Objective Structure, function, and expression of the transcription factor in the eukaryotes crucial in plant growth, development, and stress response of the basic helix loop helix (bHLH) proteins in Dendrobium officinale were analyzed.

Methods DobHLH63 was cloned using RT-PCR and bioinformatically analyzed. Spatiotemporal expressions of the gene under various conditions were determined by qRT-PCR.

Results The coding region of DobHLH63 was 966 bp long and encoded 321 amino acids. The gene was possibly located in the nucleus and cytoplasm with 29 phosphorylation sites but had no apparent signal peptide or transmembrane domain. It closely related to and shared functions with PzbHLH63 and paralog DobHLH74 of Aponogeton madagascariensis. The WD40 transcription factor appeared to be an important interacting protein. The higher expression in the leaves than in the stems responded to abiotic stress and hormone treatments, especially alkaline salt stress and salicylic acid treatment.

Conclusion DobHLH63 regulated the response of D. officinale to abiotic stress and hormones by binding to the transcription factors, such as WD40.