Comprehensive analysis of vegetation and rhizosphere bacterial composition after the invasion of Chinese tallow ( Triadica sebifera ) in Miyajima Island, SW Japan

Chinese tallow, Triadica sebifera (L.) Small (Euphorbiaceae) is an invasive plant species causing ecological issues in various regions. Investigating the rhizobacterial community following and exploit whether above-ground plant communities and below-ground rhizobacterial communities exhibit a coupled response to its invasions is significant. Here we employed next-generation sequencing and sophisticated ecological analysis techniques to elucidate the rhizobacterial communities of T. sebifera in Miyajima Island, SW Japan. We analyzed soil samples collected from seven sites over four sampling times (total 76 samples), comparing the rhizobacterial communities associated with T. sebifera to those surrounding native plants’ and in control soil sites. Our findings indicated a significantly higher bacterial abundance in T. sebifera rhizosphere compared to native plants and control conditions but there were no significant changes seasonally. Spatial variability was observed in the rhizosphere bacterial communities of T. sebifera in Miyajima, a pattern notably influenced by environmental factors like soil pH and phosphorus concentrations. Our binary tanglegram analysis revealed a correlation between the above-ground plant communities and the below-ground rhizobacterial communities in areas where T. sebifera is located. Additionally, T. sebifera growing in nutrient-poor soil collected from Miyajima Island exhibited a rhizobacterial community structure resembling that of the local plants, suggesting adaptability of T. sebifera ’s rhizosphere to local soil conditions. We also identified Proteobacteria as a significant bacterial group within T. sebifera rhizosphere, highlighting their potential role in the invasive success of the plant by Random Forest algorithm. This research provides new insights into the complex interactions between T. sebifera and its associated rhizobacterial communities and contributes to our understanding of its ecological invasion mechanisms.