Abstract:

To study the relationship between tobacco root-knot nematode disease and rhizosphere soil microbial communities, high-throughput sequencing was used to study the microbial diversity, composition structure and function of rhizosphere soil in healthy and diseased tobacco fields. The results show that there is no significant difference in the Alpha diversity of the rhizosphere soil microbial communities between healthy and diseased tobacco fields. Beta diversity analysis shows that the distribution of samples from healthy and diseased tobacco fields is basically the same. The bacterial and fungal microbial communities in the rhizosphere soil of healthy and infected tobacco fields are similar in composition at the phylum level, but there are differences in species abundance. Acidobacteria, Actinobacteria, Basidiomycota and Chytridiomycota are dominant in healthy tobacco fields, while Proteobacteria and Gemmatimonadetes, Ascomycoda and Mortierellomycota are dominant in diseased tobacco fields. At the genus level, the microbial community composition of rhizosphere soil bacteria and fungi are basically the same, but there is significant difference in the microbial species abundance between healthy and root-knot nematode-infected tobacco fields, and the pathogenic bacteria such as Cylidrocapon, Fusarium are dominant in the diseased tobacco field. At the species level, Actinoallomurus spadix and Arhrobacter ramosus in healthy tobacco fields are significantly different from those in diseased tobacco fields. Through the prediction analysis of rhizosphere soil microbial function, it is found that the functional composition of fungi and bacteria in diseased and healthy tobacco fields are similar, but the functional abundance of diseased tobacco fields is higher than that of healthy tobacco fields. Therefore, infection of nematodes is not directly related to the composition and diversity of the rhizosphere soil microbial community, but might be closely related to the abundance of certain species and sample functional abundance. The study could provide a theoretical basis for controlling tobacco root knot nematode disease by regulating rhizosphere microbial community structure.

Key words: tobacco, rhizosphere soil microorganism, root knot nematodes, microbial diversity, community structure, species abundance, functional abundance