Arbuscular Mycorrhizal Fungi Species Research Articles

A symbiotic footprint in the plant root microbiome

BackgroundA major aim in plant microbiome research is determining the drivers of plant-associated microbial communities. While soil characteristics and host plant identity present key drivers of root microbiome composition, it is still unresolved whether the presence or absence of important plant root symbionts also determines overall microbiome composition. Arbuscular mycorrhizal fungi (AMF) and N-fixing rhizobia bacteria are widespread, beneficial root symbionts that significantly enhance plant nutrition, plant health, and root structure. Thus, we hypothesized that symbiont types define the root microbiome structure.ResultsWe grew 17 plant species from five families differing in their symbiotic associations (no symbioses, AMF only, rhizobia only, or AMF and rhizobia) in a greenhouse and used bacterial and fungal amplicon sequencing to characterize their root microbiomes. Although plant phylogeny and species identity were the most important factors determining root microbiome composition, we discovered that the type of symbioses also presented a significant driver of diversity and community composition. We found consistent responses of bacterial phyla, including members of the Acidobacteria, Chlamydiae, Firmicutes, and Verrucomicrobia, to the presence or absence of AMF and rhizobia and identified communities of OTUs specifically enriched in the different symbiotic groups. A total of 80, 75 and 57 bacterial OTUs were specific for plant species without symbiosis, plant species forming associations with AMF or plant species associating with both AMF and rhizobia, respectively. Similarly, 9, 14 and 4 fungal OTUs were specific for these plant symbiont groups. Importantly, these generic symbiosis footprints in microbial community composition were also apparent in absence of the primary symbionts.ConclusionOur results reveal that symbiotic associations of the host plant leaves an imprint on the wider root microbiome – which we term the symbiotype. These findings suggest the existence of a fundamental assembly principle of root microbiomes, dependent on the symbiotic associations of the host plant.

Biochemical characterization and mycorrhizal fungal community of plant species in the Brazilian seasonal dry forest.

Invasive alien plant species (IAPS) have the ability to change the biochemical properties and the arbuscular mycorrhizal fungal (AMF) community structure in their rhizosphere. Organic acids, microbial activity, and AMF play a key role in the invader's spread and also has interactions with the soil chemical factors. Our aim here was to assess the rhizosphere's biochemical factors, AMF community composition, and soil chemical properties associated with Cryptostegia madagascariensis (IAPS) and Mimosa tenuiflora (endemic plant species) from the Brazilian Seasonal Dry Forest. The highest values of total glomalin (5.87 mg g-1 soil), root colonization (54.5%), oxalic and malic acids (84.21 and 3.01 μmol g-1 , respectively), microbial biomass C (mg kg-1 ), Na+ (0.080 cmolc kg-1 ), Ca2+ (7.04 cmolc kg-1 ), and soil organic carbon (4.59 g kg-1 ) were found in the rhizosphere of C. madagascariensis. We found dissimilarities on AMF community structure considering the studied plant species: (i) Racocetra coralloidea, Dentiscutata heterogama, Dentiscutata cerradensis, Gigaspora decipiens, and AMF's richness were highly correlated with the rhizosphere of M. tenuiflora; and (ii). The rhizosphere of C. madagascariensis was highly correlated with the abundance of Claroideoglomus etunicatum, Rhizoglomus aggregatum, Funneliformis mosseae, and Funneliformis geosporum. The results of our study highlight the importance of considering C. madagascariensis as potential hosts for AMF species from Glomerales, and a potential plant species that increase the bioavailability of exchangeable Na and Ca at semi-arid conditions.

