RESUMO
Chorismate mutase catalyzes the conversion of chorismate to prephenate that is the first committed step in the biosynthesis of the aromatic amino acids phenylalanine and tyrosine. A chorismate mutase gene, designated SmCM1, was isolated from Salvia miltiorrhiza by using RT-PCR. The full length of SmCM1 cDNA consists of 948 nucleotides and has an open reading frame of 765 bp. The deduced amino acid sequence of SmCM1 has 255 amino acid residues which forms a 36.0 kD polypeptide with calculated pI of 6.41 as expected. The putative polypeptide contains a CM_2 super family function domain. Blast W results showed that SmCM1 had 70% of the similarity with Petunia x hybrid CM, 72% of the similarity with Arabidopsis thaliana CM, and 64% of similarity with Populus trichocarpa CM. The transcription level of SmCM1 in root, stem and leaf was analysed by realtime quantitative PCR. The results showed the expression level of the SmCM1 in leaf was highest, and lowest in root. Yeast extract and silver ion joint induction could markedly stimulate the increase of mRNA expression of SmCM1 and its upstream 3-deoxy-7- phosphoheptulonate synthase (DAHPS) and chorismate synthase (CS). It was 7.9, 5.5 and 9.8 times of control on 8 h after induction, respectively.