âAnji Baichaâ (Camellia sinensis) is a lowâtemperatureâsensitive tea variety. During the development of young shoots, the leaves of âAnji Baichaâ exhibit periodic albinism. The quality of âAnji Baichaâ is closely related to the color of the fresh leaves, with whiter leaves affording a higher amino acid content and superior sensory quality after processing. However, the metabolic mechanism of its quality formation is still unclear. In this study, we analyzed the metabolomic changes of young shoots of âAnji Baichaâ and screened for metabolic markers that may be involved in the periodic albinism. Positiveâ and negativeâmode UPLCâQTOFâMS was applied to the metabolomic analysis of young leaves of âAnji Baichaâ during three developmental stages (i.e., the preâalbescent, albescent, and regreening stages). The results revealed significant differences in the metabolic profiles of the young leaves at the three stages. The differential metabolites were mainly related to the pathways of flavonoid, phenylpropanoid, and amino acid biosynthesis. The concentrations of several amino acids (primarily lâtheanine, lâglutamate, N2âacetylâlâornithine, lâaspartic acid, dâproline, lâglutamine, lâleucine, and pyroglutamic acid) and 12âOPDA were significantly higher in the albescent stage. In contrast, during the albescent stages, the concentrations of several carbohydrates (dâfructose, ÎČâdâgalactopyranose, 3âOâfucopyranosylâ2âacetamidoâ2âdeoxyglucopyranose, galactoseâÎČâ1, 4âxylose acetylâmaltose, and 2âfucosyllactose) were significantly lower. Moreover, catechins (mainly epigallocatechin and catechin derivatives), dimeric catechins (primarily proanthocyanidins), and flavonol and flavonol/flavone glycosides (mainly kaempferol, myricetin, quercetin, cyanidin, and delphinidin glycosides) were detected at the highest levels in the regreening or preâalbescent stages. The obtained results enhance the current understanding of the metabolic mechanisms of periodic albinism and quality development formation in âAnji Baichaâ.
Practical Application
The obtained results not only provide information regarding differential metabolites but also advance the understanding of the mechanism of periodic albinism in âAnji Baichaâ at the metabolite level and open up new possibilities for the genetic improvement of tea cultivars.