连作和感病对烟株根际土壤真菌群落结构的影响

Effects of continuous cropping and infection on fungal community structure in tobacco-planting rhizosphere soil

【目的】了解连作及其与根腐病感染对烟株根际土壤真菌群落结构及多样性的影响,为连作土壤微生态环境定向调控和根腐病精准防治提供理论依据和技术指导。【方法】分别选取连作2,4和8年烟田健株(依次记为HT2、HT4、HT8)和根腐病感病烟株(依次记为ST2、ST4、ST8)根际土壤,以同区域撂荒2年以上耕层土壤为对照(CK),测定不同处理土壤理化性质,利用高通量测序技术分析不同连作年限烟田健株和病株根际土壤真菌群落组成和多样性的差异,并基于冗余分析探讨了土壤化学性质与真菌群落分布的相关性。【结果】与对照(CK)相比,连作和感病降低了烟株根际土壤真菌群落的丰富度和多样性。健株根际土壤真菌优势菌群累积相对丰度总和小于病株。属水平上,连作2年和4年烟田健株和病株根际土壤镰刀菌属(Fusarium)相对丰度增幅为81.3%~665.1%,随连作年限的延长,健株和病株根际土壤淡紫紫孢菌属(Purpureocillium)相对丰度降幅为295.2%~1387.1%;种水平上,健株和病株根际土壤茄腐镰刀菌(Fusarium solani)相对丰度增幅为88.5%~844.3%。土壤指示物种相对丰度随连作年限的延长而降低。土壤化学性质与真菌群落丰度密切关联,其中pH值和速效钾含量是影响连作和感病烟株根际土壤真菌群落分布的核心环境因子。【结论】连作和感病降低了烟株根际土壤真菌群落及有益菌群落的丰富度和多样性,但提高了病原菌的相对丰度,茄腐镰刀菌可能是引起试验烟株根腐病的主要病原菌。

【Objective】This study investigated the effects of continuous cropping and interaction between continuous cropping and root rot infection on the structure and diversity of soil fungal in the rhizosphere of tobacco plants to provide basis and guidance for the directional control of soil micro-ecological environment and precise control of root rot diseases.【Method】Rhizosphere soil samples were collected from continuous cropping plants at the ages of 2,4 and 8 years(recorded as HT2,HT4 and HT8)and root rot susceptible tobacco plants(recorded as ST2,ST4 and ST8),respectively.Soil in the same area abandoned for more than 2 years was used as control(CK).Soil physicochemical properties of different treatments were determined.High-throughput sequencing technology was used to analyze the differences in the rhizosphere soil fungal community composition and diversity and correlation between soil chemical properties and fungal community distribution.【Result】Compared with CK,continuous cropping and susceptibility reduced the fungal community richness and diversity in the rhizosphere soil of tobacco plants.Cumulative re-lative abundance of the dominant fungal flora in the rhizosphere soil of healthy plants was less than that of diseased plants.At the genus level,the relative abundance of Fusarium in the rhizosphere soil of healthy and diseased plants in tobacco fields was increased by 81.3%to 665.1%for 2 and 4 years of continuous cropping,while Purpureocillium was decreased by 295.2%to 1387.1%.At the species level,the relative abundance of Fusarium solani in the rhizosphere soil of healthy and diseased plants was increased by 88.5%to 844.3%.The relative abundance of soil indicator species decreased with the increase of continuous cropping years.Soil chemical properties were closely related to fungal community abundance,among which pH value and available potassium content were the key environmental factors affecting the distribution of fungal community in the rhizosphere soil of continuous cropping and susceptible tobacco plants.【Conclusion】Continuous cropping and diseased-susceptibility reduced the richness and diversity of soil fungal community and beneficial bacterial community in the rhizosphere soil of tobacco plants,but increased the relative abundance of pathogenic bacteria.F.solani maybe the main pathogen casing the root rot of experimental tobacco plants.