The mechanism of promoting rhizosphere nutrient turnover for arbuscular mycorrhizal fungi attribute to recruited functional bacterial assembly

Symbiosis with arbuscular mycorrhizal (AM) fungi improves plant nutrient capture from the soil, yet there is limited knowledge about the diversity, structure, functioning, and assembly processes of AM fungi-related microbial communities. Here, 16S rRNA gene sequencing and metagenomic sequencing were used to detect bacteria in the rhizosphere of Lotus japonicus inoculated with and without AM fungi, and the L. japonicus mutant ljcbx (defective in symbiosis) inoculated with AM fungi in southern grassland soil. Our results show that AM symbiosis significantly increased bacterial diversity and promoted deterministic processes of bacterial community construction, suggesting that mycorrhizal symbiosis resulted in the directional enrichment of bacterial communities and established a stable rhizosphere bacterial community. AM fungi promoted the enrichment of nine bacteria, including Ohtaekwangia, Niastella, Gemmatimonas, Devosia, Sphingomonas, Novosphingobium, Opitutus, Lysobacter, Brevundimonas..., Greenhouse experiments
Experiment 1 was designed to explore whether AM fungi inoculation affected the bacterial community in the rhizosphere. The factorial experimental design included the addition of AM fungi and the non-addition of AM fungi (CK). Lotus japonicus (Miyakojima MG20) plants were selected and grown at 22°C to 24°C under a 16-h-day/8-h-night cycle. We collected soil samples from a southern grassland in Zhaotong, Yunnan Province, Southwest China (103°63′E, 27°66′N; Figure S1). The dominant native AM fungi in this soil were Acaulospora, as identified using special primers (Lee et al., 2008; Sato et al., 2005; Zhang et al., 2021) (Table S1). Surface soil (0–20 cm) was collected using a “five points” sampling strategy in a 25 m × 25 m field area. Soils were immediately transported for storage at 4°C. Soils were dried sufficiently to pass through a 2-mm sieve and plant tissues were removed. Soil samples were divided into two parts: one portion was used for chemical analysis, and..., Data analysis
All analyses and data visualization were performed in R version 3.6.0 (Hu et al., 2022; Team, 2019). Differences in the alpha diversity richness were estimated using one-way and two-way ANOVAs. Differences in the taxonomic composition of bacterial communities were visualized using non-metric multidimensional (NMDS) analyses. Alpha diversity and NMDS were calculated using the ‘vegan’ package (version 2.0-10) (Oksanen et al., 2013) in R. To describe potential co-occurrence between all OTUs in the rhizosphere, co-occurrence networks of each sample were constructed using the ‘cooccur’ package in R. Using psych package in R, the genus level abundance matrix was transformed into species correlation matrix. Then, the Gephi (https://gephi.org/) was used to calculate the information of nodes and edges of the network. At last, network characteristic data was exported to draw figures. For Sloan neutral model (Rezki et al., 2017; Sloan et al., 2006) 95% binomial confidence intervals f..., # The mechanism of promoting rhizosphere nutrient turnover for arbuscular mycorrhizal fungi attribute to recruited functional bacterial assembly

Brief summary of dataset contents, contextualized in experimental procedures and results:

Symbiosis with arbuscular mycorrhizal (AM) fungi improves plant nutrient capture from the soil, yet there is limited knowledge about the diversity, structure, functioning, and assembly processes of AM fungi-related microbial communities. Here, 16S rRNA gene sequencing and metagenomic sequencing were used to detect bacteria in the rhizosphere of Lotus japonicus inoculated with and without AM fungi, and the L. japonicus mutant ljcbx (defective in symbiosis) inoculated with AM fungi in southern grassland soil. Our results show that AM symbiosis significantly increased bacterial diversity and increased deterministic processes of bacterial community construction, suggesting that mycorrhizal symbiosis resulted in the directional enrichment of bacterial commu...