RÉSUMÉ
The root rot disease is a common disease during the cultivation of Panax quinquefolius. In order to provide some clues for solving the root rot disease of P. quinquefolius, the relationship between rhizosphere soil fungal communities and root rot of P. quinquefolius was investigated in this study. The diversities and the changes of fungal communities structure in blank control group (group C), rhizosphere soil of healthy P. quinquefolius (group N) and occurrence of root rot in rhizosphere soil of P. quinquefolius (group R)were analyzed byusing the Illumina MiSeq high-throughput sequencing technology. A total of 505 968 high-quality sequences were obtained through high-throughput sequencing and the rare faction curves analysis showed that the sequencing depth was sufficient and the sampling was reasonable. The fungal communities structure of rhizosphere soil samples mainly belonged to 9 phylums including Ascomycota(54.9%), Basidiomycota(5.6%), etc., and the dominant specie was Ascomycota of the total fungal identified, respectively. The 115 genera of fungi were tested, including Monographella (3.9%), Archaeorhizomyces (3.9%), Mortierella, etc., and the dominant specie was Monographella. At the genus level, the abundance of Monographella and Mortierella in group R increased significantly compared with the abundance in groups C and N. Alpha diversity index of species showed that the diversity index of fungal communities reduced and the numbers of fungi reduced in group N and R, compared with group C, and reaching the minimum in group R. Beta diversity index of species showed that there was a significant difference in the fungal communities structure in each sample. In addition, the heat map analysis revealed that the dominant fungal genera were significantly different among the each sample. The proportion of Monographella and Mortierella in group R was significantly higher than that in group C and N, while the proportion of Trichoderma,Penicillium and Cadophora in group R was extremely low. The proportion of Phoma and Gibberella in group R increased significantly compared with group C. This study clarified the decline of diversity index and the imbalance of community structure in fungi may lead to the occurrence of root rot in P. quinquefolius by analysis of fungal diversity and community composition in the rhizosphere soil of P. quinquefolius in this study, which provided a theoretical basis for the prevention and treatment of occurrence of root rot in P. quinquefolius.