Influence of wood durability on the suppressive effect of increased temperature on wood decay by the brown-rot fungus Postia placenta

Local climate conditions have a major influence on the biological decomposition of wood. To examine the influence of different temperature regimes on wood decay caused by the brown rot fungus Postia placenta in wood with differing natural durability, sapwood (sW) and heartwood (hW) of Scots pine, inoculated mini-blocks were incubated for up to 10 weeks at temperatures conducive or above optimal to wood decay. We profiled mass loss (ML) and wood composition, and accompanying changes in wood colonization and transcript level regulation of fungal candidate genes. The suppressive effect of suboptimal temperature on wood decay caused by P. placenta appeared more pronounced in Scots pine hW with increased durability than in sW with low decay resistance. The differences between sW and hW were particularly pronounced for cultures incubated at 30 C: unlike sW, hW showed no ML, poor substrate colonization and marker gene transcript level profiles indicating a starvation situation. As brown rot fungi show considerable species-specific variation in temperature optima and ability to mineralize components that contribute to wood durability, interactions between these factors will continue to shape the fungal communities associated to wood in service.