Growth and Transcriptional Regulation of Camellia sinensis Planted in Understory Mode Revealed by Transcriptomic, Metagenomic, and Machine-Vision Analyses

Camellia sinensis is a significant economic and medical plant. The plant is short and thrives in shaded environments, making it suitable for cultivation under forest canopies. However, the mechanisms governing the growth of C. sinensis in understory conditions need to be fully understood. The study aims to delve into the growth regulatory mechanisms of C. sinensis in understory mode and the impact of the environment on its growth efficiency and bioactive compound synthesis. Through physiological measurements, transcriptomics, metagenomics, and machine vision analysis, a systematic investigation of C. sinensis characteristics in different environments was conducted. Transcriptome data comparisons unveiled key gene expression changes, and the role of these genes in biosynthetic pathways was validated using quantitative Polymerase Chain Reaction (qPCR). Concurrently, metagenomic analysis of soil microbial communities revealed the environmental effects on microbial diversity. C. sinensis in understory mode exhibited higher stomatal density and smaller pore sizes under low light and humidity conditions; phenolic and flavonoid compounds were identified as the main regulatory pathways, with enhanced expression of key genes such as Dihydroflavonol-4-Reductase ( DFR ), Anthocyanidin Reductase ( ANR ), and Leucoanthocyanidin Reductase ( LAR ), which promoted the synthesis of tea polyphenols and lignin, the abundance of Acidobacteria might be related to the growth of C. sinensis in understory mode. Furthermore, machine vision models indicated that C. sinensis displayed higher growth efficiency in the understory mode environment. This research discovered the characteristics of C. sinensis in understory mode and elucidated its growth efficiency in understory mode by modulating phenolic and flavonoid metabolism key genes and promoting the accumulation of secondary metabolites. Differences in soil microbial communities could also affect vegetation coverage and other aspects. These findings provide a scientific basis for optimizing understory mode cultivation and highlight the crucial importance of multidisciplinary approaches in understanding plant adaptability.