed genes in tea roots under drought stress induced by exogenous tea polyphenols were mainly concentrated in GO items related to antioxidation,such as hydrogen peroxide decomposition process（GO:0042744）,peroxidase activity（GO:0004601）,oxidoreductase activity,peroxide as receptor（GO:0016684）and so on.Metabonomic analysis showed that the differential metabolites in roots were mainly concentrated in antioxidants such as alkaloids and flavonoids.The malondialdehyde（MDA）content in tea leaves and roots caused by drought also decreased significantly under the treatment of exogenous tea polyphenols.These indicate that exogenous tea polyphenols may improve the antioxidant capacity of tea roots（4）Combined analysis of transcriptomes and metabolomics showed that exogenous tea polyphenols induced the accumulation of jasmonic acid-isoleucine （JA-ILE）in tea roots under drought stress,jasmonic acid-isoleucine synthase genes（TEA028623）,jasmonic acid ZIM domain protein（JAMs）（novel.22237,TEA001821）and transcription factors MYC2（TEA014288,TEA005840）related to jasmonic acid signal pathway were significantly up-regulated,induce jasmonic acid signal transduction and regulate gene expression（5）Exogenous tea polyphenols changed the metabolic flow of flavonoids in tea roots under drought stress,the accumulation of epicatechin glycosides was the most significant,and the contents of theaflavins（TF1）,epigallocatechin gallate（ECG）,epigallocatechin gallate（EGCG）,gallic catechin gallate（GCG）and catechin gallate（CG）increased significantly.Epicatechin（EC）and four lipid catechins may be important biomarkers.The significant accumulation of glycosides caused by exogenous tea polyphenols may also play an important role in the drought resistance of tea plants...