COS 278-2 - Microbial communities in the leaf, roots and rhizosphere of an invasive shrub, Ardisia crenata, differ between its native and invaded range
Understanding why only some exotic plants become invasive is important for ecology and management of invasive plants. To answer this question, plant-microbe interactions are receiving increasing attention. Exotic plants interact with various microbes in introduced ranges that might be different from those in their native range. Yet, such differences and how they influence the invasiveness remain unexplored. Ardisia crenata is a forest understory shrub native to East Asia and highly invasive in the southeastern US, including north-central Florida. Local stem density is much higher in the US than in Japan. Given that there are no conspicuous herbivores within native range, we hypothesize that differences in microbial community between native and invasive populations contribute to invasion success of A.crenata. To test this hypothesis, we (1) compared the microbial community composition and diversity of A.crenata between the native and invasive populations, (2) summarized microbial community structure based on phylogenetic taxon and functional guilds. Thirty individuals of A.crenata were collected from the native (Japan) and exotic range (Florida, USA). DNA was extracted from leaf edge, leaf center, root endosphere and rhizosphere soil. The composition of fungal and bacterial OTUs (ITS and 16S region) were described by DNA amplicon sequence (Illumina Miseq).
Results/Conclusions
The diversity of microbial communities differed markedly in root endosphere, with lower diversity in invaded than in native populations for both fungi and bacteria. This indicates that some of the microbes associated with native populations are absent in the invaded region. Microbial community structure differed greatly among leaf center, leaf edge, root endosphere, and rhizosphere soil for bacteria and fungi, as well as between the native and invaded sites. Especially, the community structure of endophytic fungi in leaves differed greatly between the native and invaded ranges, and certain fungi that were rare in the native range were present at a very high frequency in the invaded range, indicating the formation of new host-endophyte interactions in the invaded range. In addition, some pathogenic fungi that appeared only in the native range were detected in leaves and root endosphere, suggesting release from enemies which suppress stem-density of A.crenata in the native range. In summary, we have successfully identified several candidate plant-microbe interactions at the microbial species level that are key to the invasion success of A.crenata.
