Terpene Biosynthesis inCell-free Extracts andExcised Shoots fromWedgwoodIris1

Excisedshootsand cell-free extractspreparedfrom Wedgwoodiris(Iris hollandica Hoog.Wedgwood) shoots metabolized '4C-labeled mevalonicacid(MVA).Byusingcellfreeextracts, theC fromMVA-1-`C was recovered as 'CO2, whilethatfromMVA-2VC was recovered as neutralterpenes, acid-hydrolyzable terpenes, or 4CO2. Also, underoptimal incubationconditions, 12.8nanomolesR-MVA-2-Cwas incorporated intoneutral terpenes permilligram freshweight per hour.In contrast, excisedshootsincorporated only0.58 nanomoles R-MVA-2-C per mg freshweight per hour.Labeled products identified fromthecell-free systemwere squalene, farnesol, geranylgeraniol, andcompounds thatare converted to farnesol and geranylgeraniol afteralkalinehydrolysis. Squalene anda 4,4-dimethylsterol were identified as products fromexcised shootsbutnot theterpenealcohoLs or the alkaline-hydrolyzable compounds.