Lotus tenuis maintains high arbuscular mycorrhizal diversity in grasslands regardless of soil properties or management

This study aimed to evaluate the root colonization and diversity of arbuscular mycorrhizal fungi (AMF) associated with Lotus tenuis grown in natural and L. tenuis-promoted grasslands (by herbicide application, which consists in removing above-ground biomass to favor the establishment and growth of L. tenuis) in the Salado River Basin (Argentina). Soils ranged from saline and/or sodic to neutral and non-saline. AMF colonization was slightly higher in natural grasslands than in L. tenuis-promoted sites (93% and 86%, respectively). A total of 22 AMF species were identified in root-associated soil. The Glomeraceae was the only family present in all sites, and Funneliformis mosseae was the only species found in all the sites studied, regardless of the soil properties and management. Claroideoglomus etunicatum and Septoglomus constrictum were present in all sites except in one of the L. tenuis-promoted sites studied. The PCR-Single-Strand Conformation Polymorphism analysis showed that amplicons of AMF-Glomeraceae did not cluster in a site-specific or management-specific way. The sequences obtained were highly similar to sequences of Glomeraceae detected by morphological spore taxonomy. L. tenuis promotion by herbicide application did not negatively affect AMF colonization or diversity. L. tenuis contributed to maintaining AMF diversity through high root colonization, regardless of soil properties or management. This should be considered for the maintenance of L. tenuis and AMF-associated communities.

Recovering arbuscular mycorrhizal fungi (AMF) from decomposing litter: an unusual approach

ABSTRACT A few studies indicated a possible role of arbuscular mycorrhizal fungi (AMF) in leaf litter decomposition. Information about these fungi in leaf litter is limited by the availability of techniques to recover them from such substrates. In the present study we aimed to (i) test an alternative approach for AMF recovery from litter; (ii) investigate if the AMF community structure in leaf litter differs between plant species; (iii) assess whether glomoid spore type might be more abundant in litter and (iv) determine whether litter quality and soil chemical parameters influence AMF communities. Leaves and soil were collected in three areas in the Brazilian Atlantic Forest. AMF were obtained from the leaves using a moist chamber approach. AMF communities were evaluated for their species richness, abundance, and diversity. In addition, the influence of soil chemical properties and litter quality on the structure of AMF communities was evaluated. Thirteen AMF species representing the genera Acaulospora, Entrophospora, Diversispora, Gigaspora, and Glomus, were recovered from leaves. The highest richness was observed in Ziziphus joazeiro leaves at Fazenda Sapé, whereas the highest diversity was found in the leaves of Hymenaea courbaril at Flona. AMF communities were influenced by litter quality and the P content of the soil. Our data show that this alternative approach for recovering AMF from the litter was successful in detecting communities inhabiting tropical conditions. This pilot research is an essential attempt to address the gap of knowledge about the occurrence of AMF in leaf litter and delimit future strategies to assess their function in this substrate.

Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores.

Rhizophagus irregularis is the model species for arbuscular mycorrhizal fungi (AMF) research and the most widely propagated species for commercial plant biostimulants. Using asymbiotic and symbiotic cultivation systems initiated from single spores, advanced microscopy, Sanger sequencing of the glomalin gene, and PacBio sequencing of the partial 45S rRNA gene, we show that four strains of R. irregularis produce spores of two distinct morphotypes, one corresponding to the morphotype described in the R. irregularis protologue and the other having the phenotype of R. fasciculatus. The two spore morphs are easily distinguished by spore colour, thickness of the subtending hypha, thickness of the second wall layer, lamination of the innermost layer, and the dextrinoid reaction of the two outer spore wall layers to Melzer's reagent. The glomalin gene of the two spore morphs is identical and that of the PacBio sequences of the partial SSU-ITS-LSU region (2780 bp) obtained from single spores of the R. cf fasciculatus morphotype has a median pairwise similarity of 99.8% (SD = 0.005%) to the rDNA ribotypes of R. irregularis DAOM 197198. Based on these results, we conclude that the model AMF species R. irregularis is dimorphic, which has caused taxonomic confusion in culture collections and possibly in AMF research.

