3-Hydroxy-3-methylglutaryl coenzyme A reductase(HMGR) is the first rate-limiting enzyme in the mevalonic acid(MVA)pathway and it is an important regulatory site in the metabolism of terpenoids in the cytoplasm. In this study, Siraitia grosvenorii that had been pollinated 0 day,1 day,3 days,15 days and 30 days were used as experimental materials. Based on the transcriptome data, two HMGR genes were cloned from S. grosvenorii cDNA and named SgHMGR2(GenBank Accession Numbers MT270447) and SgHMGR3(GenBank Accession Number MT270448). The two genes contain open reading frames(ORFs) of 1 746 bp and 1 782 bp, encoding 582 and 594 amino acids, and their molecular masses are estimated to be 62.7,63.2 kDa, respectively. Isoelectric point are 8.34 and 7.47, both of which do not contain signal peptides, are non-secretory proteins, and have two transmembrane structures. Combining the conserved regions of the proteins and the analysis of the evolutionary tree, it was confirmed that the genes are indeed HMGR family genes. Real-time PCR was used to detect the expression pattern of SgHMGRs at different times after pollination, and the highest expression level was 15 days after pollination. Finally, two full-length SgHMGRs were cloned from S. grosvenorii for the first time, and the differential expression of SgHMGRs at different times after pollination was revealed, providing a research basis for the mining of key enzyme gene elements in the biosynthesis pathway of S. grosvenorii terpenoids.
Keywords: 3-hydroxy-3-methylglutaryl coenzyme A reductase; Siraitia grosvenorii; bioinformatics; expression analysis.