Cloning and Expression Analysis of Mevalonate Kinase and Phosphomevalonate Kinase Genes Associated with MVA Pathway in Santalum Album

Abstract Sandalwood is highly valued for its fragrant heartwood and its extracted oil. The major oil component santalols are terpenoids, which are biosynthesis through the MVA pathway. MK and PMK are the major enzymes on the MVA pathway. Little is known about the genes encoding MK and PMK in Santalum album on its expression regulation mechanism. The analysis of MK and PMK genes and their functions are important for the further study of the biosynthesis of santalol. These results will help to further study the role of MK and PMK genes in S. album santalol biosynthesis. The total RNA of sandalwood leaves was extracted, then the First-strand cDNA synthesis was obtained through the PrimeScript first-strand cDNA synthesis kit. Then sequence comparison and bioinformatics analyses of the genes homology of SaMK and SaPMK with MKs and PMKs, We also investigated subcellular localization of SaMK and SaPMK proteins. Its functional complementation of SaMK and SaPMK in yeast were also investigated. Atlast, MeJA was used to induce tissue-specific analysis and expression profiles of SaMK and SaPMK. The results showed that the full-length cDNA sequences of SaMK and SaPMK were 1409 bp and 1679 bp containing a 1381 bp open reading frame (ORF) encoding a polypeptide of 460 amino acids and a 1527 bp ORF encoding a polypeptide of 508 amino acids, respectively. Sequence comparison and bioinformatics analyses indicated that SaMK and SaPMK showed high homology with MKs and PMKs, respectively from other plant species. Further functional complementation of SaMK in an MK-deficient mutant yeast strain YMR208W and SaPMK in a PMK-deficient mutant yeast strainYMR220W confirmed that cloned SaMK and SaPMK cDNA encode a functional MK and PMK, respectively and mediated MVA biosynthesis in yeast. Tissue expression pattern analysis revealed that SaMK and SaPMK were constitutively expressed in all the tested tissues. SaMK was highly expressed in young leaves but least expressed in sapwood while SaPMK was highly expressed in roots and mature leaves, and least expressed in young leaves.