Cloning and characterization of mevalonate pathway genes in a natural rubber producing plant, Hevea brasiliensis

Hevea brasiliensis Mull. Arg. is a tree that produces natural rubber, an industrially vital isoprenoid polymer. Biosynthesis of natural rubber is known to take place biochemically by a mevalonate (MVA) pathway, but molecular biological characterization of related genes has been insufficient. From H. brasiliensis, we obtained full-length cDNA of genes encoding all of the enzymes that catalyze the six steps of the MVA pathway. Alignment analysis and phylogenetic analysis revealed that in H. brasiliensis there are three acetyl-CoA acetyltransferase genes, two HMG-CoA synthase (HMGS) genes, and four HMG-CoA reductase (HMGR) genes. Gene expression analysis by type of tissue indicated that MVA pathway genes were highly expressed in latex, as compared to other types of tissue and that HMGS and HMGR, which exist in multiple copies, have different expression patterns. Moreover, these MVA pathway genes in H. brasiliensis were found to complement MVA pathway deletion mutations in yeast.