Arbuscular Mycorrhizal Research Articles

Mycorrhizal fungi as critical biotic filters for tree seedling establishment during species range expansions

AbstractGlobal warming has been shifting climatic envelopes of many tree species to higher latitudes and elevations across the globe; however, unsuitable soil biota may inhibit tree migrations into these areas of suitable climate. Specifically, the role of mycorrhizal fungi in facilitating tree seedling establishment beyond natural species range limits has not been fully explored within forest ecosystems. We used three experiments to isolate and quantify the effects of mycorrhizal colonization and common mycorrhizal networks (CMN) on tree seedling survival and growth across (within and beyond) the elevational ranges of two dominant tree species in northeastern North America, which were associated with either arbuscular mycorrhiza (AMF, Acer saccharum) or ectomycorrhiza (EMF, Fagus grandifolia). In order to quantify the influence of mycorrhiza on seedling establishment independent of soil chemistry and climate, we grew seedlings in soils from within and beyond our study species ranges in a greenhouse experiment (GE) as well as in the field using a soil translocation experiment (STE) and another field experiment manipulating seedling connections to potential CMNs (CMNE). Root length colonized, seedling survival and growth, foliar nutrients, and the presence of potential root pathogens were examined as metrics influencing plant performance across species' ranges. Mycorrhizal inoculum from within species ranges, but not from outside, increased seedling survival and growth in a greenhouse setting; however, only seedling survival, and not growth, was significantly improved in field studies. Sustained potential connectivity to AMF networks increased seedling survival across the entire elevational range of A. saccharum. Although seedlings disconnected from a potential CMN did not suffer decreased foliar nutrient levels compared with connected seedlings, disconnected AM seedlings, but not EM seedlings, had significantly higher aluminum concentrations and more potential pathogens present. Our results indicate that mycorrhizal fungi may facilitate tree seedling establishment beyond species range boundaries in this forested ecosystem and that the magnitude of this effect is modulated by the dominant mycorrhizal type present (i.e., AM vs. EM). Thus, despite changing climate conditions beyond species ranges, a lack of suitable mutualists can still limit successful seedling establishment and stall adaptive climate‐induced shifts in tree species distributions.

Symbiotic conserved arbuscular mycorrhiza fungi supports plant health

Arbuscular mycorrhiza fungi (AMF) forms a multi-beneficial symbiotic relationship with the host plant, therefore it is considered to be an effective helper to promote plant health. However, failure to consider the source or universality of AMF is often unstable during application. Therefore, it is necessary to screen potential AMF inoculants based on the source and the relationship with host. In search of more effective and broad-spectrum AMF inoculants, we studied AMF community structure properties of healthy and diseased plants in 24 fields from four sampling sites. The results indicated that the environmental filtering effect of roots was obvious, which was manifested as a decrease of α-diversity from rhizosphere to root. Differences in α-diversity between healthy and diseased roots further indicate the importance of AMF communities within roots for maintaining plant health. Glomus is significantly enriched and dominant in healthy roots, independent of environment and phylogenically conserved. Spores were further isolated and evaluated for their disease-preventing and pro-growth properties. Based on whether they were symbiotic with plant and root-enrichment characteristics, isolated AMF spores were classified as symbiotic conserved, symbiotic non-conserved, and non-symbiotic AMF. After spores were propagated and inoculated to plant roots, only symbiotic conserved AMF significantly promoted plant growth and maintained health, highlighting the potential of symbiotic conserved AMF in sustainable plant production.

Globally Distributed Arbuscular Mycorrhizal Fungi Associated With Invasive Cinchona pubescens on Santa Cruz Island, Galápagos.

