Invasion of Celtis tala forests by Ligustrum lucidum in Argentina: impact on soil properties and the arbuscular mycorrhizal community

The arrival of invasive plants can cause drastic changes to ecosystems, such as the displacement of native plant communities and the disruption of ecological functions. <i>Ligustrum lucidum</i> is an invasive tree species that has been registered in numerous regions worldwide. We analysed the effect of the expansion of <i>L. lucidum</i> on the edaphic properties and mycorrhizal fungal communities in forests of <i>Celtis tala</i> located in central-western Argentina. Sampling sites were established along a gradient of invasion, in which we measured the forest structure and soil physical-chemical factors and identified the fungal species using morphological techniques. The analysis of the variance revealed severe changes in the tree structure and a decrease in the concentrations of organic matter and nitrogen in the invaded sites. Thirty-two Glomeromycota species were identified, belonging to 6 families. The abundance of <i>Dentiscutata cerradensis</i> decreased with the invasion, whereas <i>Funneliformis mosseae</i> and <i>Septoglomus constrictum</i> increased. The alpha diversity of the arbuscular mycorrhizal communities showed no differences between sites. The beta diversity decreased at invaded sites, indicating a tendency towards convergence and reduced variability in these communities in the presence of the exotic species.

Influence of Citrus Scion/Rootstock Genotypes on Arbuscular Mycorrhizal Community Composition under Controlled Environment Condition

Citrus is vegetatively propagated by grafting for commercial production, and most rootstock cultivars of citrus have scarce root hairs, thus heavily relying on mutualistic symbiosis with arbuscular mycorrhizal fungi (AMF) for mineral nutrient uptake. However, the AMF community composition, and its differences under different citrus scion/rootstock genotypes, were largely unknown. In this study, we investigated the citrus root-associated AMF diversity and richness, and assessed the influence of citrus scion/rootstock genotypes on the AMF community composition in a controlled condition, in order to exclude interferences from environmental factors and agricultural practices. As a result, a total of 613,408 Glomeromycota tags were detected in the citrus roots, and 46 AMF species were annotated against the MAARJAM database. Of these, 39 species belonged to Glomus, indicating a dominant role of the Glomus AMF in the symbiosis with citrus. PCoA analysis indicated that the AMF community’s composition was significantly impacted by both citrus scion and rootstock genotypes, but total samples were clustered according to rootstock genotype rather than scion genotype. In addition, AMF α diversity was significantly affected merely by rootstock genotype. Thus, rootstock genotype might exert a greater impact on the AMF community than scion genotype. Taken together, this study provides a comprehensive insight into the AMF community in juvenile citrus plants, and reveals the important effects of citrus genotype on AMF community composition.