Abstract: Plant MADS-box genes encode a family of highly conserved transcription factors which involved in many different developmental processes, including floral formation and flowering. To elucidate the molecular mechanisms of floral development in the monocotyledonous species Doritaenopsis hybrid, we isolated cDNA of a MADS-box gene from this plant by the method of 3′ and 5′ rapid amplification of cDNA ends using degenerate primers designed according to the MADS-box protein family conserved region from inflorescence rachis at flowering stage. The full length cDNA of this gene is 960 bp, with a 37 bp 5′ UTR, an ORF of 753 bp and 185 bp 3′ UTR encoding 245 putative amino acids. Sequence and phylogenetic analysis indicated a high degree of predicted protein sequence identity with those from other species. The gene belongs to the class of AP1/FUL-like group of MADS-box genes and was termed as DtpsMADS1(accession No.JQ065097). Real-time quantitative PCR (qRT-PCR) results showed that DtpsMADS1 had obvious expression specificity in different organs; DtpsMADS1 had higher levels of expression in root and leaf at pre-flowering stage and post-flowering stage, meanwhile had lower levels of expression at seedling stage and full-blossom stage; The expression of DtpsMADS1 in inflorescence rachis showed the same tendency as root and leaf; However, only trace expression level was detected in flower organs. The results suggested that DtpsMADS1 could be involved in regulating the flowering process, not in floral morphogenesis.

Key words: MADS-box gene, flowering process, RACE, phylogenetic tree, Doritaenopsis hybrid