Conservation tillage decreases selection pressure on community assembly in the rhizosphere of arbuscular mycorrhizal fungi

Different tillage practices elicit various degrees of soil disturbance and significantly affect the community structure of soil microbes, especially rhizosphere microbes. However, little is known about the effects of tillage on community assembly and composition in the rhizosphere of arbuscular mycorrhizal fungi (RAMF). In this study, we investigated wheat RAMF communities under long-term different tillage patterns in an agroecosystem. The results showed that soil disturbance caused by tillage resulted in significant changes in RAMP communities, and this change varied with the degree of disturbance. Soil total nitrogen was the most relevant abiotic factor to RAMP communities. Notably, as a biotic selection factor, we found that cohesion of communities could also explain the changes in RAMF taxonomic and phylogenetic composition, which have not been revealed by other studies. Meanwhile, by analyzing the RAMF community assembly process under tillage practices, we found that stochastic processes dominated the assembly of RAMF communities under different tillage practices, and with the reduction of disturbance degree, the process occupied an increasingly important position. Overall, the structure and assembly process of the RAMF community in the rhizosphere varied with the degree of soil disturbance caused by tillage. These findings may provide more insights on underground processes and aid in the development of conservation tillage as a sustainable agricultural practice. (C) 2019 Elsevier B.V. All rights reserved.