The Methylerythritol Phosphate Pathway Contributes to Strigolactone Biosynthesis

Abstract

Strigolactones are endogenous growth regulators that inhibit shoot branching, as well as being communication signals for symbiosis and parasitism in the rhizosphere. Studies using chemical inhibitors and mutants have suggested that strigolactones are biosynthesized from carotenoids. However, the isoprenoid origin of the strigolactone carbon skeleton has not been proved directly in a metabolism study. To address this question, a ¹³C-labeled precursor specific to the mevalonate or methylerythritol phosphate (MEP) pathway was fed to Lotus japonicus cultured roots in the presence of a chemical inhibitor that blocks each endogenous pathway. We found that ¹³C-deoxyxylulose, but not ¹³C-mevalonolactone, was efficiently incorporated into 5-deoxystrigol, indicating that the MEP pathway principally provides isoprene units to strigolactones.