Dendrobium catenatum is an important traditional Chinese medicine and naturally grows on tree trunks and cliffs, where it can encounter diverse environmental stimuli. MYB transcription factors are widely involved in response to abiotic stresses. However, the MYB gene family has not yet been systematically cataloged in D. catenatum. In this study, a total of 133 MYB proteins were identified in D. catenatum, including 32 MYB-related, 99 R2R3-MYB, 1 3R-MYB, and 1 4R-MYB proteins. Phylogenetic relationships, conserved motifs, gene structures, and expression profiles in response to abiotic stresses were then analyzed. Phylogenetic analysis revealed MYB proteins in D. catenatum could be divided into 14 subgroups, which was supported by the conserved motif compositions and gene structures. Differential DcMYB gene expression and specific responses were analyzed under drought, heat, cold, and salt stresses using RNA-seq and validated by qRT-PCR. Forty-two MYB genes were differentially screened following exposure to abiotic stresses. Five, 12, 11, and 14 genes were specifically expressed in response to drought, heat, cold, and salt stress, respectively. This study identified candidate MYB genes with possible roles in abiotic tolerance and established a theoretical foundation for molecular breeding of D. catenatum.

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Dendrobium catenatum is a valuable Chinese herbal medicine that naturally grows on cliffs and tree trunks and is often threatened by adverse environmental conditions. The bZIP transcription factor is known to play a critical role in the response of plant to stress. However, the functions of the bZIP gene family in D. catenatum are poorly understood. In this study, 62 bZIP genes were identified from D. catenatum, which encoded proteins with an amino acid number of 130~692, a molecular weight of 15.24 to 74.94 kDa, and an isoelectric point of 5.13 to 11.58. The bZIP family can be divided into 10 subgroups by evolutionary tree analysis, and the conserved motifs of each protein subgroup were similar. The exon number of bZIP genes ranged from 1 to 12 as shown by gene structure analysis. DcbZIP promoter prediction analysis identified 21 cis-acting elements. The expression of DcbZIP genes under drought treatment was analyzed using the public RNA-seq data, and 33 upregulated genes were further screened. A co-expression network analysis revealed that 17 core genes were closely correlated with other genes and their expression was measured using RT-qPCR. The results showed that DcbZIP6, DcbZIP34, DcbZIP42 and DcbZIP47 are the main contributors to drought tolerance in D. catenatum. In summary, we identified candidate bZIP genes in D. catenatum with a apotential contribution to drought stress response, and this study lays the foundation for exploring the functions of bZIP and provides a theoretical basis for improving the drought tolerance of D. catenatum.