Abstract: Terrestrial plants are colonized by various microorganisms in the rhizosphere, phyllosphere and endosphere. Variations of microorganisms between these niches could affect plant performance. While studies have indicated that microorganisms associated with invasive plants may facilitate their invasion success, niche effects on the composition, function and co-occurrence network of invasive plant microbiomes remain poorly understood. In this study, we investigated the bacterial and fungal communities in the rhizosphere soil, root and leaf endospheres of two invasive plants, Flaveria bidentis and Eclipta prostrata. Flaveria bidentis is a recently introduced species (introduced in 2001), whereas E. prostrata has been invaded in China for over 1000 years. We found that microbial community of F. bidentis and E. prostrata harbored more specialists, fewer unique amplicon sequence variants (ASVs), and lower diversity and network complexity in the leaf endosphere than that in the rhizosphere soil. Moreover, the bacterial and fungal communities in the rhizosphere soil, root and leaf endospheres of F. bidentis were more diverse, included more unique ASVs, and had a higher network complexity than those of E. prostrata. Predicted functional profiles revealed that there were more beneficial bacteria and fewer pathogenic fungi associated with F. bidentis than those with E. prostrata. These results demonstrate that there is a significant niche differentiation in the two invasive plant microbiotas, and this work may also indicate potential impact of residence time of invasive plants on plant-microbe interactions.

Key words: invasive plants, bacteria, fungi, residence time, niche differentiation