Rhizosphere microecological characteristics associated with tobacco root-knot nematode disease

Root-knot nematode disease poses a serious threat to the production of tobacco and other crops, but the rhizosphere microecological response mechanisms during disease development remain unclear. In this study, we collected rhizosphere soil from healthy and diseased tobacco plants in typical tobacco-growing areas of Kunming, Yunnan Province, China, and we systematically identified the differences in soil physicochemical properties, enzyme activities, and the microbial community composition and structure based on 16S rDNA and ITS amplicon sequencing. Compared to healthy rhizosphere soil, diseased rhizosphere soil showed significant decreases in pH (from 5.39 ± 0.37 to 4.98 ± 0.23), catalase (CAT) activity (23.89% reduction), and the relative abundance of health-associated microbial taxa, particularly bacterial species Flavisolibacter ginsengisoli (71.05% reduction) and fungal species Fusicolla acetilerea (87.96% reduction). In addition, bacterial communities in diseased soil exhibited a predicted enrichment of functional pathways related to metabolism, environmental adaptation, and stress response (e.g., ansamycin biosynthesis and bacterial chemotaxis). Associations among these observed changes may reflect a cycle potentially linked to disease development. Conversely, healthy soils showed a higher pH, CAT activity, and relative abundance of health-associated microbial taxa. Together, these results reveal the coordinated changes among soil physicochemical factors, enzyme activities, and microbial communities and suggest an association between rhizosphere microecological imbalance and root-knot nematode disease. These findings provide a theoretical basis for future studies exploring the targeted regulation of soil microecology for managing this disease.