Metabolic Profiling of Cultivated Bush Tea (Athrixia phylicoides DC.) in Response to Different Pruning Types

Abstract

Bush tea (Athrixia phylicoides DC.) is a popular medicinal South African indigenous plant and it has been used for many decades as a health beverage and medicine. The objective of the study was to profile metabolites for assessment of quality of bush tea (A. phylicoides DC.) subjected to different pruning levels. Treatments consisted of untreated control, top-branch pruning, middle pruning, and basal pruning arranged in a randomized complete block design (RCBD) using 10 single trees as replications. The liquid chromatography quadrupole time-of-flight mass spectrometry (LC–QTOF–MS) was carried out to annotate the bush tea metabolites present in bush tea. Orthogonal partial least square-discriminatory analysis (OPLS-DA) from 1H nuclear magnetic resonance (NMR) revealed a separation between the basal, middle, top pruning, and the unpruned bush tea plants. The pruned (top) and unpruned tea plants, exhibited higher levels of metabolites than the basal and middle pruned. Pruning bush tea showed a significant effect on accumulation of secondary metabolites and thus could enhance bush tea quality. The study successfully annotated 28 metabolites (compounds), which elucidated canonical differences in pruning treatment of bush tea, as validated through multivariate analysis. Top pruning (apically pruned) resulted in improved metabolite accumulation than other treatment and can be recommended in bush tea cultivation. Future studies to enhance vegetative enhancement after pruning will be evaluated.