Effects of Bio- and Chemical Fertilizers on Growth and Soil Microbial Population of Cacao (Theobroma cacao L.) Seedlings

A comparative study was done to determine the growth, microbial population, and physico- chemical properties on UF18 cacao (Theobroma cacao) seedlings when treated with chemical fertilizers and biofertilizers, either applied singly or in combination. The experimental design was randomized completely block design with five seedlings per treatment per block. Treatments used were: control, ½ recommended rate of chemical (RRC) fertilizer, RRC, MYKORICH®, MYKOCAP®, ½ RRC + MYKORICH®, ½ RRC + MYKOCAP®, RRC + MYKORICH®, and RRC + MYKOCAP®. MYKORICH® and MYKOCAP® contain 12 species of arbuscular mycorrhizal fungi isolated from stressed environments. The results showed that plant growth and physico-chemical properties were significantly improved by the application of biofertilizer than by chemical fertilizer. MYKORICH® treatment gave the highest spore count and is highly significant (p < 0.05) as compared to the other treatments with spore count ranging from 41–115.5/ 50 g soil. In terms of nitrogen-fixing bacteria count, ½ RRC treatment gave the highest (16.9 CFU x 10–5 g soil–1) bacterial count. RRC + MYKORICH® inoculation gave the highest values for most of the soil physico-chemical analysis (pH, P, K, and CEC). The positive response of cacao seedlings to mycorrhizal inoculation with or without chemical fertilizer provides a useful criterion in other agricultural lands throughout the country for crop production and sustainability.

Impact of long-term application of paclobutrazol in communities of arbuscular mycorrhizal fungi and their efficiency in the development of Helianthus annuus L.

Paclobutrazol (PBZ) is a phytoregulator known for inhibiting plant vegetative growth and promoting flowering in mango crop (Mangifera indica L.). PBZ belongs to the triazole family, a group recognized by its fungicide capacity, and its application to the soil can directly influence microbial communities, however, little is known about its effects on arbuscular mycorrhizal fungi (AMF). The objectives of this work were to evaluate the impact of long-term application of PBZ on the AMF communities and to verify whether the management time affects the functionality of these communities in promoting the development of ornamental sunflower Helianthus annuus L. (var. Dwarf Double Sungold). Sampling was carried out in mango cultivation areas with a history of PBZ application that varied from no application to application for up to 15 years. For the analysis of the AMF community, the quantification of most probable number (MPN) of infective AMF propagules, abundance of glomerospores, richness, diversity, Simpson dominance, and Pielou's evenness were evaluated. The analysis of the functionality of the AMF community was based on the analysis of the variables of growth and mycorrhizal colonization. Soils with a prolonged history of PBZ application (>nine years) presented distinct AMF communities with lower abundance of glomerospores in relation to areas without PBZ application and with native Caatinga vegetation. However, the soil-inoculum of this AMF community has greater efficiency in promoting sunflower development and mycorrhizal colonization, suggesting greater functionality. It is concluded that the time of application and performance of PBZ in the soil influence the composition of the AMF community. Even with reduction of richness and diversity of AMF species in soils with a prolonged history of PBZ application, there are functional AMF communities in these soils that promoted sunflower plant growth, selecting more efficient and resistant species.

Identification of Arbuscular Mycorrhizal Fungi associated with Arabica coffee root (Coffea arabica) in the Arfak Mountains region of West Papua, Indonesia

