Molecular Cloning and Expression Analysis of LcHMG3 Gene Encoding a 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase from Litchi chinensis

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) encoded by a small gene family, is known to be the rate-limiting enzyme in the mevalonic acid pathway for the biosynthesis of isoprenoid compounds. A novel LcHMG3 gene was isolated from litchi in this paper. The full-length cDNA of LcHMG3 was 1931 bp containing a 1638 bp ORF encoding 545 amino acids, with four typical HMGR domain features. Despite 77 and 72% sequence identity at the amino acid level with LcHMG1 and LcHMG2, respectively, LcHMG3 exhibited its distinct spatially and temporally expression characteristic during fruit development. LcHMG3 expression in both the pericarp and aril of the fully red cultivar 'Hehuadahongli', was much stronger than that of the unevenly red cultivar 'Feizixiao' during litchi fruit development; whereas there was no significant difference in fruits from early-anthesis (EA fruits) and late-anthesis (LA) fruits of 'Feizixiao' litchi. Moreover, thidiazuron (TDZ) could delay fruit colouration and decrease the expression of LcHMG3 in fruits, especially in the pericarp. Taken together, it is suggested that the LcHMG3 expression might be correlated with the pericarp colouration in litchi.