Japanese oak wilt (JOW) is a disease that affects Quercus serrata and causes large-scale forest die-back. This disease is spread by the beetle Platypus quercivorus, which carries the fungus Dryadomyces quercivorus into trees. When infected, Q. serrata trees produce polyphenolic compounds as a defense against the fungus. However, these compounds can accumulate and block the tree’s water transport, ultimately leading to its death. This study explores how these polyphenols impact the structure of fungal decomposer communities and the wood decay process.
This research was carried out across three sites in Japan (Miyagi, Kyoto, Miyazaki), by setting logs of Q. serrata killed by JOW and of the apparently healthy stem as a control, and monitoring them over time. The sampling was conducted in autumn 2016 with 20 JOW logs and 20 healthy logs per site. Wood samples were taken from the top and bottom of each log using an electric drill. The results show that polyphenol levels are significantly higher in JOW logs than in healthy logs at the Miyagi site. We used non-metric multidimensional scaling (NMDS) and constrained ordination analyses to examine how polyphenol levels, fungal communities, and log characteristics interact. The results suggest that shifts in fungal composition are associated with high polyphenol levels, likely due to polyphenols' known antimicrobial properties. The difference in microbial community composition could affect the wood decomposition rates.