黄芪根腐病病株和健株根围微生物菌群变化分析

通过分析黄芪根腐病病株和健株根围微生物菌群的变化,探究根腐病的发病机理,寻找预警病害发生的生物指示因子,为土壤微生态的生物调控提供依据。试验通过菌落计数、PCR-DGGE和16S rRNA V3区基因测序的方法,分析不同年限下黄芪根围病/健土中微生物区系、多样性及群落结构的变化。结果表明:细菌作为黄芪根围土中的优势种群,是影响病土中微生物数量升高的关键因子,其多样性降低是影响病害加重的主要原因之一。假单胞菌属Pseudomonas和无色杆菌属Achromobacter为土壤中的优势菌群,健土中的1号和4号特异条带分别为未培养的假单胞菌Uncultured Pseudomonas sp.和荧光假单胞菌P.fluorescens;6号未培养假单胞菌Uncultured Pseudomonas sp.的丰度与根腐病发病率负相关,16号无色杆菌Achromobacter sp.的丰度则在3年生土壤中显著升高,随后急剧下降。上述4个菌可作为潜在的土壤健康或发病指示因子进一步研究。

Changes of microbial community in root zone soil of Astragalus membranaceus suffering from root rot disease

By analyzing the changes of microbial community in root zone soil of Astragalus membranaceus diseased and healthy plants, the study aimed at exploring the pathogenesis mechanism and biological warning indicators for the root rot disease occurrence so as to provide a theoretical basis for the biological regulation of soil micro-ecology. The microbial community in the diseased and healthy soil samples was examined through plate colony counting, PCR-DGGE and 16S rRNA V3 gene sequencing to probe into the changes of the microflora, microbial diversity and community structure in different planting years. The results showed that bacteria, as the dominant flora in the soil, were a key factor resulting in significant increase of microorganism quantity in diseased soils. The significant decrease in the bacterial diversity was one of the main causes for the increase of root rot disease incidence. Pseudomonas and Achromobacter were the dominant genera in the root zone soil. The specific bands No.1 and No.4 in the healthy soil were Uncultured Pseudomonas sp. and P. fluorescens, respectively; the abundance of No.6 Uncultured Pseudomonas sp. was negatively correlated with the root rot incidence, and No.16 Achromobacter sp. increased remarkably at the 3rd year and then began to decrease sharply. The four strains were worth further study as the potential biological indicator of soil health and disease occurrence in the future.