The effect of abiotic and biotic stresses on the production of bioactive compounds in tea (Camellia sinensis (L.) O. Kuntze)

Tea (Camellia sinensis (L.) O. Kuntze) is the most famous, flavored, functional, and therapeutic non-alcoholic beverage, with two-thirds of the world's population drinking it. Tea leaves are demonstrated to contain many bioactive compounds, including polyphenols, amino acids, volatile compounds, and alkaloids, all of which have a good potential of biomedical uses. In plants under stress, including diverse elicitors or signal molecules, accumulation of such metabolites occurs frequently. In adapting plants to the ecosystem and alleviating stress conditions, phytochemicals play a significant role. Ecological factors may be categorized into biotic and abiotic factors which may be artificially induced to activate plant defense responses due to the generation of bioactive compounds. Different biotic and abiotic factors are directly linked to the productivity of tea. Abiotic and biotic factors such as temperature, cold, nutrition, shading, humidity, light intensity, water supply, mechanical, nutrition influence the growth of the plant and the production of the bioactive compounds in tea. Biotic and abiotic factors are versatile tools for the overproduction of valuable metabolites in tea. In this review, an update will be provided on current research focusing on the response of tea to an integration of various stresses. In specific, we will discuss how various stress responses are integrated and how they affect plant growth and physiological characteristics.