Abstract. Suparno A, Prabawardani S, Nisa DK, Ruimassa RR. 2023. Identification of Arbuscular Mycorrhizal Fungi associated with Arabica coffee root (Coffea arabica) in the Arfak Mountains region of West Papua, Indonesia. Biodiversitas 24: 3207-3213. Coffee is a global commodity widely consumed as a beverage globally and has a high economy. Currently, the trend of drinking coffee is no longer dominated by older people but has become part of the millennial and celebrity lifestyle; therefore, worldwide demand for coffee continues to increase. Efforts to develop area expansion and productivity continue to be pursued. The Arfak Mountains Region of West Papua, located 800 - 2,500 m above sea level (masl), is a potential area for coffee plantations. The local farmers in this area have grown coffee independently and with gradual government support for the last years. Given the benefits of Arbuscular Mycorrhizal Fungi (AMF), which can increase plant growth and productivity, this study aims to identify the types of AMF that are associated with coffee plants in 4 districts, Mokwam, Anggi Giji, Anggi Gida, and Membey in Arfak Mountains region, West Papua. Identification of AMF types was observed based on the morphology of mycorrhizal spores. The research was conducted using the observation method with a purposive sampling technique from November 2022 to March 2023. Based on the observation, the coffee plants in 4 districts were associated with AMF. The types of AMF associated with coffee in Mokwam were more numerous than in other locations, namely the Acaulosporaceae Genus with five species, Glomeaceae Genus with five species, one species of Simiglomus sensu stricto, one species of Funneliformis sensu stricto, and one species of Septoglomus sensu stricto. AMF in Anggi Giji District consisted of Acaulosporaceae Genus with two species, Glomeaceae Genus with four species, while in Anggi Gida District consisted of Acaulosporaceae Genus with one species, Glomeaceae Genus with three species, one species Septoglomus sensu stricto. AMF species in the coffee plants of the Membey District are the Acaulosporaceae Genus with three species, the Glomeaceae Genus with two species, and one species of Septoglomus sensu stricto. From the soil analysis results, the soil fertility level is low; conversely, the mycorrhizal presence level is higher because of the more infertile soil, the more active mycorrhiza.

Association of mycoheterotrophic Gentianaceae with specific Glomus lineages.

Some plant species took an alternative evolutionary pathway in which they lost their photosynthetic capacity to depend exclusively on carbon supplied by arbuscular mycorrhizal fungi (AMF) in an association called mycoheterotrophy. Among them is Voyriella parviflora, a species of the family Gentianaceae, which is found in tropical regions such as the Amazon basin. Here, we assessed the identity of AMF symbionts associated with this species. DNA was isolated from eight Gentianaceae specimens and from litter and surrounding roots of photosynthetic plants. The atp1 gene was amplified by Sanger sequencing to determine the taxonomic affiliation of the mycoheterotrophic plants. A 280bp region of the 18S rRNA gene of AMF was amplified with primers NS31/AML2 by high-throughput sequencing. The mycoheterotrophic specimens were assigned to V. parviflora with a bootstrap support of 72%. Glomus was the most abundant AMF genus, both in the mycoheterotrophic plants and in the litter and roots of photosynthetic plants. In addition, a few Glomus genotypes were abundantly enriched in the mycoheterotrophic plants, with only a few specimens colonized by Gigaspora, Acaulospora, and Scutellospora in a low proportion. These genotypes formed a cluster within a larger clade, suggesting that V. parviflora shows a preferential association with a narrow Glomus lineage which is not phylogenetically close to a previously identified V. parviflora's associated lineage. Furthermore, detecting fungi from other families suggests that V. parviflora is colonized by other genera, although with low frequency. These findings provide new insights into the association between AMF and mycoheterotrophic species and highlight the importance of considering trap culture-independent approaches in understanding this symbiosis.

Test the viability and effectiveness of the AMF biofertilizer prototypes using different spore carrier media on production of organic cocoa

