Microbial community analysis of apple rhizosphere around Bohai Gulf

Jihang Jiang,Hui Guo,Xiaotong Yang,Zhen Song,Zhiquan Mao,Xiaohong Nie,Xiawei Peng

doi:10.1038/s41598-017-08398-9

Jihang Jiang, Hui Guo + Show 5 more

Open Access

https://doi.org/10.1038/s41598-017-08398-9

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Abstract

Bohai Gulf is the main area for apple tree cultivation in China. Consecutive replanting significantly affects the yield and quality of apple trees in this area. Microecological imbalance in apple trees’ rhizospheres caused by variation in the soil microbial community is considered the primary cause of apple replant disease (ARD). This study analysed the microbial communities of the rhizospheres of perennial apple trees (PAT) and apple tree saplings under replanting (ATS) around Bohai Gulf using high-throughput sequencing. The results revealed increased populations of typical pathogenic fungi Verticillium and bacteria Xanthomonadaceae, and decreased populations of beneficial bacterial populations Pseudomonas and Bacillus with replanting, suggesting that competition between pathogens and beneficial microbes varies according to the ratio of pathogens to beneficial microbes in rhizosphere soil under the replanting system. Meanwhile, replanting was accompanied by an increase in the antagonistic bacteria Arthrobacter and fungus Chaetomium, suggesting that increased numbers of pathogens can lead to more instances of antagonism. Redundancy analysis (RDA) revealed site position and the main soil properties (pH, organic matter, available N, available K, available P, and moisture) affected the microbial community composition. It found clear differences in soil microbial communities and demonstrated a better understanding of the causes for ARD.

Highlights

Apple replant disease (ARD) is common in all major apple growing areas in the world
A total of 623,094 raw bacterial reads and 524,083 raw fungal reads were obtained from the rhizosphere of perennial apple tree (PAT) and apple tree saplings under replanting (ATS) soils
The present study determined that different biocontrol microbes have different resistance mechanisms, and that some are affected by a single mechanism while others are affected by a variety of mechanisms. These findings suggest that with continued heavy apple cultivation, soil microbial communities may be transformed from a biological system suitable for apple tree growth to a biological system that promotes apple replant disease (ARD)

Summary

Introduction

Apple replant disease (ARD) is common in all major apple growing areas in the world. ARD has been linked to a substantial decrease in both yield and quality of apples in most apple growing regions, with economic losses equivalent to as much as 50% of production throughout the lifetime of the apple orchard[1]. Our research compared the microbial community’s composition and structure by examining the presence of bacteria and fungi in perennial apple tree (PAT) and apple tree saplings under replanting (ATS) soils of Bohai Gulf to monitor variations after replanting. This was done to provide a basis for reasonable understanding of the rhizosphere microbial community’s role in overcoming ARD

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