The presence of arbuscular mycorrhizal fungi (AMF) is essential for the survival and establishment of most plant species in nature. The reproductive success of invasive plant species in a particular habitat could also depend on these AM fungi. Cinchona pubescens, commonly known as quinine, is highly invasive on Santa Cruz Island, Galápagos, but at the same time severely endangered in its native range on mainland Ecuador due to overexploitation in the past. In this study, we aim at determining the AMF communities associated with C. pubescens at both locations to investigate whether the successful invasion of C. pubescens on Santa Cruz is related to its association with a particular community of AMF. For this, roots of C. pubescens trees were sampled at three sites, one site on Santa Cruz and two sites in the province of Loja, on mainland Ecuador. Communities of AM fungi were determined through the molecular cloning and sequencing of the 18S nrDNA gene and through the delimitation of Operational Taxonomic Units (OTUs), associated with the plant roots. We found 36 AMF OTUs associated with C. pubescens, most of them belonging to the genus Glomus. The highest richness of AMF OTUs was detected in samples from sites located on mainland Ecuador. The AMF communities between Santa Cruz and mainland Ecuador were significantly different, and only five OTUs were shared between both locations. Two dominant OTUs in C. pubescens from Santa Cruz were detected but no dominant OTUs from mainland Ecuador. Almost two thirds of the OTUs associated with C. pubescens had a wide global distribution. Our results suggest that the successful invasion of C. pubescens on Santa Cruz could have been facilitated by local generalist AMF and not by particular AMF. The observed generalist AMF from both locations could be important for conservation plans of restoring the endangered C. pubescens in the native forests on mainland Ecuador.

Tripartite interactions between grapevine, viruses, and arbuscular mycorrhizal fungi provide insights into modulation of oxidative stress responses

Arbuscular mycorrhizal fungi (AMF) can be beneficial for plants exposed to abiotic and biotic stressors. Although widely present in agroecosystems, AMF influence on crop responses to virus infection is underexplored, particularly in woody plant species such as grapevine. Here, a two-year greenhouse experiment was set up to test the hypothesis that AMF alleviate virus-induced oxidative stress in grapevine. The ‘Merlot’ cultivar was infected with three grapevine-associated viruses and subsequently colonized with two AMF inocula, containing one or three species, respectively. Five and fifteen months after AMF inoculation, lipid peroxidation - LPO as an indicator of oxidative stress and indicators of antioxidative response (proline, ascorbate - AsA, superoxide dismutase - SOD, ascorbate- APX and guaiacol peroxidases - GPOD, polyphenol oxidase - PPO, glutathione reductase - GR) were analysed. Expression of genes coding for a stilbene synthase (STS1), an enhanced disease susceptibility (EDS1) and a lipoxygenase (LOX) were determined in the second harvesting. AMF induced reduction of AsA and SOD over both years, which, combined with not AMF-triggered APX and GR, suggests decreased activation of the ascorbate-glutathione cycle. In the mature phase of the AM symbiosis establishment GPOD emerged as an important mechanism for scavenging H2O2 accumulation. These results, together with reduction in STS1 and increase in EDS1 gene expression, suggest more efficient reactive oxygen species scavenging in plants inoculated with AMF. Composition of AMF inocula was important for proline accumulation. Overall, our study improves the knowledge on ubiquitous grapevine-virus-AMF systems in the field, highlighting that established functional AM symbiosis could reduce virus-induced stress.

Synergism or Antagonism: Do Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria Work Together to Benefit Plants?

In agriculture, abiotic and biotic stress reduce yield by 51–82% and 10–16%, respectively. Applications of biological agents such as plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) can improve plant growth. Applications of lone PGPR and AMF also help plants resist abiotic and biotic stressors. The reports for dual inoculation of AMF and PGPR to benefit plants and tackle stressors are largely unknown. It is speculated that PGPR colonization in plants enhances AMF infection during dual AMF and PGPR application, although increased AMF colonization does not always correlate with the increased benefits for the plant hosts. Further research is needed regarding molecular mechanisms of communication during dual inoculations, and dual-inoculation enhancement of induced systemic resistance under pathogen stress, to understand how dual inoculations can result in enhanced plant benefits. The influence of application timing of AMF and PGPR dual inoculations on mitigating abiotic and biotic stress is also not well understood. This review documents the factors that govern and modulate the dual application of AMF and PGPR for plant benefits against stress responses, specifically abiotic (drought) stress and stress from pathogen infection.

