The transcription factor DhDOF5 regulates mannose biosynthesis in Dendrobium huoshanense under low-temperature and...

Transcription factor proteins are important biological macromolecules that regulate plant metabolic pathways and stress responses. In Dendrobium huoshanense C. Z. Tang et S. J. Cheng, mannose biosynthesis is closely related to polysaccharide accumulation, however, the protein-level regulators involved in this process remain poorly understood. In this study, a Dof family transcription factor protein, DhDOF5, was identified as a candidate regulator of DhPMM, a key enzyme gene involved in mannose biosynthesis. Bioinformatic and structural analyses showed that DhDOF5 contains a highly conserved Dof DNA-binding domain, supporting its potential function as a transcription factor protein. Yeast one-hybrid and electrophoretic mobility shift assays further confirmed that DhDOF5 directly binds to the DhPMM promoter. Functional analysis in transgenic Arabidopsis thaliana showed that DhDof5 enhanced tolerance to low-temperature and water-deficit stress and promoted polysaccharide accumulation. These findings provide direct evidence that DhDOF5 functions as a DNA-binding transcription factor protein involved in the regulation of mannose biosynthesis under abiotic stress. This study highlights a functional biological macromolecule linking transcriptional regulation with polysaccharide metabolism in D. huoshanense. SIGNIFICANCE STATEMENT: This study characterizes DhDOF5 as a transcription factor protein macromolecule that binds to the DhPMM promoter and contributes to stress-associated polysaccharide accumulation in Dendrobium huoshanense.