Contrasting Responses of Rhizosphere Bacteria, Fungi and Arbuscular Mycorrhizal Fungi Along an Elevational Gradient in a Temperate Montane Forest of China

Abstract

Elevational gradients strongly affect microbial biodiversity in bulk soil through altering plant and soil properties, but the effects on rhizosphere microbial patterns remain unclear, especially at large spatial scales. We therefore designed an elevational gradient experiment to examine rhizosphere microbial (bacteria, fungi and arbuscular mycorrhizal fungi) diversity and composition using Illumina sequencing of the 16S rRNA and ITS genes for comparison to plant and soil properties. Our results showed that bacterial and fungal alpha diversity was significantly higher at mid-elevation, while AMF alpha diversity decreased monotonically. The beta diversities of the three groups were significantly affected by elevational gradients, but the effect on bacterial beta diversity was larger than on fungal and AMF beta diversity. Proteobacteria, the dominant phyla of bacteria, was significantly higher at the mid-elevation, while Acidobacteria and Actinobacteria significantly decreased as elevation increased. The main fungal taxa, Basidiomycota, significantly decreased with elevation, and Ascomycota significantly increased with elevation. Glomeromycota, the dominant AMF phyla, responded insignificantly to the elevational gradients. The responses of bacterial and fungal alpha diversity were mostly associated with tree diversity and organic carbon, whereas AMF alpha diversity mainly depended on litter N and P. Changes in bacterial community composition along the elevational gradient were explained primarily by litter N and P, and litter P was the main driver of fungal and AMF community composition. Overall, our results suggest that plant litter, particularly litter N and P, were the main source of external carbon input and drove the observed differences in rhizosphere microbial diversity and community composition. Our results highlight the importance of litter nutrition in structuring rhizosphere microbial communities in mountain ecosystems.

Comparative Analyses of Rhizosphere Bacteria Along an Elevational Gradient of Thuja sutchuenensis

“…Due to geographic separation, soil bacterial communities tend to display population stratification, such as elevational gradients, vertical depth, and horizontal distances. Among them, elevational gradients distinctively alter soils’ bacterial composition and diversity by affecting plant and soil properties compared with fine-scale spatial variations ( Guo et al, 2020 ). In the present study, the LDA results showed that the dominant bacterial indicators for rhizosphere were Variibacter , Rhodomicrobium , and Rhizobium from Proteobacteria.…”

“…As a micro-environment of plant roots, the rhizosphere is an important site for soil-root-microorganism interaction ( Biddle et al, 2008 ; Bryant et al, 2008 ). Rhizosphere microorganisms are composed of many beneficial bacteria, playing profound roles in promoting plant growth and development ( Guo et al, 2020 ). Purposeful conservation of microbial communities is important for the survival and expansion of endangered plants.…”

Contrasting patterns and co-occurrence network of soil bacterial and fungal community along depth profiles in cold temperate montane forests of China

“…Previous studies of microbial diversity in mountain ecosystems reported different altitude-diversity patterns (Shen et al, 2013; Shen et al, 2014; Singh et al, 2014; Peay et al, 2017; Ren et al, 2018; Guo et al, 2020; Shen et al, 2020). Similar to the results of most studies based on high-throughput sequencing technology (Li et al, 2018; Shen et al, 2015; Shen et al, 2019), we found that soil bacterial diversity decreased with increasing altitude, however, the fungal diversity increased with altitude, which partially supported our first hypothesis.…”

Different patterns of belowground fungal diversity along altitudinal gradients with respect to microhabitat and guild types

“…However, only a few studies on the changes in fungal community composition along altitudinal gradients have been reported. Intriguingly, the altitudinal patterns of alpha diversity showed inconsistent or non-signi cant patterns [28][29][30][31][32].…”