Different sensitivities and assembly mechanisms of the root-associated microbial communities of Robinia pseudoacacia to spatial variation at the regional scale

PurposeThe root microbiome accompanies plants throughout their growth cycle, helping plants absorb nutrients, resist disease and adapt to stressful environments. It is important to reveal the interaction and assembly of the forest root microbiome and the mechanism of its response to spatial variation.MethodsWe investigated the diversity, community assembly, and network associations of microbial communities in the endosphere and rhizosphere of Robinia pseudoacacia in three counties in the forest distribution area of the Loess Plateau using 16S rRNA gene high-throughput sequencing technology.ResultsEnvironmental factors affected the recruitment of root-associated microorganisms, and less mean annual precipitation (MAP) increased the difference between the rhizosphere and endosphere microorganisms. As MAP decreased, the co-occurrence network stability of the root fungal community was disrupted, while network instability of bacteria was not manifested. At the same time, MAP reduction reduced the external connectivity of different compartments of root-associated bacteria and fungi. Moreover, the assembly of the rhizosphere soil bacterial and endosphere fungal communities was dominated by stochastic processes, while the assembly of the endosphere bacterial and rhizosphere fungal communities was dominated by deterministic processes. As MAP decreases, the randomness of the assembly process of rhizosphere soil bacteria was significantly reduced.ConclusionsThe root -associated microbial communities of Robinia pseudoacacia have different sensitivities and assembly mechanisms to spatial variation. MAP is the main factor driving the stability, connectivity and assembly of root microbial communities of Robinia pseudoacacia in the Loess Plateau.