Research Progress on Stay-green Gene in Tea Plants

The stay-green genes (SGRs) are crucial in regulating chlorophyll degradation and leaf senescence of plants through chloroplast homeostasis, leaf color transition, and stress adaptation. In recent years, with the advancement of functional genomics in tea plants, the potential roles of CsSGR family have attracted increasing attention. Studies have shown that they may affect leaf color formation and senescence in tea plants by participating in chlorophyll degradation and regulating the stability of chlorophyll–protein complexes. Their expression is regulated by multiple signals, including light, temperature, phytohormones, and pathogens, and functions differentiated among members. Meanwhile, CsSGR-mediated leaf color changes and chloroplast metabolic remodeling may further affect the accumulation of quality-related compounds, such as amino acids, tea polyphenols, and caffeine, and closely associated with processing suitability of a specific tea cultivar as well. This article summarizes the classification, functions, and chlorophyll degradation mechanism of SGRs and the expressions, regulatory characteristics, and potential roles in stress adaptation and quality formation of CsSGRs in aiding the functional analysis of CsSGRs as well as breeding for high-quality, stress-resistant varieties.