The colonization of the arbuscular mycorrhizal fungus Rhizophagus irregularis affects the diversity and network structure of root endophytic bacteria in maize

Arbuscular mycorrhizal fungi (AMF) can promote plant growth by interacting with a complex community of endophytic bacteria. However, the effect of AMF colonization on root endophytic bacteria communities in maize remains unclear. Pot experiment was conducted on maize with or without Rhizophagus irregularis inoculum to explore the effect of AMF on the root endophytic bacterial community diversity and network structure, and its potential to promote plant growth. The present results indicated that inoculation of R. irregularis significantly increased maize growth, and the colonization rate of R. irregularis from pot culture was significantly higher than that produced from dual in vitro culture system. Moreover, the inoculation of R. irregularis significantly enhanced the diversity of the endophytic bacterial community and the number of species with significantly different abundance (biomarkers). Network analysis showed that inoculation increased the complexity, modularity and compactness of the microbial community network, which was positively correlated with the colonization rate. However, the degree of symbiosis between communities showed an opposite trend to the number of key members. Structural equation model exhibited AMF inoculation affected microbial community diversity, and both AMF inoculation and microbial community diversity and function directly affected maize growth. The present study indicated that AMF may indirectly promote plant growth by recruiting some endophytic bacteria to change the structure of the root microbial community, which may contribute to further understand the functions and applications of AMF in crop growth.