新疆长期连作棉花根际土壤微生物群落演替解析

Previous studie have found that there is strong consistency between the succession process of the soil microbial community in plough horizon with the widespread rule of continuous cropping obstacles led to the reduction of plant and the outbreaks of diseases and insect pests in Xinjiang province, in the process of long-term continuous cotton cropping. But, it has not been identified that the key microbial community composition of the cotton rhizosphere and the related information changes of the soil-borne disease, because of the complexity of the soil microbial community structure and the limitation of the molecular ecological research methods, such as the PCR-DGGE. As an inportant subsystem of the soil microbial community, the relevance with the soil borne disease and the change information of the cotton rhizosphere microbial community has not been identified yet. This study intends to collect the "health" and the "disorder" two types of cotton rhizosphere soil as the research material in major cotton producing areas of xinjiang with different long-term continuous cropping, using the molecular ecology technology such as high-throughput sequencing. By studying the bacteria and fungi ribosomal sequence information of different samples, depth analysis the succession process of the cotton rhizosphere the bacteria and the fungi community structure, diversity, abundance and other changes under the "health" and the "disorder" with long-term continuous cropping in XinJiang, and find out the district wilt and verticillium wilt of cotton continuous cropping process the original body in rhizosphere enrichment regularity. This paper will provide a theoretical basis for the cotton industry of continuous development and prevention-control to the soil-borne with micro ecological methods.Expected results; cultivated master 2,published SCI articles 2.

前期研究发现新疆棉花在长期连作过程中，土壤微生物群落结构演替规律与连作障碍导致的减产、病虫害的规模性爆发等有很强的关联性。但由于土壤微生物群落结构的复杂性以及PCR-DGGE等分子生态研究方法的局限性，根际微生物群落作为土壤微生态系统的重要子系统，其关键组份及与土传病害相关的微生物类群信息所发生的变化嗜待查明。本研究拟采用高通量测序等分子生态技术，通过对比研究新疆棉田分别演替为"健康"与"失调"两类根际土壤样品中细菌与真菌核糖体序列信息，深度解析新疆棉花根际土壤微生物在长期连作下演替为两种截然不同类型过程中，细菌和真菌群落结构在组成、多样性、丰度等方面发生的变化及规律；了解"健康"与"失调"棉田根际微生物群落结构主要成份类群，查明新疆棉花主要真菌土传病原菌在连作过程中的富集规律。为我区棉花产业的持续发展以及土传病害的微生态防治提供理论基础。预期研究结果，培养硕士生2名，发表SCI论文2篇。

为查明新疆地区棉花长期连作过程中土壤微生物群落结构演替及与连作障碍发生之间的关系，高通量测序法和实时定量PCR方法对比研究了该地区棉花30年内不同年限以及轮作条件下棉花根区土壤中微生物群落结构组成和黄萎病病原物在土壤中的富集过程。.结果：棉花种植使该地区土壤细菌群落多样性增大， 其中Actinobacteria、Acidobacteria、Firmicutes、Nitrospirae、Chloroflexi等菌门种群数量发生较大变化，部分菌门种群数量变化不大。棉花连作过程中与土壤真菌群落的相互影响，棉花栽培仅1年土壤真菌群落结构就发生了重大调整，但新的土壤真菌群落结构需要经历5年以上的多次反复调整后才逐渐稳定下来；新的土壤真菌群落结构是通过Mucorales等6个目种群丰度大量增加，Pleosporales等10个目种群丰度大量减少，部分目种群新出现或者消失等不同类群发生不同的变化而形成的。土壤中黄萎病原菌数量会随着棉花连作年限的延长而快速增加，并且在连作10年左右达到最高值，而病害发生推测还需要气候等其他因素的共同作用。玉米轮作能促使当地土壤真菌群落结构部分组成发生快速改变，同时土壤中黄萎病病原菌数量也会降低,这可能是玉米轮作能恢复农田棉花生产能力的主要原因。当地原生态土壤古菌群落主要由Thaumarchaeota等六个门组成；棉花第一年种植就致使土壤古菌群落香农等多样性指数和可检测到的OTU数量有很大的提高，但原生态土壤特有OTU数依然是最高，达到80；在棉花的长期连作过程中，从门到属的不同分类水平上,都有部分组成在丰度和变化趋势上发生较大改变，且改变的幅度逐年趋小，新的相对稳定的古菌群落系统在棉花连作10年后逐渐形成；玉米轮作仅一年也可以快速改变部分土壤古菌群落组成及丰度，但整体组成仍然变化不大。. 推断耕作是导致当地土壤原生态微生物群落结构发生变化的主要原因，而新的微生物群落结构是在棉花长期栽培及与其配套的耕作方式共同持续胁迫下发生的，并在经历了10年反复波动后逐渐形成并稳定下来，轮作仅可以使部分种类微生物种群快速恢复。