Different performance of tea plants to shade based on key metabolites and transcriptome profiles: case study of cultivars Longjing 43 and Yabukita

Shading is widely used in tea cultivation to improve quality by modulating various metabolic pathways in tea plants. However, the differential sensitivity of specific metabolites and the cultivar-dependent responses to shading are not yet fully understood. This study examined the impact of shading on the chemical composition and transcriptional profiles of cv. Longjing 43 and cv. Yabukita. Among the main quality-related compounds, flavonol glycosides were highly responsive to shading, while catechins displayed distinct cultivar-specific responses. KEGG enrichment analysis revealed that flavonoid biosynthesis was the key secondary metabolic difference between cv. Longjing and cv. Yabukita plants under the sunlight, and shading regulated flavonoid biosynthetic pathways in both cultivars. The genes such as ANTHOCYANIDIN REDUCTASE (CsANR) and ANTHOCYANIDIN SYNTHASE (CsANS) were less sensitive to shade in cv. Longjing 43 than cv. Yabukita, leading to relatively higher levels of epi-type catechins in the shade-treated cv. Longjing 43 sample. Additionally, the UVR8-mediated light signaling pathway demonstrated cultivar-specific expression patterns, although the functional roles of key signaling proteins were conserved across both cultivars. The insights into the chemical and molecular responses of tea plants to shading deepen our understanding of the mechanisms driving the cultivar-dependent behaviors of flavonoids, which offers valuable applications for maintaining consistent matcha quality and informing breeding programs of matcha.