Elevated Carbon Dioxide-Induced Perturbations in Metabolism of Tea Plants

Abstract

Rising CO2 on the earth’s surface is the single most influential driving force for climate change. A CO2-enriched environment impacts leaf chemistry and metabolism, leading to remarkable changes in plant productivity. While effect of elevated CO2 on the yield of economic crops has been well addressed, its impact on important beverage crops such as tea (Camellia sinensis L.) has received less attention. In tea plants, elevated CO2 increases photosynthesis and the production of photoassimilates, whereas increased photosynthesis necessitates increased respiration to provide more energy to drive photosynthesis. Furthermore, elevated CO2 increases total carbon concentration and decreases total nitrogen concentration, resulting in an increased ratio of carbon to nitrogen in tea leaves. Despite the discrepancies in research reports, elevated CO2 improves tea quality by causing enhancements in the concentrations of tea polyphenol, free amino acid, including theanine and a reduction in that of caffeine. A proper balance between photosynthesis and respiration under elevated CO2 increases net productivity in tea; however, tea plant defense response to necrotrophic pathogens is attenuated in a CO2-enriched environment. In this chapter, we aim to review and summarize available literature on the changes in plant physiological processes, primary and secondary metabolite synthesis, nutraceutical properties, overall tea quality, tea yield, and plant defense in response to elevated CO2.