关键词: 烟草镰刀菌根腐病, 连作, 土壤微生物, 根际土壤, 多样性, 高通量测序

Abstract: In order to investigate the changes of bacterial and fungal communities in the rhizosphere soil of healthy and root rot‑infected tobacco plants in continuous cropping tobacco fields，with soil that was abandoned for more than two years as a control（CK），high‑throughput sequencing technology was used to compare and analyze rhizosphere soil microbial diversity of healthy（HT2，HT4，HT8）and diseased（ST2，ST4，ST8）plants in continuous cropping fields of 2，4 and 8 years and the effects of soil environmental factors on microbial community structure. The results showed that the relative abundance of dominant bacteria in the rhizosphere soil of healthy and diseased plants increased by 9.2%—29.5% and 26.4%—29.8%，respectively in continuous cropping tobacco fields；the relative abundance of the dominant fungi decreased by 53.4%—65.7% and 19.0%—67.8%，respectively. Among them，the amplification of dominant bacteria relative abundance in Gemmatimonas，Frateuria，Gemmata were largest，and the relative abundance of dominant fungi decreased most in Penicillium.In addition to the decrease in the relative abundance of the pathogenic fungi Fusarium in the HT2 sample，the relative abundance of the pathogenic fungi Fusarium in the healthy plants（HT4 and HT8）and diseased plants samples increased significantly（123.4%—576.8%）.The bacterial community richness and diversity in the rhizosphere soil generally increased with the continuous cropping years，whilst the fungal community richness and diversity showed a trend of first decreasing and then increasing with the continuous cropping years.The bacterial and fungal community compositions of rhizosphere soil were different among healthy plants and among diseased plants samples with different continuous cropping years. Soil available potassium content and pH value were the main chemical factors affecting the distribution of soil bacterial communities，with a contribution degree of 8.80% and 8.62%，respectively，available phosphorus content was the main chemical factor affecting the distribution of fungal communities，with a contribution degree of 11.64%.In conclusion，the richness of bacterial community，diversity and dominant population in rhizosphere soil of continuous cropping tobacco and tobacco infected with root rot disease increased，but the richness of dominant fungal population and the relative abundance of beneficial fungal flora decreased，while the relative abundance of pathogenic fungi increased. Reducing the duration of continuous cropping and timely removal of diseased tobacco plants are the key practices to solve the imbalance of microbial community structure in tobacco fields.

Key words: Tobacco Fusarium root rot, Continuous cropping, Soil microbe, Rhizosphere soil, Diversity, High?throughput sequencing