The trihelix family of transcription factors: Functional and evolutionary analysis in Moso bamboo (Phyllostachys edulis)

Abstract

Background: Trihelix transcription factors (TTFs) are photoresponsive proteins that have a representative three-helix structure (helix-loop-helix-loop-helix). Members of this gene family have been reported to play roles in many plant processes. Results: In this study, we performed a functional and evolutionary analysis of the TTFs in Moso bamboo (Phyllostachys edulis). A total of 35 genes were identified and grouped into five subfamilies (GT-1, GT-γ, GT-2, SIP1 and SH4) according to their structural properties. Gene structure analysis showed that most genes in the PeTTF family had fewer introns. A unique motif (Motif 16) to the GT-γ subfamily was identified by conserved motif analysis. Promoter analysis revealed various cis-acting elements related to plant growth and development, abiotic and biotic stresses, and phytohormone responses. Data for the 35 Moso bamboo TTF genes were used to generate heat maps, which indicated that these genes were expressed in different tissues or developmental stages. Most of the TTF genes identified here had high expression in leaves and panicles according to the expression profile analysis. The expression levels of the TTF members in young leaves were studied using quantitative real-time PCR to determine their tissue specificity and stress-related expression patterns to help functionally characterize individual members. Conclusions: The results indicated that members of the TTF gene family may be involved in plant responses to stress conditions. Additionally, PeTTF29 was shown to be located in the nucleus by subcellular localization analysis and to have transcriptional activity in a transcriptional activity assay. Our research provides a comprehensive summary of the PeTTF gene family, including functional and evolutionary perspectives, and provides a basis for functionally characterizing these genes.