Increasing consumer demand for healthy food products has an impact on increasing demand for organic cocoa, but it is difficult for farmers to fulfil it because the production per hectare is still very low. Development of indigenous Arbuscular Mycorrhizal Fungi (AMF) as biological fertilizers is expected to relieve farmers’ difficulties. This study aimed to find the best AMF biofertilizer prototype that can increase organic cocoa production while increasing soil fertility. The research was conducted through 2 stages. Stage 1 made prototypes of biological fertilizers from 7 indigenous AMF species isolated from cocoa roots using different spore carrier media and then tested the spore viability during storage, and stage 2 selected 2 of the best AMF biofertilizer prototypes to test their effectiveness on organic cocoa plantations. The results showed the AMF biofertilizer prototype with spore’s carrier media volcanic sand and zeolite gave the viability of spores remained high after being stored for 1 month, reaching 91.78% and 90.67%. The effectiveness test on organic cocoa plantations showed that the AMF biofertilizer prototype with different spore-carrying media had no significant effect on the yield and yield components of organic cocoa beans, but AMF biofertilizer prototype with volcanic sand spore-carrying media tended to increase the yield and improves soil fertility. It was concluded that the AMF biofertilizer prototype with volcanic sand spore carrier media was the best prototype, but it is necessary to carry out tests at several locations to determine the consistency of the effect.

Characterization of the arbuscular mycorrhizal fungal community associated with rosewood in threatened Miombo forests.

Understanding the dynamics of arbuscular mycorrhizal fungi (AMF) in response to land use change is important for the restoration of degraded forests. Here, we investigated the AMF community composition in the roots of Pterocarpus tinctorius sampled from agricultural and forest fallow soils rich in aluminum and iron. By sequencing the large subunit region of the rRNA gene, we identified a total of 30 operational taxonomic units (OTUs) in 33 root samples. These OTUs belonged to the genera Rhizophagus, Dominikia, Glomus, Sclerocystis, and Scutellospora. The majority of these OTUs did not closely match any known AMF species. We found that AMF species richness was significantly influenced by soil properties and overall tree density. Acidic soils with high levels of aluminum and iron had a low mean AMF species richness of 3.2. Indicator species analyses revealed several AMF OTUs associated with base saturation (4 OTUs), high aluminum (3 OTUs), and iron (2 OTUs). OTUs positively correlated with acidity (1 OTU), iron, and available phosphorus (2 OTUs) were assigned to the genus Rhizophagus, suggesting their tolerance to aluminum and iron. The results highlight the potential of leguminous trees in tropical dry forests as a reservoir of unknown AMF species. The baseline data obtained in this study opens new avenues for future studies, including the use of indigenous AMF-based biofertilizers to implement ecological revegetation strategies and improve land use.

A module centered on the transcription factor Msn2 from arbuscular mycorrhizal fungus Rhizophagus irregularis regulates drought stress tolerance in the host plant.

Arbuscular mycorrhizal (AM) fungi can form mutualistic endosymbiosis with > 70% of land plants for obtaining fatty acids and sugars, in return, AM fungi promote plant nutrients and water acquisition to enhance plant fitness. However, how AM fungi orchestrate its own signaling components in response to drought stress remains elusive. Here, we identify a transcription factor containing C2H2 zinc finger domains, RiMsn2 from Rhizophagus irregularis. To characterize the RiMsn2, we combined heterologous expression, subcellular localization in yeasts, and biochemical and molecular studies with reverse genetics approaches during the in planta phase. The results indicate that RiMsn2 is highly conserved across AM fungal species and induced during the early stages of symbiosis. It is significantly upregulated in mycorrhizal roots under severe drought conditions. The nucleus-localized RiMsn2 regulates osmotic homeostasis and trehalose contents of yeasts. Importantly, gene silencing analyses indicate that RiMsn2 is essential for arbuscule formation and enhances plant tolerance to drought stress. Results from yeasts and biochemical experiments suggest that the RiHog1-RiMsn2-STREs module controls the drought stress-responsive genes in AM fungal symbiont. In conclusion, our findings reveal that a module centered on the transcriptional activator RiMsn2 from AM fungus regulates drought stress tolerance in host plant.

Effects of Arbuscular Mycorrhizal Fungi on Robinia pseudoacacia L. Growing on Soils Contaminated with Heavy Metals.

