摘要：Sandalwood (
Santalum album L.) is highly valued for its fragrant heartwood and extracted oil. Santalols, which are the main components of that oil, are terpenoids, and these are biosynthesized via the mevalonic acid (MVA) pathway. Mevalonate kinase (MK) and phosphomevalonate kinase (PMK) are key enzymes in the MVA pathway. Little is known about the genes that encode MK and PMK in
S. album or the mechanism that regulates their expression. To isolate and identify the functional genes involved in santalol biosynthesis in
S. album, an
MK gene designated as
SaMK, and a
PMK gene designated as
SaPMK, were cloned from
S. album. The sequences of these genes were analyzed. A bioinformatics analysis was conducted to assess the homology of
SaMK and
SaPMK with
MK and
PMK genes from other plants. The subcellular localization of
SaMK and
SaPMK proteins was also investigated, as was the functional complementation of
SaMK and
SaPMK in yeast. Our results show that the full-length cDNA sequences of
SaMK and
SaPMK were 1409 bp and 1679 bp long, respectively.
SaMK contained a 1381 bp open reading frame (ORF) encoding a polypeptide of 460 amino acids and
SaPMK contained a 1527 bp ORF encoding a polypeptide of 508 amino acids.
SaMK and
SaPMK showed high homology with
MK and
PMK genes of other plant species. Functional complementation of
SaMK in a MK-deficient mutant yeast strain YMR208W and
SaPMK in a PMK-deficient mutant yeast strain YMR220W confirmed that cloned
SaMK and
SaPMK cDNA encode a functional MK and PMK, respectively, mediating MVA biosynthesis in yeast. An analysis of tissue expression patterns revealed that
SaMK and
SaPMK were constitutively expressed in all the tested tissues.
SaMK was highly expressed in young leaves but weakly expressed in sapwood.
SaPMK was highly expressed in roots and mature leaves, but weakly expressed in young leaves. Induction experiments with several elicitors showed that
SaMK and
SaPMK expression was upregulated by methyl jasmonate. These results will help to further study the role of
MK and
PMK genes during santalol biosynthesis in
S. album.
