青稞苗期根腐病对根际土壤细菌群落结构的影响

Effects of root rot disease at seedling stage on bacte⁃ rial community structure in the rhizosphere soil of naked barley

摘要:

【目的】明确青稞根腐病对根际土壤微生物细菌群落结构的影响。【方法】采集苗期健康青稞及根腐病发病率分别为 5%、10%、15%、20% 等不同发病率青稞根际土壤样品，采用 Illumina MiSeq 高通量测序技术测定各样品 16S rDNA 序列，并进行多样性分析。【结果】苗期青稞根际土壤细菌优势种属多，群落结构组成丰富，多样性及均匀性程度高。对不同分类水平下优势菌群分析发现，门水平下， 根腐病的发生使变形菌门（Proteobacteria）和拟杆菌门（Bacteroidetes）的丰度升高，使酸杆菌门（Acido- bacteria）和放线菌门（Actinobacteria）丰度降低 ；目水平下 ，微球菌目（Micrococcales）、假单胞菌目 （Pseudomonadales）和丙酸杆菌目（Propionibacteriales）的丰度降低，芽孢杆菌目（Bacillales）和鞘脂单胞菌目（Sphingomonadales）的丰度升高；属水平下，鞘脂单胞菌属（Sphingomonas）、芽孢杆菌属（Bacil- lus）、假单胞菌属（Pseudomonas）和不动杆菌属（Acinetobacter）的丰度升高，Pseudarthrobacter 属丰度降低；种水平下，普城沙雷菌（Serratia plymuthica）丰度增加，简单芽孢杆菌（Bacillus simple）、醋酸钙不动杆菌（Acinetobacter calcoaceticus）及嗜根寡养单胞菌（Stenotrophomonas rhizophila）的丰度降低。聚类分析发现，根腐病的发生使青稞根际土壤细菌群落结构发生了变化，且总体呈现出发病率越高，与健康样品的距离越远，差异越大的规律。通过 COG 数据库注释得到青稞根际土壤细菌多个功能基因。 【结论】青稞苗期根腐病的发生使根际土壤细菌群落结构发生了变化，这一研究为青稞根腐病的防控及预测预警技术的建立提供了理论依据。

关键词:青稞;根腐病;高通量测序;土壤细菌;群落结构

Abstract:

【Objective】The aim of this study was to investigate the effects of naked barley root rot disease on the bacterial community structure of rhizosphere soil.【Method】 The rhizosphere soil samples of healthy naked barley at seedling stage were collected with 5%，10%，15% and 20% incidence of root rot，and then the 16S rDNA gene of ev- ery sample was determined by Illumina MiSeq high-throughput sequencing technology.Furthermore，the diversity of rhizosphere bacterial species was analyzed.【Result】 The results illustrated that there were many dominant bacterial species in the rhizosphere soil of naked barley in the seedling stage，and the community structure was rich with high di- versity and uniformity.Futher more，through the analysis of the dominant bacteria at different classification levels ，dif- ferent rules were revealed.Firstly，at the phylum level，the occurrence of root rot increased the abundance of Proteo- bacteria and Bacteroidetes，while the abundance of Acidobacteria and Actinobacteria decreased.Secondly，at the ob- jective level，the occurrence of root rot reduced the abundance of Micrococcales，Pseudomonadales and Propionibacte- riales，but the abundance of Bacillales and Sphingomonadales increased.Thirdly，at the level of genus，the abundance of Sphingomonas，Bacillus，Pseudomonas and Acinetobacter raised，whereas the abundance of Pseudarthrobacter dropped down.Finally，at the species level，the abundance of Serratia plymuthica had grown much as the incidence in- creased.However，there was an opposite trend on the abundance of Bacillus Simple，Acinetobacter calcoaceticus and Stenotrophomonas rhizophila.Cluster analysis showed that the occurrence of root rot caused changes in the structure of the rhizosphere soil bacterial community of naked barley，and the overall law showed that the higher the incidence， the farther the distance from the healthy samples，the greater the difference.Besides，several functional genes of naked barley rhizosphere soil bacteria were obtained by COG database annotation.【Conclusion】 Therefore，it’s obviously that the occurrence of naked barley root rot at seedling stage changed the bacterial community structure in the rhizo- sphere soil.This study provides theoretical basis for the prevention and control of naked barley root rot and the estab- lishment of prediction and early warning technology.

Key words:naked barley;root rot;high-throughput sequencing; soil bacteria; community structure