The Changes in Metabolites, Quality Components, and Antioxidant Activity of Tea (Camellia sinensis) Infected with Exobasidium vexans by Applying UPLC-MS/MS-Based Widely Targeted Metabolome and Biochemical Analysis

Abstract

Blister blight infected with Exobasidium vexans is one of the most destructive foliar diseases that seriously affects the quality and yield of tea. This research was to investigate the metabolite changes of healthy and infected leaves on tea cultivar “Fuding Dabaicha”, as well as further explore the potential antimicrobial substances against E. vexans infection. In total, 1166 compounds were identified in the whole stage of infection, among which 73 different common compounds were significantly accumulated involved in the important antimicrobial substances of flavonoids and phenolic acids, including kaempferol (3,5,7,4'-tetrahydroxyflavone), kaempferol-3-O-sophoroside-7-O-glucoside, phloretin, 2,4,6-trihydroxybenzoic acid, galloylprocyanidin B4, and procyanidin C1 3'-O-gallate, which indicated that these metabolites might positively dominate the resistance to E. vexans. Furthermore, the relevant biological pathways, such as “Flavone and flavonol biosynthesis”, “Flavo-noid biosynthesis”, and “Phenylpropane pathway”, were more closely related to the resistance against E. vexans. Additionally, total flavonoids, phenolics, alkaloids and terpenoids contributing to antimicrobial and antioxidant capacity altered significantly in four different infection periods, especially the Leaf_S2 stage (the second stage of infection) in which the concentration accumulated the most. The leaves affected by E. vexans infection at the second stage had the relatively highest antioxidant activity. Accordingly, this study provided a theoretical support and comprehensive insights into the effects on the metabolite changes, tea quality components and antioxidant activity of blister blight caused by E. vexans.