Genome-Wide Identification of AP2/ERF Transcription Factor Family and Functional Analysis of DcAP2/ERF#96 Associated with Abiotic Stress in Dendrobium catenatum .

APETALA2/Ethylene Responsive Factor ( AP2/ERF ) family plays important roles in reproductive development, stress responses and hormone responses in plants. However, AP2/ERF family has not been systematically studied in Dendrobium catenatum . In this study, 120 AP2/ERF family members were identified for the first time in D. catenatum , which were divided into four groups ( AP2 , RAV , ERF and DREB subfamily) according to phylogenetic analysis. Gene structures and conserved motif analysis showed that each DcAP2/ERF family gene contained at least one AP2 domain, and the distribution of motifs varied among subfamilies. Cis-element analysis indicated that DcAP2/ERF genes contained abundant cis-elements related to hormone signaling and stress response. To further identify potential genes involved in drought stress, 12 genes were selected to detect their expression under drought treatment through qRT-PCR analysis and DcAP2/ERF#96 , a nuclear localized ethylene-responsive transcription factor, showed a strong response to PEG treatment. Overexpression of DcAP2/ERF#96 in Arabidopsis showed sensitivity to ABA. Molecular, biochemical and genetic assays indicated that DcAP2ERF#96 interacts with DREB2A and directly inhibits the expression of P5CS1 in response to the ABA signal. Taken together, our study provided a molecular basis for the intensive study of DcAP2/ERF genes and revealed the biological function of DcAP2ERF#96 involved in the ABA signal.