Backgrounds: Previous studies have shown that host development has a profound impact on the structure and function of microbial communities, and elucidating such influence characteristics was of great significance for rational utilization of soil microbial resources and construction of functional microbial communities. However, we still lack more evidence to prove such influence characteristics. To this end, we collected soil samples at three different stages of development under two farming patterns in the semi-arid region of the Loess Plateau. Based on amplicon sequencing and metagenomics, we studied the effects of plant development on soil microbial community assembly patterns and multi-nutrient cycles characteristics, furthermore, sought evidence of soil keystone species promoting plant growth by constructing synthetic community.
Results: Adonis results showed that plant development shaped the structure and function of rhizosphere microbial communities. Furthermore, we found that microbial community assembly under intercropping pattern was more consistent which affected by homogeneous selection from the rhizosphere, with little change in dominant community composition. Bacterial community under monocropping pattern was more affected by deterministic processes at early stage, while some beneficial bacteria such as Actinomycetes and Rhizobiaceae were significantly enriched. Fungal community had the similar assembly pattern at late growth stages, while Ascomycetes were significantly enriched. Network analysis showed that the co-occurrence network was large at silking stage and the interactions between microorganisms were complex. The number of fungal nodes increases at later stage network, which increased competition among microbial taxa. The functional network was larger at jointing stage and the functional diversity was significantly higher than other two stages, and the abundance of functional genes related to labile carbon degradation, nitrogen cycle and phosphorus cycle was increased, while the abundance of carbon fixed genes was increased at the middle and later stages of plant growth. At the same time, we constructed a synthetic community based on the keystone microbial groups which isolated from the soil, and the results showed that the application of the synthetic community significantly increased the plant biomass.
Conclusions: In summary, our study revealed that host development play important roles in maintaining the structure and function of soil microbial communities, and soil keystone microorganisms played an important role in regulating plant growth, which may lay the foundation for manipulating soil microbiome to achieve sustainable agricultural development.