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INITIATION OF TERPENOID SYNTHESIS IN OSMOPHORES OF STANHOPEA ANFRACTA (ORCHIDACEAE): A CYTOCHEMICAL STUDY

1987; Wiley; Volume: 74; Issue: 9 Linguagem: Inglês

10.1002/j.1537-2197.1987.tb08748.x

1537-2197

Kenneth J. Curry,

Plant Diversity and Evolution

The floral scent glands (osmophores) of Stanhopea produce a fragrance composed of terpenoids and aromatics which attract pollinators. The terpenoid component is composed of isoprene units synthesized via the mevalonic acid pathway. Localization of hydroxymethylglutaryl CoA synthase in the mevalonic acid pathway was achieved using a technique which elicits the formation of an electron‐dense precipitate of uranyl ferrocyanide at the point in the mevalonic acid pathway where an acetyl group from acetyl CoA is transferred to acetoacetyl CoA, releasing free CoA‐SH. Applying this technique to cells of the osmophore of 5. anfracta resulted in a precipitate between the inner and outer mitochondrial membranes, in the smooth endoplasmic reticulum, and, to a lesser extent, on the outer surface of the tonoplast membranes and between the inner and outer membranes and granal membranes of amyloplasts indicating multiple, subcellular locations for at least some enzymes in the mevalonic acid pathway. Localization of carnitine acetyltransferase by a similar technique resulted in a precipitate between the inner and outer mitochondrial membranes and in the smooth endoplasmic reticulum indicating multiple, subcellular locations for this enzyme also.