Arbuscular mycorrhizal fungi (AMF) have been shown to assist plants in increasing metal tolerance and accumulation in heavy metal (HM)-contaminated soils. Herein, a greenhouse pot experiment was conducted to assess the interactions of growth substrates (S1, S2, and S3, respectively) with various HM contamination and nutrient status sampling from a typical contaminated soil and tailings in Shuikoushan lead/zinc mining in Hunan province, China, and AMF inoculation obtained from plants in uncontaminated areas (Glomus mosseae, Glomus intraradices, and uninoculated, respectively) on the biomass and uptake of HMs and phosphorus (P) by the black locust plant (Robinia pseudoacacia L.). The results indicated that the inoculation with AMF significantly enhanced the mycorrhizal colonization of plant roots compared with the uninoculated treatments, and the colonization rates were found to be higher in S1 and S2 compared with S3, which were characterized with a higher nutrient availability and lead concentration. The biomass and heights of R. pseudoacacia were significantly increased by AMF inoculation in S1 and S2. Furthermore, AMF significantly increased the HM concentrations of the roots in S1 and S2 but decreased the HM concentrations in S3. Shoot HM concentrations varied in response to different AMF species and substrate types. Mycorrhizal colonization was found to be highly correlated with plant P concentrations and biomass in S1 and S2, but not in S3. Moreover, plant biomass was also significantly correlated with plant P concentrations in S1 and S2. Overall, these findings demonstrate the interactions of AMF inoculation and growth substrates on the phytoremediation potential of R. pseudoacacia and highlights the need to select optimal AMF isolates for their use in specific substrates for the remediation of HM-contaminated soil.

Effects of AMF inoculation on the eco-physiological characteristics of Imperata cylindrica under differing soil nitrogen conditions.

Arbuscular mycorrhizal fungi (AMF) play a key role in terrestrial ecosystems, while the ecological restoration application of AMF in mining areas has been progressively gaining attention. This study simulated a low nitrogen (N) environment in copper tailings mining soil to explore inoculative effects of four AMF species on the eco-physiological characteristics of Imperata cylindrica, and provided plant-microbial symbiote with excellent resistance to copper tailings. Results show that N, soil type, AMF species, and associated interactions significantly affected ammonium (), nitrate nitrogen (), and total nitrogen (TN) content and photosynthetic characteristics of I. cylindrica. Additionally, interactions between soil type and AMF species significantly affected the biomass, plant height, and tiller number of I. cylindrica. Rhizophagus irregularis and Glomus claroideun significantly increased TN and content in the belowground components I. cylindrica in non-mineralized sand. Moreover, the inoculation of these two fungi species significantly increased belowground content in mineralized sand. The net photosynthetic rate positively correlated to aboveground total carbon (TC) and TN content under the high N and non-mineralized sand treatment. Moreover, Glomus claroideun and Glomus etunicatum inoculation significantly increased both net photosynthetic and water utilization rates, while F. mosseae inoculation significantly increased the transpiration rate under the low N treatment. Additionally, aboveground total sulfur (TS) content positively correlated to the intercellular carbon dioxide (CO2) concentration, stomatal conductance, and the transpiration rate under the low N sand treatment. Furthermore, G. claroideun, G. etunicatum, and F. mosseae inoculation significantly increased aboveground and belowground TC content of I. cylindrica, while G. etunicatum significantly increased belowground content. Average membership function values of all physiological and ecological I. cylindrica indexes infected with AMF species were higher compared to the control group, while corresponding values of I. cylindrica inoculated with G. claroideun were highest overall. Finally, comprehensive evaluation coefficients were highest under both the low N and high N mineralized sand treatments. This study provides information on microbial resources and plant-microbe symbionts in a copper tailings area, while aiming to improve current nutrient-poor soil conditions and ecological restoration efficiency in copper tailings areas.

Arbuscular Mycorrhizal Fungi as an Important Factor Enabling the Adaptation of Anthyllis vulneraria L. to Zn-Pb-Polluted Tailings.