Enhancement of PFAS stress tolerance and wastewater treatment efficiency by arbuscular mycorrhizal fungi in constructed wetlands

This study aims to explore the effects of arbuscular mycorrhizal fungi (AMF) on the growth of Iris pseudacorus L. and treatment efficacy in constructed wetlands (CWs) subjected to stress from per-and poly-fluoroalkyl substances (PFASs). The findings reveal that PFASs exposure induces oxidative damage and inhibits the growth of I. pseudacorus. However, AMF symbiosis enhances plant tolerance to PFAS stress by modulating oxidative responses. AMF treatment not only promoted plant growth but also improved photosynthetic efficiency under PFAS exposure. Compared to non-AMF treatment, those with AMF treatment exhibited significantly increased levels of peroxidases and antioxidant enzymes, including peroxidase and superoxide dismutase, along with a notable reduction in lipid peroxidation. Additionally, AM symbiosis markedly enhanced the efficacy of CWs in the remediation of wastewater under PFASs-induced stress, with removal efficiencies for COD, TP, TN, and NH4+-N increasing by 19–34%, 67–180%, 106–137%, and 25–95%, respectively, compared to the AMF- treatments. In addition, the metabolic pathways of PFASs appeared to be influenced by their carbon chain length, with long-chain PFASs like perfluorooctanoic acid (PFOA) and perfluoro anionic acid (PFNA) exhibiting more complex pathways compared to short-chain PFASs such as perfluoro acetic acid (PFPeA), and perfluoro hexanoic acid (PFHpA). These results suggest that AMF-plant symbiosis can enhance plant resilience against PFAS-induced stress and improve the pollutant removal efficiency of CWs. This study highlights the significant potential of AMF in enhancing environmental remediation strategies, providing new insights for the more effective management of PFAS-contaminated ecosystems.

Growth and physiology responses of Samanea saman inoculated with arbuscular mycorrhizal fungi in silica post-mining soil media using biodegradable pots

Arbuscular mycorrhizal fungi (AMF) and biodegradable pots are environmentally friendly and enhance plant growth in adverse soil conditions. These studies explored AMF interactions and biodegradable pots in physiology, growth, and the uptake of nutrients in Samanea saman seedlings. The present research interactive effects of biodegradable pots with different compositions and raw material sizes with and without AMF inoculation on S. saman grown in silica post-mining soil media. Results indicated AMF inoculations significantly improved leaf chlorophyll content, photosynthetic rate, heights, diameters, biomass, as well as nutrient absorption of S. saman as compared with non-inoculated plants in biodegradable pots. AMF and biodegradable pots composed of 15% used newspaper, 70% compost, 5% cocopeat, and 10% rock phosphate showed the best results and increased the leaf chlorophyll content, photosynthesis rate, height, diameter, and total biomass of the plants by 161.1%, 208.7%, 263.6%, 118.1%, and 269.9%, respectively, compared to biodegradable pots composed only of used newspaper. Additionally, uptake of the nutrients nitrogen, phosphate, potassium, and magnesium increased by 365%, 800%, 369%, and 250%, respectively. By the fourteenth week after transplanting, the C/N ratio of the organic pot decreased significantly. Thus, AMF and biodegradable pots containing compost and rock phosphate interact positively and enhance the growth of S. saman under adverse soil conditions. These findings suggest that biodegradable pots containing compost and rock phosphate show potential as more environmentally friendly replacements for plastic bags (polybags) as growth medium containers for seedling production.

Optimizing mycorrhizal fungi application for improved nutrient uptake, growth, and disease resistance in cardamom seedlings (Elettaria cardamomum (L.) Maton)

This study evaluated the impact of various doses (5, 10, 15 g) and application sequences (1, 2, or 3 times at monthly intervals) of arbuscular mycorrhizal (AM) fungal inoculum on cardamom seedlings over two years (2020–2021 and 2021–2022). The results indicated that the dosage of AM inoculum had a more substantial effect on the seedlings than the application sequence. A 10 g dose significantly increased shoot length and dry weight, while three applications of 5 g each improved the number of fibrous roots. Although potassium uptake was not affected, phosphorus and calcium uptake were highest with the 10 g dose. Arbuscular mycorrhizal inoculation also enhanced phosphatase activity in the rhizosphere, with 5 g improving acid phosphatase and 10 g improving alkaline phosphatase activity. Disease incidence, including seedling rot was lower with the 10 g dose, and additional sequential applications did not further reduce disease. Structural equation modeling (SEM) revealed that AM colonization positively influenced dry weight through the number of fibrous roots, showing a strong relationship between AM dose, colonization, spore count, and mycorrhizal dependency. This study indicates that applying a 10 g dose of AM fungal inoculum can be particularly beneficial in agroecosystems for improving cardamom seedling growth, nutrient uptake, and disease resistance.

Mycorrhizal Types Regulate Tree Spatial Associations in Temperate Forests: Ectomycorrhizal Trees Might Favour Species Coexistence.

