Sexual Propagation Enhances Tea Quality Through Rhizosphere Microbiome Assembly and Metabolic Reprogramming in...

Tea quality is largely determined by the accumulation of specialized metabolites in fresh leaves, yet the effects of the propagation method on tea quality and its belowground ecological basis remain insufficiently understood. In this study, sexually propagated (SR) and asexually propagated (AR) tea plants were compared by integrating soil physicochemical analysis, leaf quality and physiological measurements, widely targeted metabolomics, and rhizosphere metagenomic profiling. Compared with AR, SR plants exhibited more favorable rhizosphere nutrient conditions, with soil organic matter, total nitrogen, alkali-hydrolyzable nitrogen, and available phosphorus increasing by 23.1%, 18.2%, 27.8%, and 161.5%, respectively, although available potassium decreased by 24.4%. SR leaves also contained higher dry matter, tea polyphenol, and soluble sugar contents, which increased by 11.5%, 58.8%, and 8.6%, respectively. In addition, superoxide dismutase, peroxidase, and indole-3-acetic acid oxidase activities were 30.4%, 92.0%, and 21.7% higher under SR, whereas hydrogen peroxide content remained unchanged. Metabolomic profiling revealed marked differences in leaf metabolic composition between the two propagation types, with differentially accumulated metabolites mainly enriched in flavonoid biosynthesis, phenolic acid metabolism, caffeine metabolism, carotenoid biosynthesis, plant hormone signaling, and α-linolenic acid metabolism. Rhizosphere metagenomic analysis further showed that SR was characterized by higher relative abundances of Actinomycetota, Pseudomonadota, Planctomycetota, Alphaproteobacteria, and Streptomycetales, together with distinct microbial functional profiles related to glycolysis, the tricarboxylic acid cycle, and pyruvate metabolism. Significant correlations were identified between several SR-enriched microbial taxa and quality-related metabolites, particularly flavonoids and phenolic acids. Overall, under the present field conditions, sexual propagation was more favorable than asexual propagation for tea quality formation, as reflected by improved nitrogen and phosphorus availability, greater accumulation of quality-related metabolites, higher antioxidant enzyme activities, and distinct rhizosphere microbial carbon-metabolic potential. These findings provide an integrated soil-microbiome-metabolome perspective for understanding propagation-related differences in tea quality.