Effects of Oak Wilt Disease on Fungal Community Composition and Wood Decomposition in Dead Quercus serrata Trunks

概要

Poster
Poster 10

Effects of Oak Wilt Disease on
Fungal Community Composition and Wood Decomposition
in Dead Quercus serrata Trunks
Satsuki KIMURA1, Yu FUKASAWA1, Yuji KOMINAMI2, Masahiro TAKAGI3, Kimiyo MATSUKURA4,
Masayuki USHIO5, Makoto KOBAYASHI6, Satoshi SUZUKI7, Shuhei TAKEMOTO7, Nobuaki TANAKA7,
Mayuko JOMURA4, Kohmei KADOWAKI8, Haruo KINUURA2 and Satoshi YAMASHITA2
1

Tohoku University
Forestry and Forest Products Research Institute
3
University of Miyazaki
4
Nihon University
5
The Hong Kong University of Science and Technology
6
Hokkaido University
7
The University of Tokyo
8
Kyoto University
2

In Japan, mass attacks of an ambrosia beetle Platypus quercivorus, vectoring a pathogenic fungus Raffaelea quercivora, cause
oak wilt outbreaks in recent decades. Since P. quercivorus inoculates symbiotic fungi into wood tissue, it can alter the fungal
community composition within the dead wood. A change in the fungal community composition may alter the decomposition function
of the community, as well as the physical and chemical properties of the dead wood. The difference in properties of the dead wood
may impact surrounding biological communities. Therefore, understanding the effects of oak wilt disease on a dead wood fungal
community is important for predicting wood decomposition and forest biodiversity after the dieback. In this study, we used DNA
metabarcoding to compare the fungal communities between Q. serrata trunks killed by oak wilt and healthy trunks that felled
artificially at three sites across latitude in Japan. A total of 1200 samples from 5-time points during the 2016 autumn – 2018 spring
were subjected to amplicon sequencing of the fungal internal transcribed spacer 1 region and 1128 fungal operational taxonomic
units (OTUs) were detected. Fungal community composition differed significantly between Q. serrata trunks killed by oak wilt
and healthy-cut trunks (Fig. 1), and diversity indices showed that trunks killed by oak wilt were significantly lower than that of
healthy-cut trunks (Fig 2). The Fungal Trait database was used to estimate the function of each OTU and revealed a dominance of
wood-decomposing fungi, mainly white rot fungi, which have the ability to decompose wood. The generalized linear mixed model
(GLMM) showed that the OTU richness and DNA copy number of white rot fungi were significantly affected by the sampling period,
mean air temperature, precipitation, and oak wilt infestation, and that the OTU richness and DNA copy number of white rot fungi
increased with oak wilt. During the ca. 1.5-year experiment, wood density decreased by an average of 9.2%. Structural equation
modeling (SEM) showed that oak wilt and environmental variables significantly affected the fungal community, but the fungal
community didn’t significantly affect wood decomposition (Fig 3). Rather, trunk moisture and mean air temperature strongly affected
decomposition. This study focused on the initial decomposition of the trunks during ca. 1.5 years after the start of the experiment. It is
important to conduct further research over a longer time period to evaluate the effects of oak wilt and associated fungal communities
on trunk decomposition.

Figure 2. Diversity index

Figure 1. Relative abundance of fungi (functional group)
Figure 3. ...

この論文で使われている画像