Dynamics of Bacterial Community Structure in the Rhizosphere and Root Nodule of Soybean: Impacts of Growth Stages and Varieties.

Soo-In Sohn,Eun-Kyoung Shin,Kong-Sik Shin,Young-Ju Oh,Hyeon-Jung Kang,Woo-Suk Cho,Subramani Pandian,Jae-Hyung Ahn,Youn-Sung Cho

doi:10.3390/ijms22115577

Abstract

Bacterial communities in rhizosphere and root nodules have significant contributions to the growth and productivity of the soybean (Glycine max (L.) Merr.). In this report, we analyzed the physiological properties and dynamics of bacterial community structure in rhizosphere and root nodules at different growth stages using BioLog EcoPlate and high-throughput sequencing technology, respectively. The BioLog assay found that the metabolic capability of rhizosphere is in increasing trend in the growth of soybeans as compared to the bulk soil. As a result of the Illumina sequencing analysis, the microbial community structure of rhizosphere and root nodules was found to be influenced by the variety and growth stage of the soybean. At the phylum level, Actinobacteria were the most abundant in rhizosphere at all growth stages, followed by Alphaproteobacteria and Acidobacteria, and the phylum Bacteroidetes showed the greatest change. But, in the root nodules Alphaproteobacteria were dominant. The results of the OTU analysis exhibited the dominance of Bradyrhizobium during the entire stage of growth, but the ratio of non-rhizobial bacteria showed an increasing trend as the soybean growth progressed. These findings revealed that bacterial community in the rhizosphere and root nodules changed according to both the variety and growth stages of soybean in the field.

Highlights

Introduction300 million tons per year [1]
Soybeans (Glycine max (L.) Merr.) are one of the world’s most valuable crops, yielding300 million tons per year [1]
We examined the interactions between soybeans and microorganisms, soybeans and root nodule bacteria, and rhizosphere and root nodule bacteria in the field environment

Summary

Introduction

300 million tons per year [1]. It was first cultivated in China and spread to other parts of the globe [2]. The global soybean cultivation area is 128.22 million ha, up 1.9 percent year on year [3]. The use of chemical fertilizers result in environmental perturbations like eutrophication in rivers and lakes as well as global warming. We must consider the environmental issues along with the yield for the sustainable agricultural production. The effective use of rhizosphere microorganisms for the desirable growth of soybeans is necessary for sustainable agricultural production. Biofertilizers containing specific strains of plant growth-promoting rhizobacteria (PGPR) have been used for decades to increase plant nutrient use efficiency and reduce the use of chemical fertilizers and pesticides [4]. Applied biofertilizer interacts with rhizosphere and root-associated microbes and later successfully colonize the roots to benefit the plant [5,6,7,8,9]

Methods

Results

Conclusion