Table 1_Mechanisms of acclimation regulation and stress response to UV-B in Dendrobium nobile Lindl..doc

Transcriptomic analysis revealed that at 20 μW cm⁻², transcription factors including DnHY5, DnPCL1, DnMYBx1, DnBIM2, DnSCL9-l, DnMYBS3, DnBHLH66-l, DnWRKY2, DnPCF2, DnC3H2, and DnC3H14 may be involved in photomorphogenic acclimation, with key biosynthetic genes (DnC4H, DnCAD, DnCHI, DnCHS, DnPOD12, DnMVK, DnMVD) upregulated. In contrast, 80 μW cm-2 UV-B induced evident stress damage and activated stress-responsive genes (DnXTH, DnCYP77A6, DnCER1, DnCry-DASH, DnPHR, DnH64PHR), while suppressing several chemical biosynthesis-related genes.</p>Discussion<p>These findings demonstrate that low-intensity UV-B (20 μW cm-2) promotes major chemical classes accumulation through photomorphogenic acclimation without significant stress damage, whereas high-intensity UV-B (80 μW cm-2) induces non-specific stress responses.

This study provides a mechanistic framework for strategic UV-B application to improve medicinal plant quality and suggests optimized cultivation protocols for high-quality D. nobile production.</p>