Differences in soil microbial community and function between healthy and clubroot diseased plants of Chinese cabbage

Clubroot disease severely restricts the development of the cruciferous vegetables industry. Changes in soil microbial diversity and composition are not only closely related to cruciferous crop clubroot disease but are also crucial to soil health, sustainable development of agricultural production systems, and human health. Therefore, it is necessary to understand the differences in microbial community structure between clubroot and bulk soil. Illumina MiSeq high-throughput sequencing technology was used to sequence bacterial 16S rDNA and fungal ITS genes in the bulk soil of healthy (H) and clubroot infected (D) Chinese cabbage. The results were compared with relevant databases after quality control. The physical and chemical properties of the bulk soil were determined, and the differences in the microbial community structure and composition between samples were analyzed. The relationship between soil physical and chemical properties, soil microbial community, and clubroot disease was discussed, and the function of bacteria and fungi in the samples was predicted. The results showed that: 1) the evenness and diversity of the bacterial community in the bulk soil of healthy Chinese cabbage plants were higher than those in the bulk soil of Chinese cabbage plants with clubroot disease. The richness, evenness, and diversity of fungal communities in the bulk soil of Chinese cabbage plants with clubroot disease were higher than those in the bulk soil of healthy Chinese cabbage plants, indicating that clubroot disease greatly influenced the composition of the soil fungal community. 2) Actinobacteria, Proteobacteria, Firmicutes, Chloroflexi, Acidobacteria, and Gemmatimonadetes were the dominant phyla of bacteria in soil samples. Bacillus, Gaiella, Defluviicoccus, Clostridium, and Nocardioides were the dominant genera of bacteria in the soil samples. The dominant fungal phyla in the bulk soil were Ascomycota, Mortierellomycota, Basidiomycota, and Olpidiomycota. The main fungal genera identified were Gibberella, Mortierella, Thielavia, and Basipetospora. 3) Metabolism, environmental information processing, cellular processes, and organic systems are four types of bacterial functions with significant differences in bulk soil bacterial communities between healthy and diseased plants; the functional abundances of Gibberella, Thielavia, Kernia, and Fusarium in bulk soil fungal communities of diseased plants were higher than those of healthy plants. 4) Principal coordinate analysis showed that the bacterial and fungal community structures in the bulk soil of healthy and diseased plants were significantly different. Redundant analysis showed that pH, total nitrogen, available nitrogen, available potassium, and cation exchange capacity were the main factors influencing microbial community changes in bulk soil. This study provides a new basis for the study of rhizosphere microbial flora of cruciferous crops and provides the possibility for the study of the method of controlling clubroot by beneficial synthetic bacteria-mediated pathogenic bacteria, as well as a way to alleviate soil degradation and rebuild healthy soil.