Waterlogging-induced restructuring of phyllosphere microbiota associated with mycotoxin accumulation

As waterlogging events intensify and become more frequent in the future, understanding their impact on plant physiology and associated microbes is crucial for alleviating stress in vulnerable species and ecosystems. Despite its importance, our understanding of how phyllosphere microbiota react to waterlogging stress remains limited. This study utilized metagenomic sequencing to assess the effects of waterlogging on microbial diversity and functional activities in different tissues of the maize phyllosphere, focusing specifically on leaves and ears. Our findings indicated that waterlogging significantly affected the maize phyllosphere microbial communities. Also, waterlogging altered the microbial interaction networks by increasing network complexity, enhancing negative interactions, and shifting the relative abundance of key bacterial and fungal genera. Moreover, metagenomic analysis revealed upregulated signaling pathways and oxidative stress responses, particularly within the fungal communities associated with maize ears. Crucially, we identified a higher abundance of genes related to mycotoxin production under waterlogged conditions, leading to elevated mycotoxin levels in ear tissues. These results suggest that waterlogging-induced changes in fungal communities may heighten the risk of mycotoxin contamination in maize. The distinct microbial responses noted between maize leaves and ears further highlight the tissue-specific dynamics of these communities.