Elemental sulphur (S8) in higher plants — biogenic or anthropogenic origin

Abstract

In the course of investigating lipophilic air pollutants in the epicuticular wax ofPinus sylvestris L. needles, elemental sulphur, S8, was found in all samples. An investigation was conducted to determined the origin of this substance. No correlation between the level of S8 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 ofP. 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 S8. Quantitation of S8 inP. sylvestris gave levels of 7.2±2.9 μg/g wax, 3.8±1.9 μg/g internal lipid and 0.43±0.17 μg/g total needle dry weight. Almost 0.1% of the total sulphur in pine needles is S8, and approximately half of the total S8 is found in the wax. The results suggest that S8 is endogenous in many higher plants. A function for S8 as part of an antifungal defence system is possible.