烟草根黑腐病不同发病程度与土壤养分及微生物群落的关系

【目的】分析烟草根黑腐病发病程度对土壤养分及微生物群落结构的影响,探究不同病害发生条件下土壤环境、微生物群落间的关系,为烟草根黑腐病防控提供理论依据。【方法】以贵州省安顺烟区为调查区域,收集烟草根黑腐病不同发病程度(0、1、3、5级)烟株根际土壤,测定土壤理化性质;采用16S rDNA和ITS基因测序技术进行分析,探讨不同发病程度下烟株根际土壤养分、细菌及真菌群落结构差异。【结果】与正常土壤相比,随着病害程度的加重,土壤细菌群落的均匀度和丰富度降低,而真菌群落的均匀度和丰富度升高。与正常土壤相比,发病土壤中细菌群落鞘氨醇单胞菌属(Sphingomonas)、Candidatus_Udaeobacter、苔藓杆菌属(Bryobacter)和芽单胞菌属(Gemmatimonas)相对丰度下降,而芽孢杆菌(Bacillus)丰度上升;同时真菌群落镰刀菌属(Fusarium)、柱孢属(Cylindrocarpon)、毛霉属(Mucor)丰度下降,而Nicotiana、茎点霉属(Setophorna)、亡革菌属(Thanatephorus)、锥毛壳属(Coniochaeta)、织球壳菌属(Plectosphaerella)和四枝孢属(Tetracladium)丰度上升。指示物种分析结果表明,芽单胞菌属、织球壳菌属和四枝孢属可能是不同发病程度土壤细菌、真菌群落属水平差异的主要物种。冗余分析(RDA)和方差分解分析(VPA)结果表明,土壤铵态氮(NH-N)和有机质(SOM)是细菌、真菌群落结构发生变化的主要驱动因子。【结论】根际土壤中细菌芽单胞菌属丰度的下降和真菌四枝孢属丰度的上升是烟草根黑腐病严重发生的关键微生物因素,提高土壤SOM和NH-N含量能有效降低烟草根黑腐病发病程度。

Relationship between tobacco root black rot incidence degree and soil nutrients and microbial community

【Objective】To analyze effects of tobacco root black rot incidence degree on soil nutrients and microbial community structure,to explore relationship between soil environment and microbial community under different disease occurrence conditions,so as to provide a theoretical basis for prevention and control of black root rot.【Method】Tobaccogrowing area of Anshun,Guizhou was investigated. Rhizosphere soil of different incidence degrees of black rot(grade 0,1,3,5)was collected to determine physical and chemical property of the soil. 16S rDNA and ITS high-throughput sequencing technology were used for sequencing analysis to explore the differences in rhizosphere soil nutrients,bacterial and fungal community structure of tobacco plants under different disease degrees.【Result】Compared to normal soil,the severer the disease,the lower the evenness and richness of soil bacterial community and the higher the evenness and richness of soil fungal community. Compared with normal soil,relative abundance of bacterial communities Sphingomonas,Candidatus_Udaeobacter,Bryobacter,and Gemmatimonas in the pathogenic soil decreased;and abundance of Bacillus increased;abundance of fungal communities Fusarium,Cylindrocarpon,Mucor decreased and abundance of Nicotiana,Setophorna,Thanatephorus,Coniochaeta,Plectosphaerella,and Tetracladium increased. Analysis of the indicated species showed Gemmatimonas,Plectosphaerella,Tetracladium were the main different species in soil bacterial and fungal communities of difference incidence degrees at genus level.Resultsof redundancy analysis(RDA)and variance decomposition analysis(VPA)showed that soil ammonium nitrogen(NH-N)and soil organic matter(SOM)were the main driving factors for changes in bacterial and fungal community structure.【Conclusion】Abundance decrease of bacterial Gemmatimonas and abundance increase of fungal Tetracladium are the key microbial factors for the serious occurrence of black rot in tobacco root,and increasing soil SOM and NH-N content can effectively reduce the incidence of tobacco root black rot.