Most previous studies have focused on the diversity and species richness of microbial communities, however, understanding the interactions between species and detecting key functional members of the community can help us better understand how microorganisms perform their functions. In this study, the response of the rice plant microbial community to the inoculation of cadmium-resistant endophytic bacterium R5 (Stenotrophomonas) was investigated for the first time using a microbial phylogenetic molecular ecological network. The results showed that inoculation of R5 changed the topological characteristics of the microbial network in rice plants, with the resulting network displaying stronger complexity and interaction in roots and aboveground parts, indicating that inoculation of R5 provided favorable conditions for microbial interactions. In addition, these interactions may be related to the absorption and transportation of cadmium by rice. Under the exogenous addition of R5, the network interactions of the rice plant microbial community were more inclined to cooperation. Both in the roots and aboveground parts of rice, the plant Cd content showed a decrease as the complexity and connectivity of the network increased, suggesting that complex microbial networks may be more beneficial to rice than simple microbial networks because as they were more adaptive and resistant to unfavorable environments. After inoculation with the R5 strain, the negative interaction with Cd content in rice plants increased significantly, and there might be more synergy between the microbial community and plants to jointly inhibit the absorption and transportation of Cd.
Keywords: Cadmium-tolerant strains; Keystone species; Microbial interactions; Microbial networks; Rice cadmium content.
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