Aims To study how ectomycorrhizas (ECMs) mediate plant performance and rhizosphere soil bacterial communities via altered physiological characteristics and root carbon exudation.Methods Tuber melanosporum-colonized and uncolonized Quercus mongolica seedlings were grown on a substrate consisting of 41 % peat, 41 % pumice, 9 % pine bark and 9 % lime. Gas exchange uorescence system, inductively coupled plasma atomic-emission spectrometer, high-performance liquid chromatography, gas chromatography and mass spectrometry, and 16S rRNA sequencing were used to analyze photosynthetic and nutritional characteristics, and rhizosphere carbon exudates, and bacterial communities.Results Tuber melanosporum mycorrhization increased leaf photosynthetic rate (by 69 %) and phosphorus concentration (94 %); increased rhizosphere pH (0.4 units), total organic carbon (TOC, 76 %) and acid phosphatase activity (33 %); but decreased leaf potassium concentration (26 %) and rhizosphere organic anions (50 %). Additionally, sugars like galactose were present in rhizosphere extract of colonized, but not uncolonized seedlings. Mycorrhization altered rhizosphere bacterial communities, with only ~10 % operational taxonomic units (OTUs) shared by both colonized and uncolonized seedlings; T. melanosporum enriched the phylum actinobacteria and the OTU of amb-16S-1323, IMCC26256 and PLTA13, but reduced SWB02. The abundances of different OTUs were differently affected by T. melanosporum colonization, and they were correlated with different physiological and/or rhizosphere factors.
ConclusionOur results demonstrate that T. melanosporum ECM colonization can regulate carbon economy and rhizosphere bacterial communities of Q. mongolica seedlings grown in a previously sterilized peat-based substrate, to promote plant growth and nutrient cycling.