不同生境马铃薯根际土壤细菌多样性分析

近年来，随着国家对马铃薯产业重视程度的增加，生产的专业化和规模化程度越来越高，化肥农药用量不断加大，加之连作等种植模式，致使以疮痂病为代表的土传病害普遍发生且逐年加重，个别地块发病率达90%以上，给种植业者带来巨大的经济损失。目的] 为了探索马铃薯疮痂病发生与土壤环境的关系，分析区域性种植方式和施肥量对土壤细菌种群变化的影响，为实现土传病害有效防治提供借鉴。方法] 本文分别从1年连作土传病害轻的宁夏西吉（西北）、3年连作土传病害严重的河北沽源（华北）、5年轮作未发现土传病害的内蒙古海拉尔（东北）大田马铃薯根际采集土壤，利用高通量测序技术，比较了样品间细菌群落结构差异。结果] 3组样品共获得有效条带617558条，可分类操作单元（OTUs）3077个。各样品中变形菌门（Proteobacteria）数量最多，含量均在33%以上。与未发病土壤样品相比，土传病害发生严重的样品中细菌数量、物种数、细菌多样性、种类丰富度均有所降低，有害菌数量增加，益生菌数量减少。其中，放线菌（Actinobacteria）数量明显增多，变形菌（Proteobacteria）、绿弯菌（Chloroflexi）和酸杆菌（Acidobacteria）数量明显减少，组分及数量差异明显的细菌（尤其是放线菌门）大多与土壤全磷含量呈显著相关。结论] 过量施用化肥和常年连作改变了土壤细菌群落结构，生态环境恶化，导致土传性病害发生。其中，磷可能是影响土壤微生物群落结构变化最主要的肥料元素。

Comparison of bacterial diversity in rhizosphere soil of potato in different habitats

With increasing emphasis on potato production, the planting scale and professional degree of potato grow very fast in recent years in China. However, ever-increasing application intensity of chemical fertilizers and pesticides, together with succession cropping, leads to more and more serious soil-borne diseases representing by potato common scab. In some areas, the incidence of soil-borne diseases even reaches 90% causing huge economic loss to farmers. Objective] To monitor the changes of soil bacterial population due to different planting patterns and intensities of fertilization, analyze the relationship between occurrence of soil-borne diseases and change of soil-environment, provide theoretical basis for effectively controlling soil-borne diseases of potato. Methods] Soil rhizosphere samples were collected from three distinct potato fields continuously cropped for one-year in Xiji (Ningxia, northwest), three-year in Guyuan (Hebei, north) and five-year in Hailar (Inner Mongolia, northeast) with low, high and rare incidence, respectively, of soil borne diseases. Then, high-throughput sequencing technology was used to comparably analyze the bacterial community structure and diversity of these samples. Results] A total of 617558 effective reads and 3077 sortable operating units (OTUs) were obtained from the 3 groups of samples. Among them, the dominant component was Proteobacteria with a proportion over 33%. Compared with the soil samples from the field without occurrence of potato soil-borne diseases, the bacterial abundance and diversity decreased significantly in the soil samples from the field with high incidence of potato soil-borne diseases. Meanwhile, augmentation and reduction of the relative abundance of pathogenic and probiotic bacteria, respectively, also were observed. Specifically, we found the relative abundance of Actinobacteria increased on a large scale, whereas that of Proteobacteria, Chloroflexi and Acidobacteria decreased dramatically. Moreover, we found that composition changes and quantities of some bacteria (especially Actinomycetes) were closely related to the total phosphorus content of soil. Conclusion] Excessive application of chemical fertilizers and perennial continuous cropping affected the soil bacterial community and damaged soil ecological environment thus resulting in potato soil-borne diseases eventually. In addition, phosphorus content change may be one of the important factors that alter community structure of soil microbes.