Patricia Silva-Flores

Wildfires are increasing in frequency and severity worldwide, with long-lasting effects on forest vegetation and fungal communities essential for seedling establishment and forest resilience. Nothofagus pumilio, the dominant tree of South American temperate forests, forms key fungal symbioses but shows limited post-fire regeneration. Root-fungal community responses in seedlings under long-term post-fire conditions remain unknown. We characterized root-associated fungal communities in N. pumilio seedlings growing in burned (eight years post-fire) and unburned forest of the southern Andes, using ITS1 metabarcoding. We assessed diversity, composition, and abundance of root-associated fungi, including ectomycorrhizal fungi and dark septate endophytes. Diversity and evenness were significantly lower in burned than in unburned forest, with no significant differences in richness or composition. The ectomycorrhizal genus Cortinarius was less abundant in burned-forest seedlings. In seedlings from burned forest, the dark septate endophyte Cadophora was significantly more abundant, whereas Exophiala and Cladophialophora were less abundant than in unburned forest. Despite these shifts, burned areas retained root-associated fungal taxa linked to plant-beneficial functions and shared most OTUs with unburned forest, indicating an incomplete but ongoing recovery. Further research should evaluate how these shifts affect early seedling performance, and assess the role of persistent beneficial taxa for restoration after wildfires.

Societal Impact Statement: Wine production has a significant impact on the global economy. Despite this, the microbial composition of the terroir has not been studied sufficiently, particularly in the southern hemisphere. Here, we investigated how bulk soil fungal communities are affected by several abiotic and biotic factors across 1,000 km of Chilean vineyards. We found that geographical distance was the main driver of vineyard soil fungal communities. Irrespective of variety, older vineyards host a higher relative abundance of arbuscular mycorrhizal fungi (AMF) and a lower relative abundance of plant pathogenic fungi. This result could lead to significant recommendations on when to apply AMF‐based inoculants.Summary: The microbial dimension of the terroir has been increasingly recognized as an essential factor determining vineyard productivity and quality. Despite this, few studies have analyzed the factors affecting soil fungal communities of vineyards in the southern hemisphere. Across a 1,000 km gradient encompassing 34 Chilean vineyards, we investigated the effects of grapevine variety, geographical distance, maturity, and soil chemical properties on the diversity and composition of soil fungi. We implemented standard soil chemical analyses and ITS‐based DNA metabarcoding of bulk soil. We found that the total soil fungal composition was significantly affected by geographical distance but not by grapevine variety and maturity. Soil chemical dissimilarity also significantly affected soil fungal composition. When analyzing specific fungal guilds, we found a contrasting successional pattern: arbuscular mycorrhizal fungal relative abundance was significantly higher at medium and old‐maturity vineyards compared with young vineyards, on which plant pathogenic fungi had a markedly lower abundance. Our results present several caveats: the molecular marker was not the most commonly used for arbuscular mycorrhizal fungi, bulk soil was sampled (instead of roots), and all abundances were relative. Still, this study constitutes one of the most extensive studies on soil fungi – both for vineyards and Chile – and might have practical implications, as knowing the drivers of fungal and mycorrhizal biodiversity can inform agricultural management decisions.

Summary: Global assessments of mycorrhizal symbiosis present large sampling gaps in rich biodiversity regions. Filling these gaps is necessary to build large‐scale, unbiased mycorrhizal databases to obtain reliable analyses and prevent misleading generalizations. Underrepresented regions in mycorrhizal research are mainly in Africa, Asia, and South America. Despite the high biodiversity and endemism in these regions, many groups of organisms remain understudied, especially mycorrhizal fungi. In this Viewpoint, we emphasize the importance of inclusive and collaborative continental efforts in integrating perspectives for comprehensive trait database development and propose a conceptual framework that can help build large mycorrhizal databases in underrepresented regions. Based on the four Vs of big data (volume, variety, veracity, and velocity), we identify the main challenges of constructing a large mycorrhizal dataset and propose solutions for each challenge. We share our collaborative methodology, which involves employing open calls and working groups to engage all mycorrhizal researchers in the region to build a South American Mycorrhizal Database. By fostering interdisciplinary collaborations and embracing a continental‐scale approach, we can create robust mycorrhizal trait databases that provide valuable insights into the evolution, ecology, and functioning of mycorrhizal associations, reducing the geographical biases that are so common in large‐scale ecological studies.

