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Although they are a valuable edible ectomycorrhizal fungus, truffles (Tuber spp.) nevertheless face significant difficulties in the development of their scale. As a type of high economic value nut-like economic forest tree, the pecan (Carya illinoinensis) serves as a natural host for truffles. However, the technology for mycorrhizal synthesis in pecan has not yet been developed, and it is still unclear how certain microbes affect this process. In this study, we inoculated the pecan root system with a suspension of truffle spores and investigated the growth physiology of pecan seedlings with various infestation levels, as well as changes in the soil's physicochemical properties and the makeup of the microbial community at the root level. The findings showed that tuber inoculation significantly increased the peroxidase activity of the pecan root system, significantly decreased the pH, and effective phosphorus content of mycorrhizosphere soil, while increasing the nitrate nitrogen content, and significantly increased the abundance and diversity of the mycorrhizosphere soil fungal community. Different groups of fungal and bacterial markers were formed in the mycorrhizosphere of pecan seedlings at different levels of infestation. In the highly infested group, Rozellomycota and lasiosphaeriaceae were the difference marker fungi, and Xanthobacteraceae, Rhizobiaceae as well as Streptococcaceae were the difference marker bacteria. In the low-infestation group, sphaerosporella was differential marker fungi, and Bacillus and Tumebacillus were differential marker bacteria. The fungal marker flora of the control group consisted of Chaetomium and Gilmaniella. Pseudomonas was the marker bacterial community. Additionally, these fungi included Collarina and Rozellomycota, and several bacteria from the genera Pseudomonas, Gemmatimonas, and others showed highly significant relationships with changes in soil pH, effective phosphorus, and nitrate nitrogen. In conclusion, pecan–truffle mycorrhizal seedlings have the potential to create the ideal microbial community structure needed for mycorrhizal growth, and these microorganisms have the potential to significantly alter the pH, effective phosphorus content, and nitrate nitrogen concentration of the mycorrhizosphere soil. Our results contribute to the understanding of how the mycorrhizosphere microbial community evolves when exogenous mycorrhizal fungi infest host plants and can offer some theoretical guidelines for growing pecan–truffle mycorrhizal seedlings. [ABSTRACT FROM AUTHOR]

Black truffles andwhite truffles arewidely studied around theworld, but their effects on plant growth and physiological responses, and on the mycorrhizosphere bacterial community of the host plant remain unclear. Here, mycorrhizal colonization of Castanopsis rockii by Tuber indicum (Chinese black truffle) and T. lijiangense (Chinese white truffle), respectively, was induced in a greenhouse study, and their effects on host growth, physiological responses and mycorrhizosphere bacterial communities were compared. The results show that colonization of both Tuber species significantly increased leaf photosynthetic rate, leaf P concentration and mycorrhizosphere acid phosphatase activity, as well as richness of mycorrhizosphere bacterial communities of C. rockii seedlings. However, T. indicum colonization on the one hand significantly decreased tartrate content, bacterial acid phosphatase, phoC gene abundance in the mycorrhizosphere, and peroxidase (POD) activity of ectomycorrhizal root tips, but on the other hand increased mycorrhizosphere pH and superoxide dismutase (SOD) of ectomycorrhizal root tips, compared to T. lijiangense colonization. Moreover, principal coordinate and β-diversity analyses show significant differences in mycorrhizosphere bacterial community composition between T. indicum and T. lijiangese colonized C. rockii seedlings. Finally, the relative abundance of the bacterium Agromyces cerinus significantly correlated to mycorrhizosphere acid phosphatase activity and leaf P concentration, suggesting that this bacteriummight play an important role in P mobilization and acquisition. Overall, these results suggest that T. indicum and T. lijiangense differently regulate their host plant's physiological responses and mycorrhizosphere bacterial community. [ABSTRACT FROM AUTHOR]