Not just flavor: Insights into the metabolism of tea plants

Tea, one of the world's most popular beverages, boasts a rich cultural history and distinctive flavor profiles. With advances in genomics and plant metabolism research, significant progress has been made in understanding the biosynthetic pathways and the underlying regulatory mechanisms of tea plants (Camellia sinensis). Tea metabolites play a pivotal role in determining tea flavor, and functional properties, while also being closely tied to the plant's stress resistance, environmental adaptability, and other newly discovered biological functions. In recent years, research has expanded beyond the well-characterized metabolites, such as catechins, l-theanine, and caffeine, to include volatile compounds, hormones, photosynthetic pigments, lignin, and other recently discovered metabolites, shedding new light on the intricate tea plant metabolism. This review highlights the biosynthetic pathways and regulatory mechanisms of key metabolites in tea plants, with a focus on the critical enzyme genes and regulatory factors. Additionally, emerging technologies and methodologies applied in tea plant metabolism research are briefly introduced. By further exploring the biological functions of tea metabolites and their upstream regulatory networks, future studies may offer theoretical insights and technological support for tea plant cultivation, tea quality improvement, and the sustainable development of the tea industry.