Changes in Soil Fungal Communities Following Exogenously Added Tobacco Mosaic Virus Disease.

The microbial communities inhabiting the root zone of plants play a crucial role in their development,. However, the interaction between root-associated microbial populations and soil physicochemical properties, including changes in fungal biodiversity, remains an area of ongoing investigation. Despite extensive research, the effects of tobacco mosaic virus (TMV) infection on Nicotiana benthamiana are still inadequately understood, particularly with regard to its long-term impacts and physiological responses. We used amplicon sequencing to examine the succession of fungal communities in the root-associated soils of plants from both diseased (YTD) and healthy (YTW) soil groups after TMV inoculation and to determine their potential impact on plant health. In the YTW soil group, we determined the relationship between fungal communities and TMV resistance and observed a more intricate fungal network structure compared with that found in YTD. Over time, fungal communities became predominant and included beneficial fungi, such as Penicillium, Mortierella, and Cladosporium, and the common pathogenic fungus Fusarium. Our findings indicate that TMV resistance in healthy plants may be mediated not only by beneficial fungi but also by specific fungal taxa conventionally classified as pathogens, potentially through activation of systemic acquired resistance pathways. Moreover, TMV inoculation of Nicotiana benthamiana altered the physicochemical properties of the root-associated soil, with significant variations in available phosphorus, nitrate nitrogen, total nitrogen, and soil organic carbon under different soil conditions. These results enhance our understanding of fungal microbial resistance to TMV, suggesting that more complex microbial communities or soil-associated rhizosphere microbes enriched in beneficial fungi are more conducive to enhancing plant resistance to TMV, which could enhance tobacco yield and serve as a reference for biological control strategies.