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

Yaoxin Guo; Chengjie Ren; Junjie Yi; Russell Doughty; Fazhu Zhao

doi:10.3389/fmicb.2020.02042

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

Front Microbiol. 2020 Aug 20:11:2042. doi: 10.3389/fmicb.2020.02042. eCollection 2020.

Authors

Yaoxin Guo¹, Chengjie Ren², Junjie Yi¹, Russell Doughty³, Fazhu Zhao⁴

Affiliations

¹ Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), Northwest University, Xi'an, China.
² College of Agronomy, Northwest A&F University, Yangling, China.
³ Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK, United States.
⁴ College of Urban and Environmental Sciences, Northwest University, Xi'an, 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.

Keywords: elevational gradients; microbial community; plant properties; rhizosphere soil; soil properties.