The old Zn-Pb-contaminated (calamine) tailings in southern Poland are spontaneously colonized by metal-tolerant Anthyllis vulneraria L. (Fabaceae), which can form simultaneously symbiotic association with nitrogen-fixing rhizobia and phosphorus-acquiring arbuscular mycorrhizal fungi (AMF). So far, fungal colonization and the AMF diversity of calamine-inhabiting legumes have been poorly studied. Thus, we determined AMF spore density in the substratum and the mycorrhizal status of nodulated A. vulneraria plants occurring on calamine tailings (M) and on a reference non-metallicolous (NM) site. The results indicate the presence of the Arum-type of arbuscular mycorrhiza in the roots of both Anthyllis ecotypes. Despite the presence of AM fungi in M plant roots, the dark septate endophyte (DSE) fungi (hyphae and microsclerotia) were occasionally also detected. Metal ions were accumulated mainly in the nodules and intraradical fungal structures rather than thick plant cell walls. Mycorrhization parameters (frequency of mycorrhization and intensity of root cortex colonization) for M plants were markedly higher and differed in a statistically significant manner from the parameters for NM plants. Heavy metal excess had no negative effect on the number of AMF spores, the amounts of glomalin-related soil proteins and AMF species composition. Molecular identification of AMF using PCR-DGGE analysis based on the 18S rDNA ribosomal gene by nested-PCR with primers AM1/NS31 and NS31-GC/Glo1 revealed similar genera/species of AMF in the roots of both Anthyllis ecotypes: Rhizophagus sp., R. fasciculatus, and R. iranicus. The results of this work indicate the presence of unique fungal symbionts, which may enhance A. vulneraria tolerance to heavy metal stress and plant adaptation to extreme conditions on calamine tailings.

Arbuscular mycorrhizae influence raspberry growth and soil fertility under conventional and organic fertilization.

Introducing beneficial soil biota such as arbuscular mycorrhizal fungi (AMF) to agricultural systems may improve plant performance and soil fertility. However, whether bioinocula species composition affects plant growth and soil fertility, and whether fertilizer source influences AMF colonization have not been well characterized. The objectives of this research were to: (1) assess if AMF bioinocula of different species compositions improve raspberry (Rubus idaeus L.) performance and characteristics of soil fertility and (2) evaluate the impact of fertilizer source on AMF colonization. Five bioinocula with different AMF species compositions and three fertilizer sources were applied to tissue culture raspberry transplants in a randomized complete block design with eight replicates. Plants were grown in a greenhouse for 14 weeks and plant growth, tissue nutrient concentrations, soil fertility, and AMF root colonization were measured. Shoot K and Zn concentrations as well as soil pH and K concentration increased in the Commercial Mix 1 treatment (Glomus, Gigaspora, and Paraglomus AMF species) compared to the non-inoculated control. RFI (raspberry field bioinoculum; uncharacterized AMF and other microbiota) increased soil organic matter (SOM), estimated nitrogen release (ENR), and soil copper (Cu) concentration compared to the non-inoculated control. Furthermore, plants receiving the Mix 1 or RFI treatments, which include more AMF species, had greater AMF root colonization than the remaining treatments. Plants receiving organic fertilizer had significantly greater AMF colonization than conventionally fertilized plants. Taken together, our data indicate that coupling organic fertilizers and bioinocula that include diverse AMF species may enhance raspberry growth and soil fertility.

Suppression of Sclerotium rolfsii and Fusarium oxysporum through Glomalin a Glycoprotein Produced by Arbuscular Mycorrhizal Fungi under in vitro Condition

For sustainable agriculture to succeed, especially in the production of organic food, the use of biofertilizers and biopesticides is essential. Arbuscular mycorrhizal symbiosis is important for improving plant development through increased nutrient intake, soil stabilization, and carbon sequestration through the creation of glomalin, a distinct and specialized protein. It was not determined whether glomalin affects soil-borne fungi infections. Therefore, using glomalin isolated from the soil used to raise maize plants inoculated with various arbuscular mycorrhizal fungi (AMF), the inhibition of soil-borne plant diseases Sclerotium rolfsii and Fusarium oxysporum was examined. The outcomes demonstrated that there was variation in the quantity of glomalin generated by various AMF species. Glomalin isolated from soil inoculated with Glomus coronatum suppressed Sclerotium rolfsii and Fusarium oxysporum more effectively in in-vitro tests than soil inoculated with Glomus intraradices and Glomus mosseae.

