十字花科作物根肿病对根际土壤微生物群落的影响

为探究根肿病对十字花科作物根际土壤微生物多样性的影响,以罹病大白菜和健康株根际土壤为研究对象,采用高通量测序技术对2组样本的细菌16S rDNA和真菌ITS基因进行序列测定,分析了样本间的微生物群落结构和组成差异,同时测定根际土壤理化性质,探讨根肿病、土壤微生物群落、土壤环境因子三者的相关性。研究表明:1)患病植株根际土壤pH和总磷、总钾、碱解氮、速效钾含量显著低于正常植株根际土,而交换性钙含量明显增加。2)根肿病的发生降低了根际土壤中细菌种群的丰富度和多样性程度,但对根际土壤中的真菌α-多样性无明显影响。3)变形菌门、拟杆菌门、放线菌门等是所测土壤样本的主要优势细菌种群,其中患病植株根际土壤中拟杆菌门丰度显著高于健康植株根际土壤,放线菌门丰度则显著降低(P0.05)。优势细菌纲为γ-变形菌纲、拟杆菌纲、α-变形菌纲、放线菌纲、酸杆菌纲等,2组土壤样本间多种优势细菌纲相对丰度差异显著。4)根际土壤优势真菌类群为子囊菌门、被孢霉门、担子菌门和壶菌门,其相对丰度在患病和健康株根际土壤样本中均有明显差异。主要真菌纲为散囊菌纲、被孢霉纲、锤舌菌纲等,并且土壤样本间的多种优势真菌纲相对丰度存在显著性差异。5)主坐标分析结果表明病株根际土壤与健康株根际土壤细菌和真菌群落结构差异明显,冗余分析结果显示速效钾和交换性钙是根际土壤微生物群落变化的主要影响因素。研究结果为揭示根肿病发生的根际微生态机制以及研发根肿病综合防控技术提供理论支撑。

Crucifer clubroot disease changes the microbial community structure of rhizosphere soil

To determine the effects of clubroot disease on microbial diversity of rhizosphere soils, the bacterial 16S rDNA region and fungal ITS region from the rhizosphere soils of clubroot-infected and healthy Chinese cabbage were sequenced and analyzed to evaluate the microbial community composition and structure. Moreover, we also measured the physiochemical properties of the two groups of soil samples, aiming to establish the relationship among clubroot occurrence, microbial community structures, and soil environmental factors. Soil pH and the contents of total phosphorus, total potassium, available nitrogen, and available phosphorus were significantly lower in the rhizosphere soil of clubroot-infected Chinese cabbage than those of healthy plants, whereas the exchangeable calcium content was increased in diseased soil. The occurrence of clubroot significantly reduced the richness and diversity of bacterial populations but had no significant effect on the fungal alpha-diversity in rhizosphere soils. The dominant bacterial phyla for the two groups of soil samples were Proteobacteria, Bacteroidetes, Actinobacteria, Acidobacteria, and Chloroflexi, of which Bacteroidetes had a higher abundance in the rhizosphere soil of clubroot-infected Chinese cabbage than that of healthy plants (P<0.05), whereas Actinobacteria had a lower abundance (P<0.05). At the class level, Gammaproteobacteria, Bacteroidia, Alphaproteobacteria, Actinobacteria, and Acidobacteria were the predominant bacterial communities, and the relative abundance of Bacteroidia, Actinobacteria, Oxyphotobacteria were significantly different between the two blocks (P<0.05). The dominant fungal phyla were Ascomycota, Mortierellomycota, Basidiomycota, and Chytridiomycota, whereas Eurotiomycetes, Mortierellomycetes, Leotiomycetes, Sordariomycetes, and Dothideomycetes were the predominant classes, and the relative abundance of these dominant phyla and classes were significantly different between Group 1 and 2 (P<0.05). Principal coordinates analysis (PCoA) showed that clubroot played an important role on the structure change of the soil microbial community, and distance-based redundancy analyses (db-RDA) indicated that soil available phosphorus and exchangeable calcium were the principal factors that correlated with the microbial community structure of rhizosphere soil. This research revealed micro-ecological changes of the rhizosphere with the occurrence of clubroot disease and provided theoretical support for developing a comprehensive control method of clubroot disease.