Genome-Wide Identification of the Growth-Regulating Factor (GRF) Gene Family in Three Cymbidium Species and Expression Patterns in C. goeringii

The GRF (Growth-Regulating Factor) gene family has indispensable regulatory functions in the morphological and physiological development of plants. Nonetheless, comprehensive investigations of GRF gene family members and their functional roles in Cymbidium goeringii, Cymbidium ensifolium, and Cymbidium sinense are still lacking. Therefore, the GRF gene family members in three Cymbidium species were systematically identified, and their expression profiles and potential biological functions were comprehensively evaluated in the study. The results provided evidence that eleven, eleven, and nine GRF genes were identified in C. goeringii, C. ensifolium, and C. sinense, respectively. These genes encode proteins considered as 153–584 amino acids and have been postulated to be located in the cell nucleus. The promoter contains cis-acting elements associated with hormone response regulation, tissue-specific expression, modulation of organismal growth and development, and environmental signal response. The analyses of gene architecture and motif composition demonstrated that introns and motifs within each evolutionary branch are highly similar, whereas significant differences exist between evolutionary branches. The results of chromosome localization and collinearity analysis showed that only a pair of segmental duplication genes was identified in C. goeringii. Moreover, transcriptome data and qRT-PCR results indicated that GRF genes are involved in various organs of C. goeringii. In conclusion, these findings may establish a foundation for theoretical inquiry into the future functional analysis of GRF genes in orchids.