Integrated phenotypic, physiological, and transcriptomic analyses reveal light-intensity regulatory mechanisms...

Dendrobium officinale Kimura et Migo (D. officinale) is a photosensitive herbaceous plant valued for its unique edible, medicinal, and ornamental properties. However, inconsistent shading during cultivation frequently results in unstable yield and quality. To elucidate the precise regulatory effect of light intensity on D. officinale growth, eight-month-old seedlings were exposed to a gradient of 2,000-20,000 lx for 64 d. The results demonstrated that extreme high light levels enhanced antioxidant enzyme activity and structural carbohydrate accumulation but compromised growth-related traits (e.g., plant height increment and the SPAD value) and edible quality traits (e.g., juice yield, chewability score, and residue score), whereas low light levels exerted the opposite effects. Notably, D. officinale plants grown under the 11,000 lx treatment simultaneously achieved peak biomass yield, maximal yield of bioactive compounds, superior fresh-consumption sensory ratings, and minimized oxidative stress markers, indicating that moderate light intensity synergistically improved multifunctional traits. Transcription profiling further revealed that moderate light mediated light adaptation and trait optimization through coordinated carbon redistribution, membrane lipid remodeling, and metabolic flux repartitioning toward photoprotection and bioactive compound production. Together, these findings not only provided a reference for tailoring light intensity in D. officinale cultivation toward specific edible or medicinal purposes but also established a theoretical framework for the mechanisms by which moderate light intensity coordinately enhanced its biomass yield, edible quality, and medicinal properties.