The invader Carpobrotus edulis promotes a specific rhizosphere microbiome across globally distributed coastal ecosystems.

The importance of plant-microbe interactions to the success of invasive plants has rarely been studied at a global scale. Carpobrotus edulis (L.) N. E. Br is an aggressive invader in many areas around the world, forming dense mats in coastal environments. In an approach at a large geographical scale, over a wide latitudinal and climatic range, we tested the ability of C. edulis to alter the local bacterial and fungal community structure and microbial activity in eight invaded coastal locations. The factors invasiveness and geographical location had a significant effect on the soil microbiota, the microbial community composition and structure from the rhizosphere of native and C. edulis plants being distinct in every location. The effect of the invader on all the chemical, physico-chemical, and microbiological properties studied depended on the invaded location. The soil bacterial and fungal community composition and structure were related to the soil available nutrients and mean annual rainfall, and those of the soil bacterial community were also linked to the soil respiration and latitude. Overall, our results reveal that the ability of the invader C. edulis to alter soil microbial community structure harboring a specific microbiome was widespread across a large invaded range - leading to concurring changes in the rhizosphere microbial functioning, such as nutrient cycling.

The unspecificity of the relationships between the invasive Pennisetum setaceum and mycorrhizal fungi may provide advantages during its establishment at semiarid Mediterranean sites.

The involvement of mutualistic plant-fungal interactions in invasion processes, especially in some climatic regions including semiarid areas, has not been sufficiently investigated. We compared the arbuscular mycorrhizal fungi (AMF) communities hosted by the invasive plant Pennisetum setaceum with those from the co-occurring native Hyparrhenia hirta at five Mediterranean semiarid locations with different edaphic characteristics. Illumina technology was used to investigate the AMF communities in the roots. The subsequent multivariate analysis showed that native and non-native host plants shared a similar AMF community, whereas the invaded locations differed in AMF communities harbored in the plant roots. The indicator species analysis revealed the absence of indicator virtual taxa for the fungal communities of the roots of native or invasive plants. In contrast, different numbers of indicator species were recorded in different sampling locations. According to the canonical correspondence analysis, the variability in the AMF communities between sampling sites was related to changes in soil total carbon, electrical conductivity, respiration, and protease and urease activities. These findings reveal the unspecificity of P. setaceum in relation to its association with the AMF community encountered in the invaded locations, which could have facilitated its successful establishment and spread.

Arbuscular mycorrhizal fungi inoculation mediated changes in rhizosphere bacterial community structure while promoting revegetation in a semiarid ecosystem.

The main goal of this study was to assess the effect of the inoculation of four autochthonous shrub species with the arbuscular mycorrhizal (AM) fungus Rhizophagus intraradices on the rhizosphere bacterial community and to ascertain whether such an effect is dependent on the host plant species. Additionally, analysis of rhizosphere soil chemical and biochemical properties was performed to find relationships between them and the rhizosphere bacterial communities. Non-metric multidimensional scaling analysis and subsequent permutational multivariate analysis of variance revealed differences in bacterial community composition and structure between non-inoculated and inoculated rhizospheres. Moreover, an influence of the plant species was observed. Different bacterial groups were found to be indicator taxonomic groups of non-inoculated and inoculated rhizospheres, Gemmatimonadetes and Anaerolineaceae, respectively, being the most notable indicators. As shown by distance based redundancy analysis, the shifts in bacterial community composition and structure mediated by the inoculation with the AM fungus were mainly related to changes in plant nutrients and growth parameters, such as the shoot phosphorus content. Our findings suggest that the AM fungal inoculum was able to modify the rhizosphere bacterial community assemblage while improving the host plant performance.

Arbuscular mycorrhizal fungal assemblages in biological crusts from a Neotropical savanna are not related to the dominant perennial Trachypogon.

Knowledge of the arbuscular mycorrhizal fungal assemblages in the Trachypogon savanna ecosystems is very important to a better understanding of the ecological processes mediated by this soil microbial group that affects multiple ecosystem functions. Considering the hypothesis that the biocrusts can be linked to vegetation through the arbuscular fungi mycelial network, the objectives proposed in this study were to determine (i) whether there are arbuscular mycorrhizal fungi (AMF) in the biocrusts (ii) whether arbuscular mycorrhizal fungal assemblages are linked to the Trachypogon patches, and (iii) whether the composition of the assemblages is related to soil properties affected by microbiological activity. The community structure of the AMF was investigated in three habitats: rhizospheric soil and roots of Trachypogon vestitus, biological soil crusts, and bare soil. The canonical correspondence analysis showed that two soil properties related to enzymatic activity (protease and ß-glucosidase) significantly affected the community composition of the AMF. The biocrusts in the Venezuelan savanna are colonized by an AM fungal community linked to that of the bare soil and significantly different from that hosted by the roots of the surrounding T. vestitus, suggesting that assemblages of AMF in biocrusts might be related more closely to those of annual plant species appearing in favorable conditions.