ABSTRACT
Objective: To clone and characterize a basic helix-loop-helix (bHLH) transcription factor SmbHLH93 from Salvia miltiorrhiza, and to predict its probable function. Methods: SmbHLH93 was cloned by PCR and RT-PCR from genomic DNA and cDNA, while its 5' promoter region was cloned by BD Walking. Analysis on physico-chemical property, structure characteristic, and phylogenetic relationships of SmbHLH93 protein was carried out by bioinformatic method. Gene expression in different organs and inducing conditions was detected by qPCR. Results: Gene sequences of SmbHLH93 (954 bp) were obtained, including three introns and four exons, and the open reading frame was 657 bp, encoding 218 amino acids. Its promoter region had 1 583 bp nucleotides. The putative SmbHLH93 protein contains bHLH and ACT_UUR-ACR-like domains, without transmembrane helices, and located in the nucleus. The gene expression was highest in roots and lowest in stems. With the development of flowers, its expression decreased gradually. Light and low temperature could induce high expression of SmbHLH93, while salicylicacid (SA) inhibited its expression. Conclusion: A new member of bHLH transcription factor, SmbHLH93, is cloned from S. miltiorrhiza, and it could be involved in the development of flower and regulation of secondary metabolic pathways in S. miltiorrhiza.