# Effects of Light Quality on Anthocyanin Biosynthesis and Related Gene Expression in Camellia sinensis ‘Ziyan’

## TL;DR

This study shows that blue and red light increase anthocyanin levels in purple-leaf tea, with blue light being most effective, offering insights for better cultivation practices.

## Contribution

The study reveals the specific effects of red and blue light on anthocyanin biosynthesis and gene expression in Camellia sinensis ‘Ziyan’.

## Key findings

- Blue light increased total anthocyanin content by 29.64% compared to white light.
- Blue light upregulated key anthocyanin structural genes while downregulating their transcription factors.
- Delphinidin, cyanidin, and pelargonidin levels increased significantly under blue and red light.

## Abstract

The purple-leaf tea cultivar ‘Ziyan’ is characterized by its high anthocyanin levels, which confer unique visual traits and health benefits. However, the effects of light quality on anthocyanin production remain poorly understood. This study explored the effects of red and blue light on anthocyanin biosynthesis in ‘Ziyan’, with white light as the control, using transcriptomic analysis, enzyme assays, and anthocyanin content measurements. The results showed that anthocyanin content increased under blue and red light, with blue light being the most effective, as the total anthocyanin content reached 81.79 mg/100 g FW, a 29.64% increase compared with white light. Delphinidin, cyanidin, and pelargonidin increased by 27.52%, 42.58%, and 102.72%, respectively. Transcriptome analysis showed red and blue light influenced photoreceptors and light signaling components, with decreased COP1 and increased SPA1 expression. Blue light upregulated key anthocyanin structural genes despite downregulating their transcription factors; it enhanced CHS, F3′H, F3′5′H, and ANS activities but decreased LAR and ANR activities, similar to the effect of red light. This research showed that the underlying mechanism may be achieved by coordinating light perception, gene expression, and enzyme activity. This study provides a theoretical basis for optimizing the light quality in purple tea plant cultivation.