Abstract

SUMMARY Glucomannans (GMs), which are abundant secondary metabolites in the medicinal orchid Dendrobium officinale , have potential anticancer, antioxidant, and anti-inflammatory activities. Although the biosynthesis of GMs in D. officinale has been extensively studied, the mechanism regulating their biosynthesis remains elusive. This study revealed that jasmonic acid (JA) and R1B9 light signals acted synergistically to promote the accumulation of GMs in D. officinale . Integrated transcriptomic analysis identified DoDof6 , a gene responsive to both JA and R1B9 that was highly expressed in stems. The overexpression of DoDof6 in D. officinale significantly enhanced the accumulation of GMs, mannose, and glucose, and also promoted the conversion of glucose to mannose, while the DoDof6 knockout inhibited this process. Binding of DoDof6 to the AAAAG cis -element directly activated the expression of DoGMP1. In addition, DoDof6 interacted with the central light response regulator DoHY5 , which specifically bound to the G-box element of the DoDof6 promoter, thereby enhancing the transcriptional activation of DoGMP1 . These findings revealed DoDof6 as a key integrator involved in the coordination of JA and light signals to regulate GM biosynthesis in D. officinale. This study offers an understanding of the regulatory mechanism underlying the biosynthesis of GMs, coordinated by the DoDof6 - DoHY5 regulatory module, with the potential of being used to create novel genetic resources in molecular breeding initiatives.