ANTIFUNGAL COMPOUNDS IN ASPEN - EFFECT OF WATER-STRESS

A thin layer chromatography bioassay was used to detect antifungal compounds in tissue culture plantlets and potted seedlings of aspen. Catechol and the phenolic glycosides salicin and salicortin were identified as inhibitory compounds; a fourth compound was observed but was not identified. Inhibitory compound levels were estimated in eight tissue culture clones grown on unamended media and media amended with 0.22 M mannitol to induce water stress. Aspen tissue culture plantlets grown under water stress conditions had significantly lower levels of catechol, salicortin, and salicin. Significant clonal variation in levels of catechol, salicin, and the unidentified compound was also observed. Catechol, salicortin, and salicin were inhibitory to Hypoxylon mammatum when tested at levels similar to those employed in the thin layer chromatography bioassay. These results suggest that a reduction in the levels of inhibitory compounds in water-stressed aspen may be a factor in the water stress induced susceptibility of aspen to H. mammatum.