Native and Invading Yellow Starthistle (Centaurea solstitialis) Microbiomes Differ in Composition and Diversity of Bacteria

Abstract

Invasive species could benefit from being introduced to locations with more favorable species interactions, including the loss of enemies, the gain of mutualists, or the simplification of complex interaction networks. Microbiomes are an important source of species interactions with strong fitness effects on multicellular organisms, and these interactions are known to vary across regions. The highly invasive plant yellow starthistle (Centaurea solstitialis) has been shown to experience more favorable microbial interactions in its invasions of the Americas, but the microbiome that must contribute to this variation in interactions is unknown. We sequenced amplicons of 16S rRNA genes to characterize bacterial community compositions in the phyllosphere, ectorhizosphere, and endorhizosphere of yellow starthistle plants from seven invading populations in California, USA, and eight native populations in Europe. We tested for the differentiation of microbiomes by geography, plant compartment, and plant genotype. Bacterial communities differed significantly between native and invading plants within plant compartments, with consistently lower diversity in the microbiome of invading plants. The diversity of bacteria in roots was positively correlated with plant genotype diversity within both ranges, but this relationship did not explain microbiome differences between ranges. Our results reveal that these invading plants are experiencing either a simplified microbial environment or simplified microbial interactions as a result of the dominance of a few taxa within their microbiome. Our findings highlight several alternative hypotheses for the sources of variation that we observe in invader microbiomes and the potential for altered bacterial interactions to facilitate invasion success.IMPORTANCEPrevious studies have found that introduced plants commonly experience more favorable microbial interactions in their non-native range, suggesting that changes to the microbiome could be an important contributor to invasion success. Little is known about microbiome variation across native and invading populations, however, and the potential sources of more favorable interactions are undescribed. Here, we report one of the first microbiome comparisons of plants from multiple native and invading populations, in the noxious weed yellow starthistle. We identify clear differences in composition and diversity of microbiome bacteria. Our findings raise new questions about the sources of these differences, and we outline the next generation of research that will be required to connect microbiome variation to its potential role in plant invasions.

The Rhizosphere Microbiome of Mikania micrantha Provides Insight Into Adaptation and Invasion

“…Moreover, the NMDS plots showed that there was a clear separation between the pot experiment and field invaded site, indicating that rhizosphere microbial community was largely influenced by environmental conditions (Figure 1C). The dominant prokaryotic phyla found in the control and rhizosphere community included Proteobacteria, Actinobacteria, Acidobacteria, Planctomycetes, and Chloroflexi (Figure 1D), which was consistent with previous studies (Lu-Irving et al, 2019). The community differences between the control soil and rhizospheres of M. micrantha and native plants were also explored.…”

Microbiome of the Successful Freshwater Invader, the Signal Crayfish, and Its Changes along the Invasion Range

“…Also, we examined whether differences in the microbiome occur during the invasion process and whether they are more pronounced along different river sections (downstream versus upstream; a proxy for the effect of microhabitat characteristics) or between crayfish populations of different density and species composition (core versus front; a proxy for the effect of changing population characteristics along the invasion range, that is, nonrandom dispersal and density-dependent effects). As effects of both resident and invader microbiota are increasingly recognized among the drivers of invasion success ( 35 , 36 ), our results offer a baseline for better understanding their role and dynamics during range expansion.…”

The diversity and distribution of endophytes across biomes, plant phylogeny and host tissues: how far have we come and where do we go from here?

“…Interestingly, the few studies we encountered that surveyed endophytic microbiomes of invasive plants in both their native and invaded ranges found that endophyte assemblages differed between ranges. For instance, Lu‐Irving and colleagues () report reduced richness in phyllosphere and endophytic root bacteria in the invaded portion of the range of Centaurea solstitialis compared with the native range. Similarly, Shipunov and colleagues () report a wholesale shift in the fungal endophyte assemblage within the leaves of Centaurea stoebe in invaded versus native portions of its range.…”