Variations of Bacterial Community Diversity Within the Rhizosphere of Three Phylogenetically Related Perennial Shrub Plant Species Across Environmental Gradients

Abstract

Rhizosphere microbial communities are of great importance to mediate global biogeochemical cycles, plant growth, and fitness. Yet, the processes that drive their assembly remain unclear. The perennial shrubs Caragana spp., which is well known for their role in soil and water conservation, provides an ideal system to study the biogeography of rhizosphere microorganism communities within natural ecosystems. In order to detect how bacterial rhizosphere communities vary in terms of community diversity and composition, the rhizosphere bacterial community of three Caragana species, Caragana microphylla Lam., C. liouana Zhao, and C. korshinskii Kom., which distributed in arid and semi-arid region of northern China were investigated. Across species, Proteobacteria (61.1%), Actinobacteria (16.0%), Firmicutes (8.6%), Bacteroidetes (3.0%), Acidobacteria (3.5%), Gemmatimonadetes (1.4%), and Cyanobacteria (1.0%) were the most dominant phyla in the rhizosphere of the three Caragana species. The relative abundance of Cyanobacteria was significantly higher in rhizosphere of C. korshinskii Kom. compared with C. microphylla Lam. and C. liouana Zhao, while the opposite was found for Gemmatimonadetes in rhizosphere of C. microphylla Lam. relative to C. liouana Zhao. Stepwise multiple linear regression analysis showed that both diversity and richness of the bacterial rhizosphere communities significantly and positively correlated with soil pH (p < 0.01). Distance-based redundancy analysis indicated that soil properties and non-soil parameters detected there accounted for 47.5% of bacterial phylogenetic structure variation (p < 0.01) all together. Meanwhile, soil total phosphorus accounted for the greatest proportion of community structure variance (9.7%, p < 0.01), followed by electrical conduction (6.5%), altitude (5.8%), soil pH (5.4%), mean annual precipitation (3.6%) and total nitrogen (3.6%, p < 0.05 in all cases). Furthermore, partial Mantel test suggested that bacterial rhizosphere community structure significantly correlated with geographical distance, indicating that the less geographical distant sample sites tend to harbor more similar bacterial rhizosphere community. Our results shed new light on the mechanisms of coevolution and interaction between long-lived plants and their rhizosphere bacterial communities across environmental gradients.

Microbiome Dynamics Associated With the Atacama Flowering Desert

“…These findings reflect the sensibility of soil fungi to changing climatic and edaphic conditions (Tedersoo et al, 2014). In contrast, rhizospheric bacterial communities had 44% of the OTUs in common, in disagreement other studies, which state that geographical distances reduce the similarity of bacterial communities (Martiny et al, 2011;Wang et al, 2017;Na et al, 2018). However, our results agree with those of Van der Walt et al (2016) from the Namib Desert, suggesting that there may be "similar underlying drivers" for microbial distribution in both west coast deserts.…”

“…A cause for the minor size of the core microbiome are probably the divergent habitat conditions (soil physicochemical and environmental factors) along the latitudinal gradient (Nuccio et al, 2016;Na et al, 2018).…”

“…(3) plant species, where the relative abundance of certain microbial taxa depends on their host-specificity (Fonseca-García et al, 2016); and (4) soil physico-chemical properties (Coleman et al, 2016;Na et al, 2018). Jorquera et al (2016) reported that microbial communities in the rhizosphere of perennial Atacama Desert plants vary according to both environment and plant.…”

Drivers of the composition of active rhizosphere bacterial communities in temperate grasslands

“…Black circles reflect means for all pairwise comparisons within each of the eight soil types, for all combinations of two out of eight soil types (n = 28), within the six plant species, and for all combinations of two out of six plant species (n = 15) p values were determined through t-tests the developmental stage and physiological status of the host plant and thereby the composition of root exudates. Alternatively, specific soil physicochemical conditions may directly select for particular bacterial species in the rhizosphere [39]. When the quantitative contribution of all variables covered by the present study (Tables S2 and S3) to differences in the rhizobiome composition was assessed by variance partitioning, soil characteristics alone were found to explain most of the variance (30%).…”

Desert Microbes for Boosting Sustainable Agriculture in Extreme Environments

“…In an effort to inspect the factors influencing rhizosphere bacterial community, Na et al (2018) investigated the rhizosphere bacterial community of the widely distributed perennial shrub Caragana in the arid and semi-arid areas of north China. The authors revealed the bacterial communities dominating the rhizosphere across three Caragana species belonged to Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Acidobacteria, Gemmatimonadetes, and Cyanobacteria, while on the genus level Pseudomonas, Acinetobacter, Bacillus, Stenotrophomonas, Burkholderia, Paenibacillus, Sphingobacterium, Chitinophaga, Arthrobacter, and Chryseobacterium were the most dominant genera.…”