Identification and Characterization of the AREB/ABF Gene Family in Three Orchid Species and Functional Analysis of DcaABI5 in Arabidopsis .

AREB / ABF (ABA response element binding) proteins in plants are essential for stress responses, while our understanding of AREB / ABFs from orchid species, important traditional medicinal and ornamental plants, is limited. Here, twelve AREB / ABF genes were identified within three orchids' complete genomes and classified into three groups through phylogenetic analysis, which was further supported with a combined analysis of their conserved motifs and gene structures. The cis -element analysis revealed that hormone response elements as well as light and stress response elements were widely rich in the AREB/ABF s. A prediction analysis of the orchid ABRE / ABF -mediated regulatory network was further constructed through cis -regulatory element (CRE) analysis of their promoter regions. And it revealed that several dominant transcriptional factor (TF) gene families were abundant as potential regulators of these orchid AREB/ABF s. Expression profile analysis using public transcriptomic data suggested that most AREB/ABF genes have distinct tissue-specific expression patterns in orchid plants. Additionally, DcaABI5 as a homolog of ABA INSENSITIVE 5 (ABI5) from Arabidopsis was selected for further analysis. The results showed that transgenic Arabidopsis overexpressing DcaABI5 could rescue the ABA-insensitive phenotype in the mutant abi5 . Collectively, these findings will provide valuable information on AREB/ABF genes in orchids.