| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2003: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Cultured roots of Menispermum dauricum produce and exude strigol, which stimulates germination of several species of the root parasitic genera Striga and Orobanche. The stimulant has been considered to be a sesquiterpene, based on its structure. Two pathways for terpenoid biosynthesis in higher plants, the methyl erithritol phosphate (MEP) pathway and the mevalonate pathway, have been established. Investigations into strigol biosynhesis, using cultured roots of M dauricum, showed that fosmidomycin, an inhibitor of MEP pathway, did not influence activity of M. dauricum root culture filtrate on Striga germination. Feeding M.dauricum cultured roots with [1-^<13>C] glucose and [2-^<13>C] mevalonolactone and subsequent monitoring of ^<13>C incorporation into strigol by ^<13>C-NMR spectroscopy showed no signal enrichment. HPLC purified extracts of cultured M. dauricum roots, previously fed with [2-^<14>C] mevalonolactone, displayed no detectable radioactivity in fractions showing high Striga germination inducing activity. It could thus be concluded that strigol is not synthesized by the mevalonate pathway. Strigol may be synthesized, as is abscisic acid, via carotenoids. Involvement of carotenoids in strigol biosynthesis is, currently, under investigation.
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