ANTIFUNGAL COMPOUNDS IN ASPEN - EFFECT OF WATER-STRESS

A thin layer chromatography bioassay was used to detect antifungal com pounds in tissue culture plantlets and potted seedlings of aspen. Cate chol and the phenolic glycosides salicin and salicortin were identifie d 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 catech ol, salicortin, and salicin. Significant clonal variation in levels of catechol, salicin, and the unidentified compound was also observed. C atechol, salicortin, and salicin were inhibitory to Hypoxylon mammatum when tested at levels similar to those employed in the thin layer chr omatography bioassay. These results suggest that a reduction in the le vels of inhibitory compounds in water-stressed aspen may be a factor i n the water stress induced susceptibility of aspen to H. mammatum.