青海不同区域农田作物土壤细菌多样性及群落结构分析

Comparison of soil bacterial diversity and community structure in different regions of Qinghai Province

摘要:

【目的】探讨青海省农田土壤细菌多样性及群落结构组成。【方法】采用高通量测序技术分析都兰县、互助县、共和县和大通县种植小麦、油菜、青稞土壤细菌群落结构组成及多样性差异，并解析其与土壤理化特性的关系。【结果】4个地区的土壤pH、水分、有机质、Chao1指数、Shannon指数、线性判别分析效应大小(linear discriminant analysis effect size, LEfSe)组间差异这些指标中部分指标存在极显著差异性(P<0.01)，而3种作物的这些指标无显著差异(P>0.05)。主成分分析(principal component analysis, PCA)显示，不同区域细菌群落组成差异性较大，3种作物农田土壤细菌群落、物种组成相似度较高。4个地区共有3 127个可操作性分类单元(operational taxonomic units, OTUs)，3种作物农田土壤细菌共有OTUs为3 694个；细菌物种隶属于36门93纲192目276科450属423种；4个地区或3种作物土壤具有相似的优势门、属、种，但相对丰度不同。水分、pH、有机质与Chao1、Shannon存在显著相关性，pH、有机质与未分类种、unclassified RB41、unclassified Sphingomonas具有显著正相关或负相关。Chao1、Shannon与unclassified Sphingomonas显著负相关，与unclassified RB41、unclassified Vicinamibacteraceae显著正相关。【结论】区域差异对土壤的理化性质、细菌群落结构和多样性具有显著影响，相较于作物而言其影响更加明显。

Abstract:

[Objective] To investigate the diversity and community structure of soil bacteria in the farmlands in Qinghai Province. [Methods] High-throughput sequencing was employed to analyze the bacterial community structure and diversity in the soil samples of farmlands growing wheat, oilseed rape, and highland barley in Dulan, Huzhu, Gonghe, and Datong counties. Furthermore, the relationship between bacterial community structure and soil physicochemical properties was analyzed. [Results] The pH, moisture, and organic matter of soil, as well as the Chao1 and Shannon indexes and linear discriminant analysis effect size (LEfSe) of soil bacteria, showed significant differences in some of these indexes (P<0.01) but no significant differences among the three crops (P>0.05). The results of principal component analysis (PCA) showed that the bacterial community structure was different among different regions but highly similar in the farmlands of the three crops. A total of 3 127 operational taxonomic units (OTUs) and 3 694 OTUs were common in the four regions and in the farmlands of the three crops, respectively. The OTUs of soil bacteria were identified as 423 species, 450 genera, 276 families, 192 orders, 93 classes of 36 phyla. The four regions or three crops had similar dominant phyla, genera, and species, while these taxa differed in relative abundance. Soil moisture, pH, and organic matter were significantly correlated with Chao1 and Shannon indexes. Soil pH and organic matter had significantly positive or negative correlations with unclassified species, unclassified RB41, and unclassified Sphingomonas. Chao1 and Shannon indexes had significantly negative correlations with unclassified Sphingomonas but positive correlations with unclassified RB41 and unclassified Vicinamibacteraceae. [Conclusion] Regional differences had significant effects on soil physicochemical properties, bacterial community structure and diversity, which were more obvious than those of crop differences.