Soil characteristics, land management practices, and plant genotypes influence arbuscular mycorrhizal fungi (AMF) communities, leading to the proliferation of AMF taxa with different growth and nutritional outcomes in their hosts. However, the specific patterns driving these relationships are still not well understood. This study aimed to (1) evaluate the influence of soil characteristics, land use, and rootstock on AMF diversity and community structure and (2) assess the effect of those AMF communities on grapevine growth and nutrition. Soil samples were collected from vineyard and non-agricultural areas in Lisbon and Pegões, Portugal, and trap cultures established using Richter 110 and 1103 Paulsen rootstocks. After 3.5 months growth under greenhouse conditions, root-associated AMF communities were assessed by amplicon metagenomic sequencing using AMF-specific primers. Alpha diversity was only influenced by the soil type, while in β-diversity, an interaction was found between the soil type and land use. Both diversity measures were positively correlated with foliar K and negatively with leaf Mn and Mg. Notably, the concentrations of these nutrients were highly correlated with the relative abundance of operational taxonomic units (OTUs) within the genera Glomus, Rhizophagus, and Claroideoglomus. These results are valuable for supporting AMF selection for improved plant nutrition based on varying soil types and land uses.

Nothofagus alessandrii (ruil) is an endangered relict species, endemic to the Mediterranean area of Chile, and one of the most threatened trees in the country. Its natural distribution area has been greatly reduced by the effect of human activities; the remaining fragments are mostly intervened and highly deteriorated as a habitat and refuge for the associated biodiversity. In order to produce healthy and resistant nursery plants for recovery and restoration of N. alessandrii forests, this study evaluates the early effects of mycorrhizal fungal inoculum (MFI) combined with fertilization on the cultivation of seedlings. The experiment was established under a completely randomized design with a factorial arrangement of the mycorrhizal factors (M0 = without mycorrhizal, M1 = Thelephora sp. and M2 = Hebeloma sp.) and fertilization (F1 = standard fertilization and F2 = intensive fertilization), with three replicates of each combination, for each type of plant (P1 = plants from one season and P2 = plants from two seasons). Each experimental unit corresponded to a group of 20 plants, with 720 plants in the test. The results indicate that application of fertilizer and MFI significantly affects some growth and photosynthesis parameters of ruil plants in one and two seasons. The morphological parameters obtained in the study show shoot height values ranging between 67 and 91 cm for P1 and between 96 and 111 cm for P2; while, for shoot diameter, values ranged between 7.91 and 8.24 mm for P1 and between 10.91 and 11.49 mm for P2. Although formation of fully developed mycorrhizal roots was not observed during the assay period, we conclude that inoculation of mycorrhizal fungi combined with fertilization could be an efficient strategy to produce a quality plant, in addition to maintaining a high photosynthetic capacity and, therefore, a higher percentage of survival in the field.

Societal Impact Statement: Mycorrhizal associations are acknowledged as key components of global ecosystem functioning. This is especially relevant in the context of global change, since they contribute to the amelioration of adverse soil conditions and play crucial roles in agriculture. Generally speaking, the lay public is uninformed on the importance of mycorrhizal fungi and symbiosis to our planet. Therefore, mycorrhizal scientific outreach activities are of paramount importance in order to bridge the aforementioned gap. We think that informing people about the benefits of mycorrhizal fungi and symbiosis in the face of global change, will raise general awareness of relevant research and aid conservation efforts.Summary: Science outreach has become a particularly important duty in shortening the knowledge gap between scientists and the public, in order to strengthen societal decision‐making power in the global change crisis. Mycorrhizal fungi and mycorrhizal symbioses are key components of terrestrial ecosystems that contribute significantly to endure and reduce certain negative global change effects. Their importance has been gaining recognition in academic circles, but not among the general public. The aim of this article is to encourage as many mycorrhizal fungi researchers around the world as possible to build, through science outreach, a bridge between their scientific work and public interest. To this end, we conducted a review and discussed the relationship between global change and the mycorrhizal symbiosis. We highlight potential audiences, tools, resources, activities, outreach models, pros and cons, as well as the quantification potential for the outreach activities success. We extend an invitation to all mycorrhizologists around the world to contribute with mycorrhizal outreach material. Contributions will become available on the South American Mycorrhizal Research Network website for individuals or organizations interested in starting or innovating in mycorrhizal science outreach activities. Finally, the hashtag #mycorrhizalscienceoutreach is proposed to be used whenever a mycorrhizal fungi‐related science outreach activity is shared in social media.

Energy crops have proved to be a viable alternative to fossil fuels. However, high biomass production always means that large quantities of nutrients from the soil are removed at harvest. The goal of this work was to estimate nutrient (nitrogen, phosphorous, potassium) use efficiency (NUE) and nitrogen balance in an eight-year-old Populus deltoides clone Lux, short rotation forestry under two cutting cycles, every two (biennial) and three (triennial) years, carried out under Mediterranean climate conditions. Results indicate that NUE, for all the analyzed elements, contained variations with slightly higher values for nitrogen and phosphorous in the triennial cycle. Although poplar cultivation has a positive nutrient efficiency, in terms of nitrogen, there is significant loss of this element in the crop cycle.