3-Hydroxy-3-methylglutaryl coenzyme A reductase genes from Glycine max regulate plant growth and isoprenoid biosynthesis

Isoprenoids, a large kind of plant natural products, are synthesized by the mevalonate (MVA) pathway in the cytoplasm and the 2-C-methyl- d -erythritol 4-phosphate (MEP) pathway in plastids. As one of the rate-limiting enzymes in the MVA pathway of soybean ( Glycine max ), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is encoded by eight isogenes ( GmHMGR1–GmHMGR8 ). To begin, we used lovastatin (LOV), a specific inhibitor of GmHMGR, to investigate their role in soybean development. To further investigate, we overexpressed the GmHMGR4 and GmHMGR6 genes in Arabidopsis thaliana . The growth of soybean seedlings, especially the development of lateral roots, was inhibited after LOV treatment, accompanied by a decrease in sterols content and GmHMGR gene expression. After the overexpression of GmHMGR4 and GmHMGR6 in A. thaliana , the primary root length was higher than the wild type, and total sterol and squalene contents were significantly increased. In addition, we detected a significant increase in the product tocopherol from the MEP pathway. These results further support the fact that GmHMGR1–GmHMGR8 play a key role in soybean development and isoprenoid biosynthesis.