Arbuscular mycorrhizal fungi trigger danger-associated peptide signaling and inhibit carbon-phosphorus exchange with nonhost plants.

In soil, arbuscular mycorrhizal fungi (AMF) meet the roots of both host and presumed nonhost plants, but the interactional mechanisms of AMF with and functional relevance for nonhost plants is little known. Here we show AMF can colonize an individually grown nonhost plant, Arabidopsis thaliana, and suppress the growth of Arabidopsis and two nonhost Brassica crops. This inhibitory effect increased with increasing AMF inoculum density, and was independent of AMF species or nutrient availability. 13 C isotope labeling and physiological analyses revealed no significant carbon-phosphorus exchange between Arabidopsis and AMF, indicating a lack of nutritional function in this interaction. AMF colonization activated the danger-associated peptide Pep-PEPR signaling pathway, and caused clear defense responses in Arabidopsis. The impairment of Pep-PEPR signaling in nonhost plants greatly compromised AMF-triggered defensive responses and photosynthesis suppression, leading to higher colonization rates and reduced growth suppression upon AMF inoculation. Pretreatment with Pep peptide decreased AMF colonization, and largely substituted for AMF-induced growth suppression in nonhosts, confirming that the Pep-PEPR pathway is a key participant in resistance to AMF colonization and in mediating growth suppression of nonhost plants. This work greatly increases our knowledge about the functional relevance of AMF and their mechanisms of interactions with nonhost plants.

Asymbiotic Spore Production of Rhizoglomus intraradices in a Medium Containing Myristate

This study examined the effects of myristate on an asymbiotic culture of Rhizoglomus intraradices, a species of arbuscular mycorrhizal fungi (AMF; Glomeromycota). Mycelial growth and sporulation in a modified medium containing myristate were observed. The findings demonstrated that myristate induced R. intraradices spore formation, with daughter spores having a smaller diameter than the parent spores. This observation is consistent with previous studies on other Rhizoglomus species. Further studies are needed to investigate the potential for continuous culture, mass production using daughter spores, and the application of AMF colonization techniques in plants.

Hongos micorrízicos y fertilización fosfatada en la preparación de plántulas de porta-injertos de vid ‘IAC-766’ Campinas

Arbuscular mycorrhizal fungi (AMF) are beneficial microorganisms that form symbioses with vines, showing improvements favorably in the growth and nutrition of seedlings after rooting them. This work aimed to evaluate the effects of AMF species inoculation and phosphate fertilization on rooted cuttings of vine rootstocks in a greenhouse. Woody rootstock cuttings from 'IAC 766' Campinas vines were prepared to promote rooting. After 45 days, the cuttings were transplanted and subjected to treatments that consisted of the inoculation of different species of AMF and fertilization with two doses of phosphorus (simple superphosphate) plus the control. The treatments were randomly assigned following a completely randomized design with eight replications for each treatment. After 90 days, growth parameters, macro and micronutrient content (shoot and root), root colonization and mycorrhizal effect of the extracted nutrients were evaluated. The inoculation with AMF species influenced the growth parameters, root colonization and extraction of macro and micronutrients from the cuttings of the 'IAC 766' rootstock, highlighting the inoculation with species of the genus Acaulospora, either individually or associated. Phosphorous fertilization affected growth parameters and extraction of macro and micronutrients, but these were to a lesser degree compared to that verified by the inoculation of AMF species.