Genome-Wide Identification of TCP Gene Family in Dendrobium and Their Expression Patterns in Dendrobium chrysotoxum .

The TCP gene family are plant-specific transcription factors that play important roles in plant growth and development. Dendrobium chrysotoxum , D. nobile , and D. huoshanense are orchids with a high ornamental value, but few studies have investigated the specific functions of TCP s in Dendrobium flower development. In this study, we used these three Dendrobium species to analyze TCP s, examining their physicochemical properties, phylogenetic relationships, gene structures, and expression profiles. A total of 50 TCP s were identified across three Dendrobium species; they were divided into two clades-Class-I (PCF subfamily) and Class-II (CIN and CYC/TB1 subfamilies)-based on their phylogenetic relationships. Our sequence logo analysis showed that almost all Dendrobium TCP s contain a conserved TCP domain, as well as the existence of fewer exons, and the cis -regulatory elements of the TCP s were mostly related to light response. In addition, our transcriptomic data and qRT-PCR results showed that DchTCP2 and DchTCP13 had a significant impact on lateral organs. Moreover, changes in the expression level of DchTCP4 suggested its important role in the phenotypic variation of floral organs. Therefore, this study provides a significant reference for the further exploration of TCP gene functions in the regulation of different floral organs in Dendrobium orchids.