Abstract: According to the sequencing result of caffeic acid O-methyltransferase from Salvia miltiorrhiza transcriptome database analysis, its specific primers were designed. By RT-PCR method, a novel COMT gene was isolated from S.miltiorrhiza, and named as SmCOMT1(Genebank accession number: JF693491). SmCOMT1, with full-length cDNA of 1 158 bp, includes an open reading frame of 1 095 bp which encodes a 364 amino acids polypeptide. Furthermore, a length of 2 275 bp sequence was also cloned by PCR from genomic DNA of S.miltiorrhiza. The genomic DNA of SmCOMT1, aligned with cDNA, contains four exons and three introns in the encoding region. The results of amino acid sequence analysis shows that deduced amino acid polypeptide contains all the conserved element of COMT family and it is highly homologous to COMT proteins from the same family of Ocimum basilicum with 89% identity. Phylogenetic tree analysis also indicates that SmCOMT1 is more related to the genetic relationship of COMT in dicotyledonous plants. Quantitative RT-PCR analysis revealed that SmCOMT1 was expressed in different organs, and was highly expressed in stem, and could be induced by methyl jasmonate (MeJA) and pathogen. These results showed that SmCOMT1 might be pathogen-responsive gene in plant defenses.

Key words: Salvia miltiorrhiza Bge., caffeic acid O-methyltransferase, gene clone, quantitative RT-PCR