Tomato Resistance To Pseudomonas Syringae DC3000 That Mediated By Phenylpropanoid Metabolism

Tomato(Solanum Lycopersicum L.)is one of the vegetables that widely cultivated in the world and mainly grown in greenhouses.Tomato is easy to be infected with more than 200 diseases caused by pathogens such as fungi,bacteria,viruses,and nematodes.At the same time,the closed,weak light and high humidity environment of Greenhouse creates favorable conditions for the spread of the disease.Chemical control of diseases is expensive and often ineffective,and the potential threat of pesticide residues to health and the environment has become increasingly prominent.Therefore,the goal of sustainable agriculture is to study the response and defense mechanism of tomato to diseases and to breed productive disease-resistant varieties.In this study,metabolomics and transcriptomics were executed on tomato inoculation with Pst DC3000,and the mechanism of the phenylpropanoid metabolic pathway and EGCG in disease resistance were discussed.The main conclusions are as follows:1.The lipids such as glyceride and lysophosphate in tomato leaves increased significantly after inoculation,which may promote the metabolism of chloroplast intima.The significant increase in the content of alkaloids such as feruloyl-tyramine and coumarin-tyramine may prevent the movement of pathogenic bacteria.The specific synthesis of triterpenes such as hawthorn acid and 2-hydroxy oleanolic acid may inhibit the growth of bacteria and reducing the toxicity of ROS to cells.2.The gene expression of PTI and ETI resistance pathway in tomato was up-regulated after infection,indicating that PTI and ETI resistance pathway cooperated defense against Pst infection in tomato.The gene expression of photosynthesis was down-regulated after infection,which is the result of promoting ROS accumulation and save cell resources.3.The phenylpropanoid metabolic pathway of tomato was significantly regulated in resisting pathogen infection,the monolignols metabolites increased significantly,and its synthetic lignin played an essential role in defense-induced callose deposition and cell wall thickening.The significant decrease of flavonoid metabolites may be beneficial to the flow of uPstream metabolites to the monolignols metabolic pathway and promote the accumulation of reactive oxygen species in cells.Defense-induced changes in phenylpropanoid metabolites may be regulated by transcription factors such as THM27,MYB12,MYB4.4.The content of EGCG in tomato leaves infected by Pst increased rapidly to 300ng·g-1 FW,and the pretreatment of 100 μM EGCG significantly enhanced the resistance of tomato to Pst.Further study showed that EGCG might be a signal substance in tomato defense,which may promote the transformation of bound salicylic acid into the free state by regulating SABP2 gene,and then initiated the resistance response mediated by salicylic acid.