To study the photosynthesis of Dendrobium officinale,we isolated a full-length cDNA of Rubisco activase DORCA(Accession No.KT205841) from this plant by the method of RT-PCR and RACE using degenerate primers designed according to the conserved region of RCA.The full-length cDNA of DORCA was 1 724 bp,with an ORF of 1 317 bp encoding 438 putative amino acids.Phylogenetic analysis showed that DORCA closed to ZaRCA(AAK25801.1).Bioinformatics analysis showed that DORCA belonged to β isoform of RCA protein and had high identities with other plant RCAs.The DORCA contained a predicted N-terminal transit peptide to chloroplast,two high conserved ATP-binding domains and multiple phosphorylation sites.The real-time quantitative PCR(qRT-PCR) results showed that DORCA was only detected in green tissues.In the 12 h dark and 12 h natural light photoperiods,maximal and minimal DORCA mRNA expression levels were detected at 8:30 and 20:30,respectively,which indicated that DORCA has the obvious characteristics of light-induced expression.