Abstract
Median periods of saprophytic survival byGaeumannomyces graminis var.tritici in colonized wheat straws are shorter in clay-loams than in soils of lighter texture. This reduction has been ascribed to the microflora of clay-loam soils, and especially to competition by commensal bacteria for the sugars released by fungal cellulolysis of the wheat-straw tissue. Model experiments on the growth of colonies of four cereal foot-rot fungi on filter-paper in the presence of bacteria showed that the slowly growing colonies ofG. graminis var.tritici caused a loss in paper dry weight that was nearly five times as great, per unit area, as that by colonies ofFusarium culmorum, which grow four times as fast in the presence of bacteria. By their rapid uptake of sugars, commensal bacteria prevent the regulation of cellulase enzyme induction by catabolite repression, so that cellulolysis continues at a maximum rate. So this bacterial competition for sugars hastens exhaustion of the substrate and thus shortens survival of the take-all fungus.
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References
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Garrett, S.D. Effect of soil texture on microbial abbreviation of saprophytic survival by the take-all fungus of wheat. Proc. Indian Acad. Sci. 94, 85–90 (1985). https://doi.org/10.1007/BF03053128
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DOI: https://doi.org/10.1007/BF03053128