铝胁迫对酸性红壤中真菌种群多样性的影响

Effect of Aluminum Stress on Fungal Community Diversity in Acidic Red Soils

通过聚合酶链式反应-限制性片段长度多态（PCR-RFLP）技术构建了红壤真菌的内转录间隔区（Internal Transcribed Spacer,ITS）rDNAs文库,比较分析了红壤地区典型森林土和农田土真菌群落结构对铝胁迫的响应,构建了6个土壤样品的真菌ITS rDNAs文库。从这6个克隆文库中随机挑取克隆进行了PCR-RFLP指纹图谱分析,共获得77个独特的真菌操作分类单元（OperationalTaxanomicalUints,OTUs）。对77个OTUs的代表性克隆测序并利用Blast工具进行分析（相似性95%～100%）。研究结果表明森林土壤和农田土壤样品中真菌类群79.2%（61）属于子囊菌门（Ascomycota）、担子菌门（Basidiomycota）和球囊菌门（Glomeromycota）,20.8%（16）属于未分类的簇（Unclassifiedfungi）,其中担子菌门真菌在两种土壤中具有明显优势。物种多样性指数（Simpson、Shannon和Chao1）分析表明,铝胁迫降低了土壤真菌种群的多样性,农田土壤中真菌的种群多样性明显高于森林土壤。而且随着铝胁迫浓度的增加,担子菌门真菌在两种土壤中丰度明显下降,子囊菌门真菌的丰度显著上升,在高铝处理浓度处理的土壤中演变为优势种群。

Aluminum（Al）in acidic soils shows toxicity to soil microbes. In this study, we constructed fungal internal transcribed spacer（ITS）rDNAs clone library using the PCR-amplified restriction fragment length polymorphism（PCR-RFLP）method, and comparatively studied the responses of fungal community in forest soil and agriculture soil to Al stress. A total of six fungal clone communities was obtained from the tested soil samples. Clones of each library were randomly selected for PCR-RFLP analysis of ITS rDNA fragments. Totally 77 genotypes were identified by RFLP fingerprinting and sequenced. These 77 genotypes were then sequenced and their respective phylotypes were identified through the Basic Local Alignment Search Tool（BLAST）of the National Center for Biotechnology Information（NCBI）with similarity of 95%～100%. Sequence results revealed that 79.2%（61）of the clone sequences have the highest similarity with those of the Ascomycota, Basidiomycota and Glomeromycota, and 20.8%（16）have near similarity with unclassified fungi. Basidiomycota was predominant in both soils. The Simpson, Shannon and Chao1 indices all showed that Al addition reduced the richness and diversity of soil fungi. However, the diversity of fungal communities was lower in the forest soil than in the agriculture soil. Elevated Al increased the relative abundance of Ascomycota but decreased that of Basidiomycota, thus evolving into dominant population in high Al soils.