Effects of carbohydrates, ethanol and selected cell wall phenolics on in vitro growth of necrotrophic fungi--Heterobasidion annosum and Fusarium avenaceum.

摘要

In this study, a comparative assessment was undertaken of nutritional factors that are likely to influence in vivo growth of the S and P-types of necrotrophic root rot fungus Heterobasidion annosum and of the damping off pathogen Fusarium avenaceum respectively. The results indicate that glucose and fructose but not cellobiose or sucrose supported growth of these fungi when used as sole carbon source. Particularly for P-types and F. avenaceum, however, the utilization of cellobiose and sucrose was considerably enhanced by several fold in the presence of ethanol. In addition, key plant cell wall phenolics (ferulic acid, caffeic acid, p-coumaric acid) at 0.025% inhibited growth of the test fungi. But this toxicity was reversed in the presence of exogenously added cell wall sugars (glucose, fructose, sucrose, cellobiose) except for the P-types where sucrose addition was apparently slightly effective. Similarly, ethanol whether alone or in combination with the phenolics was poorly utilized except for F. avenaceum. The importance of these results in understanding factors influencing growth and development during pathogenesis of the necrotrophs on their conifer hosts is discussed.