Richness of arbuscular mycorrhizal fungi (Glomeromycota) along a vegetation gradient of Brazilian Cerrado: responses to seasonality, soil types, and plant communities

Morphological spore-based characterisation and molecular approaches reveal comparable patterns in glomeromycotan communities

Traditionally, characterisation and comparison of AMF communities has been carried out by morphological identification of asexual spores in soil. In recent decades, molecular methods such as soil metabarcoding have become more popular than morphological identification of spores, but direct comparisons of the efficiency of both approaches have been rare. In this study, we compared AMF communities in soil samples from vegetable farms using both morphological and molecular methods (internal transcribed spacer, ITS, markers). In addition, we performed a systematic literature search and retrieved nine studies that analysed AMF communities using both approaches in the same soil samples, mostly in agroecosystems. Our results show that AMF communities determined by morphological spore-based identification are different than those determined by molecular genetic markers, but not as often claimed. In some cases, the morphological spore-based characterisation of spores revealed more diverse glomeromycotan communities. Moreover, in several cases the spore-based methods recovered taxa that the molecular methods did not, while in other cases the opposite was observed. The field and literature-based results of this study indicate that for a comprehensive and exhaustive characterisation of AMF communities it is necessary to combine both approaches. However, if the aim is to compare communities under different environmental conditions, both approaches provide comparable patterns.

Heterogeneity in Arbuscular Mycorrhizal Fungi and Plant Communities of the Brazilian Cerrado, Transitional Areas toward the Caatinga, and the Atlantic Forest

The Cerrado is the most diverse tropical savanna worldwide and the second-largest biome in South America. The objective of this study was to understand the heterogeneity and dynamics of arbuscular mycorrhizal fungi (AMF) in different types of natural Cerrado vegetation and areas that are transitioning to dryer savannas or tropical rainforests and to elucidate the driving factors responsible for the differences between these ecosystems. Twenty-one natural sites were investigated, including typical Cerrado forest, typical Caatinga, Atlantic Rainforest, transitions between Cerrado and Caatinga, Cerrado areas near Caatinga or rainforest, and Carrasco sites. Spores were extracted from the soils, counted, and morphologically analyzed. In total, 82 AMF species were detected. AMF species richness varied between 36 and 51, with the highest richness found in the area transitioning between Cerrado and Caatinga, followed by areas of Cerrado close to Caatinga and typical Cerrado forest. The types of Cerrado vegetation and the areas transitioning to the Caatinga shared the highest numbers of AMF species (32-38). Vegetation, along with chemical and physical soil parameters, affected the AMF communities, which may also result from seasonal rainfall patterns. The Cerrado has a great AMF diversity and is, consequently, a natural refuge for AMF. The plant and microbial communities as well as the diversity of habitats require urgent protection within the Cerrado, as it represents a key AMF hotspot.

The Ectomycorrhizal Fungi and Soil Bacterial Communities of the Five Typical Tree Species in the Junzifeng National Nature Reserve, Southeast China

To explore the contribution of microorganisms to forest ecosystem function, we studied the ectomycorrhizal (ECM) fungal and soil bacterial community of the five typical tree species (Pinus massoniana, PM; Castanopsis carlesii, CC; Castanopsis eyrei, CE; Castanopsis fargesii, CF; and Keteleeria cyclolepis, KC) at the Junzifeng National Nature Reserve. The results indicated that the ECM fungal and soil bacterial diversity of CC and CF was similar, and the diversity rates of CC and CF were higher than those of PM, CE, and KC. Cenococcum geophilum and unclassified_Cortinariaceae II were the most prevalent occurring ECM fungi species in the five typical tree species, followed by unclassified_Cortinariaceae I and Lactarius atrofuscus. In bacteria, the dominant bacterial genera were Acidothermus, Bradyrhizobium, Acidibacter, Candidatus_Solibacter, Candidatus_Koribacter, Roseiarcus, and Bryobacter. EMF fungi and soil bacteria were correlated with edaphic factors, especially the soil pH, TP, and TK, caused by stand development. The results show that the community characteristics of ECM fungi and bacteria in the typical tree species of the Junzifeng National Nature Reserve reflect the critical role of soil microorganisms in stabilizing forest ecosystems.

Organomineral fertilizer application enhances Perilla frutescens nutritional quality and rhizosphere microbial community stability in karst mountain soils

Introduction

Applications of organomineral fertilizer (OMF) are important measures for developing organic agriculture in karst mountain areas. However, the influence of OMF on the structure and function of soil microbial diversity and their relationship with crop yield and quality are still unclear.

Methods

Based on soil science, crop science, and high-throughput sequencing methods, we investigated the changes of rhizosphere soil microbial communities of Perilla frutescens under different fertilization measures. Then, the relationship between P. frutescens yield and quality with soil quality was analyzed.

Results

The results showed that the addition of OMF increased the amount of total carbon and total potassium in soil. OF, especially OMF, improved P. frutescens yield and quality (e.g., panicle number per plant, main panicle length, and unsaturated fatty acid contents). Both OF and OMF treatments significantly increased the enrichment of beneficial microorganism (e.g., Bacillus, Actinomadura, Candidatus_Solibacter, Iamia, Pseudallescheria, and Cladorrhinum). The symbiotic network analysis demonstrated that OMF strengthened the connection among the soil microbial communities, and the community composition became more stable. Redundancy analysis and structural equation modeling showed that the soil pH, available phosphorus, and available potassium were significantly correlated with soil microbial community diversity and P. frutescens yield and quality.

Discussion

Our study confirmed that OMF could replace CF or common OF to improve soil fertility, crop yield and quality in karst mountain soils.