Dispersal Limitation Plays Stronger Role in the Community Assembly of Fungi Relative to Bacteria in Rhizosphere Across the Arable Area of Medicinal Plant.

Guozhuang Zhang,Yong Wang,Shilin Chen,Fugang Wei,Mingjun He,Zhongjian Chen,Guangfei Wei,Linlin Dong,Shuo Jiao

doi:10.3389/fmicb.2021.713523

Abstract

Understanding the ecological patterns of rhizosphere microbial communities is critical for propelling sustainable agriculture and managing ecosystem functions by exploiting microorganisms. However, this knowledge is still unclear, especially under host-associated large-scale and regarding the comparison between bacteria and fungi. We examined community assembly processes and community characters including environmental thresholds and co-occurrence patterns across the cultivatable area of Panax notoginseng for bacteria and fungi. Both are vital members of the rhizosphere but differ considerably in their life history and dispersal potentiality. Edaphic factors drove the parallel variations of bacterial and fungal communities. Although bacterial and fungal communities exhibited similar biogeographic patterns, the assembly of fungi was more driven by dispersal limitation than selection compared with bacteria. This finding supported the ‘size-dispersal’ hypothesis. pH and total nitrogen respectively mediated the relative importance of deterministic and stochastic processes in shaping bacterial and fungal communities. In addition, fungal communities exhibited potentially broader environmental thresholds and more modular co-occurrence patterns than bacteria (bacteria: 0.67; fungi: 0.78). These results emphasized the importance of dispersal limitation in structuring rhizosphere microbiota and shaping community features of ecologically distinct microorganisms. This study provides insights into the improved prediction and management of the key functions of rhizosphere microbiota.

Highlights

Plant and associated microbes are widely known as holobionts (Bordenstein and Theis, 2015); rhizosphere microbial communities play crucial roles in growth, health, and evolution of their host plant, as well as the biogeochemical cycling (Brunel et al, 2020)
These results suggested that similar environmental variables might drive the covariation of the α-diversities of bacterial and fungal communities
Previous studies showed that climatic factors are the best predictors of fungal community composition across a large space (Tedersoo et al, 2014; Zhang et al, 2020), possibly because the climatic gradients in our study area are much narrower than those in areas of continental or global scale

Summary

Introduction

Plant and associated microbes are widely known as holobionts (Bordenstein and Theis, 2015); rhizosphere microbial communities play crucial roles in growth, health, and evolution of their host plant, as well as the biogeochemical cycling (Brunel et al, 2020). Extensive studies have revealed that various factors drove the dynamics of rhizosphere microbial community, such as root exudates, edaphic factors, host genotype, and growth stage (Sasse et al, 2018; Zhang et al, 2018e). The macroecological patterns and community features, such as environmental responses and co-occurrence patterns of rhizosphere microbial communities at large spatial scale, especially with regard to the comparison between bacteria and fungi, are still poorly understood (Brunel et al, 2020) These patterns and features are essential to fully appreciate the formation of plant-microbe holobionts and to promote sustainable agriculture by manipulating microbes (Dini-Andreote and Raaijmakers, 2018)

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