ELEMENTAL SULFUR (S-8) IN HIGHER-PLANTS - BIOGENIC OR ANTHROPOGENIC ORIGIN

In the course of investigating lipophilic air pollutants in the epicuticular wax of Pinus sylvestris L. needles, elemental sulphur, S-8, was found in all samples. An investigation was conducted to determine the origin of this substance. No correlation between the level of S-8 in the needles and human activities in the sampling area could be found, contrary to what would have been expected of an anthropogenic compound. The internal lipids of P. sylvestris as well as the epicuticular wax of historical herbarium material and seedlings grown in clean, filtered air, and the epicuticular wax of several other species, both gymnosperms and angiosperms, also contained S-8. Quantitation of S-8 in P. sylvestris gave levels of 7.2 +/- 2.9 mu g/g wax, 3.8 +/- 1.9 mu g/g internal lipid and 0.43 +/- 0.17 mu g/g total needle dry weight. Almost 0.1% of the total sulphur in pine needles is S-8, and approximately half of the total S-8 is found in the wax. The results suggest that S-8 is endogeneous in many higher plants. A function for S-8 as part of an antifungal defence system is possible.