Genome-Wide Identification of Trihelix Genes in Moso Bamboo (Phyllostachys edulis) and Their Expression in Response to Abiotic Stress

Trihelix proteins, which are a plant-specific family of transcription factors (TFs), play important roles in plant growth and development, as well as in the plant response to biotic and abiotic stressors. The DNA-binding domain of trihelix proteins is a tryptophan-enriched tandem repeat, forming a helix–loop–helix–loop–helix structure. Here, we identified and characterized 24 full-length trihelix genes from Phyllostachys edulis and classified these genes into 6 previously described subfamilies. Within a given subfamily, the trihelix genes shared similar conserved motifs and structures. Most of the promoters of the trihelix genes in P. edulis contained stress-related cis-elements. Our tissue-specific and gene expression analysis using quantitative real-time PCR indicated that the trihelix genes were expressed primarily in the stems, followed by leaves and roots, and were regulated by cold, drought, and salt stresses. This study delivers novel insights into the phylogenetic relationships and functions of the trihelix TFs of P. edulis. Our results provide a framework for further functional studies investigating the diverse roles of trihelix genes in other bamboo species.