Black Truffles Affect Physiology and Root-Associated - and -Type Denitrifying Bacterial Communities in the Initial Stage of Inoculation.

Truffles ( spp.) are edible ectomycorrhizal fungi with high economic value. Bacteria in ectomycorrhizosphere soils are considered to be associated with the nutrient uptake of truffles and hosts. Whether spp. inoculation can affect the growth of , the ectomycorrhizosphere soil, and the rhizosphere and -denitrifier communities at the ectomycorrhizae formation stage is still unclear. Therefore, we inoculated with the black truffles and , determined the physiological activity and morphological indices of seedlings, analyzed the physicochemical properties of ectomycorrhizosphere soils, and applied DNA sequencing to assess the and - denitrifier community structure in ectomycorrhizosphere soils. Peroxidase activity was higher in the seedlings inoculated with than in the inoculation and uninoculated control treatments. The available phosphorus contents were lower and nitrate contents were higher in those with truffle inoculation, and treatment differed more from the control than the treatment. The richness of the -community was highest in the treatment and lowest in the uninoculated treatment. The differences in -community composition across treatments were not statistically significant, but the communities were different. The -type bacteria correlated with three environmental factors (pH, available phosphorus, and nitrate contents), whereas the -type bacteria were only associated with the nitrate contents. Generally, this work revealed that inoculation with spp. would change a few nutrient contents and richness of -type bacteria and had little effects on growth of seedlings in the initial stage of inoculation. The results of this study may provide in-depth insights into the relationships between spp. and hosts, which should be taken into account when developing truffle production methods.