Integrated phenotypic, physiological, and transcriptomic analyses reveal light-intensity regulatory mechanisms underlying the multifunctional trait improvement in Dendrobium officinale

Dendrobium officinale Kimura et Migo (D. officinale) is a medicinal herb that is gaining worldwide popularity for its unique edible, medicinal, and ornamental values. However, inconsistent shading in D. officinale cultivation frequently leads to unstable yield and quality. Here, by employing a controlled light-intensity gradient, we systematically investigated light-intensity-responsive traits and their underlying mechanisms in D. officinale, to provide precise management practices that synergistically improve yield and quality. In this experiment, 8-month-old seedlings of D. officinale were exposed to respective light intensities of 2,000, 6,500, 11,000, 15,500, and 20,000 lx for 64 days. The results demonstrated that excessive light enhanced antioxidant enzyme activities and cellulose content, but compromised growth-related traits and edible quality traits, whereas insufficient light produced the opposite effects. Notably, moderate light (11,000 lx) optimally balanced growth and defense, achieving peak biomass and maximal yields of alkaloids, polysaccharides, and flavonoids, together with superior fresh-consumption sensory ratings, thereby enabling synergistic improvements in appearance, yield and quality. Furthermore, D. officinale plants acclimated to moderate light intensity through a coordinated transcriptional network that orchestrated the redistribution of carbon, the remodeling of membrane lipid, and the adjustment of metabolic flux towards photoprotection and bioactive compound synthesis. The findings establish fundamental parameters for light-intensity optimization in D. officinale cultivation and provide insights into photomorphogenic regulation in multifunctional medicinal plants.