Abstract: Objective To obtain the full-length cDNA sequence of Glutaryl-CoA dehydrogenase(GCDH)gene and explore the potential functions of GCDH in the biosynthesis of cantharidin. Methods GCDH fragments were screened from the early constructed cDNA library, and the full-length cDNA sequence of the gene was amplified by RACE technique. The expression of GCDH in adults at different periods(5 days, 10 days, 15 days, 22 days, 25 days, 30 days)was determined with RT-qPCR. Blast comparison was conducted using online NCBI database, and structural biology prediction of GCDH was made using online resources. Results In this study, the full length cDNA sequence of GCDH 1 338 bp was obtained, and the entry number was MK370842. The open reading frame of GCDH was 1 260 bp and encodes 419 amino acid residues. Phylogenetic analysis results showed that the protein encoded by this gene was the closest phylogenetic relation to Trbolium castaneum(XP_971662). RT-qPCR results showed that the expression of this gene was different in male and female adults, and it was highly expressed in the early stage(15 d)of mass synthesis of cantharidin in males. Conclusion The GCDH in cantharidin may play an important role in cantharidin biosynthesis. Especially in males, GCDH is highly expressed in the early stage of cantharidin mass synthesis, which further suggests that amino acid metabolism may be closely related to cantharidin synthesis. These findings provide useful ideas and theoretical basis for further study of cantharidin biosynthesis mechanism and artificial cultivation of cantharidin with high content.

Key words: Glutaryl-CoA dehydrogenase, Mylabris cichorii, mechanism of cantharidin biosynthesis