The Sauromatum guttatum appendix as an osmophore: excretory pathways, composition of volatiles and attractiveness to insects.

This report combines chemical, electron microscopic and ecological studies on the volatiles liberated by the Sauromatum guttatum appendix on D-Day, the day of inflorescence-opening and heat-production. More than 100 compounds from at least nine different chemical classes (monoterpenes, sesquiterpenes, fatty acids, ketones, alcohols, aldehydes, indole, and phenolic and sulphur compounds) are liberated during the thermogenic activity. The volatiles were identified using gas chromatography-mass spectrometry. Electron microscopy provides additional evidence that the endoplasmic reticulum (ER) interacts with the plasma membrane, creating novel routes of excretion of the volatiles to the exterior of the cell. It seems that the fusion event creates channels from the interior to the exterior of the cell. Furthermore, a multitubular body, conceivably originating in the ER, seems to fuse with the plasma membrane and to appear only on D-day. This multitubular body is closely associated with lipid bodies during heat-production and might be involved in the oxidation of lipids to volatile products. The foul odour produced by the appendix attracts at least 30 species of insects.