AUTHOR=Chu Honglong , Wang Haihua , Zhang Yanan , Li Zhumei , Wang Chunyan , Dai Dongqin , Tang Ming 

TITLE=Inoculation With Ectomycorrhizal Fungi and Dark Septate Endophytes Contributes to the Resistance of Pinus spp. to Pine Wilt Disease

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.687304

DOI=10.3389/fmicb.2021.687304

ISSN=1664-302X

ABSTRACT=<p>Pine wilt disease (PWD) is a deadly disease to pines (<italic>Pinus</italic> spp.) worldwide. The occurrence of PWD can reduce the relative abundance of root ectomycorrhizal fungi (ECMF) and dark septate endophytes (DSE). However, the effects of exogenous ECMF/DSE inoculation on the rhizosphere microbial community structure of <italic>Pinus tabulaeformis</italic> infected by pine wood nematode (PWN) is little known. Here, we tested how ECMF/DSE may improve resistance to PWD by quantifying microbial carbon biomass and soil enzymatic activity among different treatments at 6 and 9 months after PWN infection. Denaturing gradient gel electrophoresis (DGGE) was used to study the microbial community structure at 3, 6, and 9 months after PWN infection in the rhizosphere of <italic>P. tabulaeformis</italic> seedlings inoculated with ECMF/DSE. The results showed that exogenous ECMF/DSE inoculation reduced the disease severity caused by PWN infection. After PWN infection, the rhizosphere microbial carbon of seedlings inoculated with <italic>Amanita vaginata</italic>, <italic>Suillus bovinus</italic>, <italic>Gaeumannomyces cylindrosporus</italic>, and <italic>Paraphoma chrysanthemicola</italic> was 38.16, 49.67, 42.11, and 96.05% higher than that of the control group, respectively. Inoculation of ECMF/DSE inhibited the decrease of rhizosphere microbial biomass caused by PWN infection. The richness and diversity of <italic>P. tabulaeformis</italic> rhizosphere fungi at 9 months were reduced by PWN infection but partially recovered by the exogenous fungi (ECMF/DSE) inoculation except for <italic>P. chrysanthemicola</italic>, which indicates a role of ECMF/DSE in maintaining stability of the microbial community. Inoculation with ECMF/DSE increased the beneficial bacterial (<italic>Thauera</italic> sp., <italic>Mesorhizobium</italic> sp., etc.) and fungal groups (<italic>Tomentella ellisii</italic>, <italic>Wilcoxina mikolae</italic>, etc.) of in the rhizosphere. In summary, exogenous ECMF/DSE inoculation could increase <italic>P. tabulaeformis</italic> resistance to PWD probably by improving the rhizosphere microenvironment.</p>