摘要
【目的】采用18S r DNA PCR-DGGE技术研究苦楝-小麦农林复合生态系统根际及非根际土壤真菌群落结构,以期揭示农林复合生态系统中伴生树种对作物根际真菌群落的影响,为农林复合经营实践提供理论参考。【方法】提取根际和非根际土壤真菌DNA,采用通用引物GC-FR1和FF390扩增18S r DNA基因目的片段,扩增片段用变性梯度凝胶电泳分析;不同处理间微生物群落结构的相似性采用非加权组算术平均法分析比较;以物种丰富度指数、Shannon-Wiener多样性指数和均匀度指数3个指标评价各样品真菌多样性;最后将DGGE图谱中的优势条带割胶测序并建立系统发育树。【结果】根际真菌群落结构和多样性远比非根际土壤复杂,且根际土壤样品DGGE电泳图谱中优势条带数也比非根际土壤样品多。进一步采用非加权组算术平均法对不同处理间真菌群落结构的相似性进行分析,发现每个处理组3次重复间的相似度除苦楝根际土壤外均大于70%;在聚类分析图中所有处理明显分为3个组,相似度为51%;小麦根际真菌菌群与苦楝-小麦农林复合系统中的小麦根际真菌相似性最高,相似度为72%,表明苦楝对小麦根际真菌群落的影响不大;苦楝根际真菌菌群与其他各组间差异较大,相似度仅为51%。主成分分析结果也表明所有处理明显分为3个群组。多样性分析结果表明,各处理组根际真菌之间以及非根际真菌间丰富度差异均不明显,而苦楝-小麦农林复合系统中的小麦及苦楝根际真菌丰富度显著高于非根际真菌;根际真菌的Shannon-Wiener多样性指数存在显著差异,非根际真菌的Shannon-Wiener多样性指数差异不显著;根际真菌及非根际真菌各组间均匀度指数差异不大,而小麦-苦楝农林复合系统中的小麦以及苦楝根际真菌与非根际真菌均匀度指数存在明显差异。此外,DGGE图谱中的11条优势条带克隆测序结果表明,3条条带为不能培养的真菌,其余8条条带对应的同源性最高的序列分别属于球囊菌门、担子菌门、子囊菌门和半知菌亚门。【结论】小麦-苦楝农林复合系统中的小麦根际真菌丰富度、多样性指数和均匀度均比单纯小麦根际真菌高,表明此复合系统中伴生的苦楝可增加小麦根际真菌的多样性。
【Objective 】 To explore the influence of tree species on rhizosphere-associated fungal community in an agroforestry ecosystem, and to provide new insights into agroforestry practice, the fungal community structure in rhizosphere and bulk soil in Melia azedarach-Triticum aestivum agroforestry ecosystem was investigated by 18 S rDNA PCRDGGE.【Method】After the fungal DNA was extracted from extraction of nonrhizosphere and rhizosphere-associated soil,and the targeted fungal 18 S rDNA was amplified using universal primers GC-FR1 and FF390. And then the amplified DNA fragments were analyzed by density gradient gel electrophoresis（ DGGE）. Similarity among different groups was analyzed using the UPGMA（ unweighted pair group method with arithmetic averages） method,and the fungal diversity was evaluated with species richness（ S）,Shannon-Wiener index（ H） and the equitability index（ E）. Finally,dominant DGGE bands were excised,sequenced and a phylogenetic tree was constructed. 【Result 】 Results showed that thestructure and diversity of rhizosphere-associated fungi community were much more complex than that of the bulk soil,and more dominant bands were observed in DGGE profiles of rhizosphere soil samples. The DGGE profiles were further investigated by cluster analysis using the UPGAMA method,revealing that the similarity among the three replicates of each treatment was more than 70% except for the rhizosphere soil of M. azedarach. In clustering diagram,all the samples were grouped into three clusters with a similarity of 51%. The highest similarity（ 72%） was found between the rhizosphereassociated fungal community from wheat and wheat grown under M. azedarach,which indicated that M. azedarach had minor influence on the rhizosphere-associated fungal community of wheat. In addition,only 51% similarity was noticed between the rhizosphere-associated fungal community of M. azedarach and the other groups. The principal-component analysis（ PCA） also demonstrated that all the treatments was divided into three groups. There were no obvious differences in species richness among rhizosphere-associated fungal communities and nonrhizosphere fungal communities. However,the species richness of rhizosphere-associated fungal community from wheat grown under M. azedarach and M. azedarach were higher than nonrhizosphere fungal community. There were significant differences in Shannon-Wiener indexes among rhizosphere-associated fungal communities, while the difference was not significant among nonrhizosphere fungal communities. Additionally,no significant differences were present in equitability index among rhizosphere-associated fungal communities or nonrhizosphere fungal communities,whereas,the equitability index between rhizosphere-associated and nonrhizosphere fungal community of wheat grown under M. azedarach was significantly different,and the same as M.azedarach. Finally,sequencing of eleven dominant DGGE bands showed that 3 of the 11 sequences were uncultured fungi and the rest 8 sequences belonged to Glomeromycota,Basidiomycota,Ascomycota or Deuteromycota. 【Conclusion】The species richness,Shannon-Wiener index and equitability index of rhizosphere-associated fungi from wheat grown under M.azedarach were higher than that of monocultured wheat,which indicated that diversity of rhizosphere-associated fungal community of wheat was enriched by trees grown in this agroforestry ecosystem. Our results may provide new reference for agroforestry practice.
出处
《林业科学》
EI
CAS
CSCD
北大核心
2015年第10期26-34,共9页
Scientia Silvae Sinicae
基金
林业公益性行业科研专项"江苏沿海困难立地造林关键技术研究"(201304211)
