Mycorrhizal fungi alter root exudation to cultivate a beneficial microbiome for plant growth

Arbuscular mycorrhizal (AM) fungi traditionally form symbioses with most plant species. Although AM fungi have critical effects on microbial communities, the pathways showing how AM fungi shape rhizosphere bacterial communities and their functions are rarely explored. Through three systematic experiments, AM fungi-bacteria interactions were first investigated in the rhizosphere of Lotus japonicus, then the interactions were confirmed by a second experiment with wild-type and a mycorrhiza-defective mutant ljcbx of L. japonicus. The mechanisms were presented by adding core bacteria and AM fungi to the plant rhizosphere with the third experiment. We found that AM fungi-bacteria interactions enhanced host plant growth and identified a core bacterial group that uniquely enhanced host plant growth. Adding core bacteria and AM fungi promoted host growth and nutrient acquisition compared to adding AM fungi or core bacteria independently. Allelopathic substances secreted by AM fungal colonizing ..., Greenhouse experiments
Experiment 1 was designed to determine whether rhizosphere bacteria affected the plant growth-promoting effects of AM fungi in the greenhouse. The factorial experimental design included the addition of AM fungi and one soil with two treatments (sterilized and unsterilized). To sterilize the soil, the soil was autoclaved at 121°C for 1 h and the procedure was repeated after 2 days. Wild-type (WT) L. japonicus plants were selected. In the dark, surface-sterilized seeds of L. japonicus were grown on 0.8% agar for 5 days (d) and were then transferred into pots containing AM fungal inoculum.  Plants were grown at 22°C to 24°C under 16 hours of light: 8 hours of dark photoperiodic lighting for 40 d. The soil samples for the first experiment were collected from a southern grassland in Yunnan Province, China (103°63′E, 27°66′N). Each sample was extracted from a depth of 0–20 cm. The mean soil organic carbon content (SOC) was 60.8 g kg-1; the mean soil total nitrogen conte...,