In temperate mixed forests, dominant ectomycorrhizal (EM) tree species usually coexist with diverse arbuscular mycorrhizal (AM) understorey tree species. Here, we investigated the spatial associations between AM and EM trees in two > 20 ha temperate forest mega-plots to better understand the observed 'EM-dominant versus AM-diverse' coexistence. Overall, we found that positive spatial associations (e.g., facilitation) were mostly related to EM trees, while negative spatial associations (e.g., inhibition) were mainly related to AM trees. Because adult EM trees tended to facilitate surrounding AM and EM saplings and other EM adults in these two forests, facilitation hotspots that stabilize AM-EM tree coexistence should be centred around EM tree species rather than around AM tree species. Together, we propose a novel EM-stabilization mechanism, which emphasises how, despite some species-specific variation, EM tree species foster 'EM-dominant versus AM-diverse' coexistence in temperate mixed forests by facilitating other trees.

Mycorrhizal types determined the response of yield of woody bioenergy crops to environmental factors.

Meeting the demand for energy solely through fossil fuels has posed challenges. To mitigate the risk of energy shortage, woody bioenergy crops as a renewable energy feedstock have been the subject of many researchers. Also, mycorrhizas play an important role in crop productivity and inevitably affect the biomass yield of woody bioenergy crops. Based on a global synthesis of biomass yield of woody bioenergy crops, a framework for identifying and comparing bioenergy crop biomass in response to mycorrhizal type was developed. Our results found that the biomass yield of woody bioenergy crops in descending order was ectomycorrhizas (ECM) crops (10.2 ton DM ha-1year-1) > arbuscular mycorrhizas (AM)+ECM crops (8.8 ton DM ha-1year-1) > AM crops (8.0 ton DM ha-1year-1). In addition, our analysis revealed that the climate had the strongest effect on biomass yield in AM and ECM crops, whereas geography exerted the most significant influence on biomass yield in AM+ECM crops. Furthermore, there were differences in the biomass yield response of different mycorrhizal and plant types to geographic (latitude and elevation) and climatic factors (mean annual temperature (MAT) and mean annual precipitation (MAP)). When cultivating AM crops, we can focus more on temperature conditions-warmer locations, whereas for ECM crops, selecting regions with higher precipitation levels is advantageous. This study revealed the relationship between mycorrhizae and bioenergy crops. It provides data and theoretical support to rationalize differences in different woody bioenergy crops and their different responses to global change and increased production of bioenergy crops.

The biology and chemistry of a mutualism between a soil bacterium and a mycorrhizal fungus.

Arbuscular mycorrhizal (AM) fungi (e.g., Rhizophagus species) recruit specific bacterial species in their hyphosphere. However, the chemical interplay and the mutual benefit of this intricate partnership have not been investigated yet, especially as it involves bacteria known as strong producers of antifungal compounds such as Bacillus velezensis. Here, we show that the soil-dwelling B.velezensis migrates along the hyphal network of the AM fungus R.irregularis, forming biofilms and inducing cytoplasmic flow in the AM fungus that contributes to host plant root colonization by the bacterium. During hyphosphere colonization, R.irregularis modulates the biosynthesis of specialized metabolites in B.velezensis to ensure stable coexistence and as a mechanism to ward off mycoparasitic fungi and bacteria. These mutual benefits are extended into a tripartite context via the provision of enhanced protection to the host plant through the induction of systemic resistance.

Assessing the potential role of arbuscular mycorrhizal fungi in improving the phytochemical content and antioxidant properties in Gomphrena globosa

Strategies to increase the secondary metabolite production, obtained from medicinal plants has been the topic of research in recent years. The symbiotic interaction between arbuscular mycorrhizal fungi and plants allows host-fungus pairings to enhance secondary metabolite synthesis. Therefore, the current study investigated the effect of inoculating two distinct AMF species discretely as well as in conjunction on the flower-derived secondary metabolites in Gomphrena globosa. The findings showed that the plants inoculated with combined treatment exhibited higher total phenolic (50.11 mg GAE/g DW), flavonoids (29.67 mg QE/g DW), saponins (122.55 mg DE/g DW), tannins (165.71 TAE/g DW) and terpenoid (8.24 mg LE/g DW) content in the methanolic extract. HPTLC examination showed the existence of kaempferol and benzoic acid with the highest amount (0.90% and 5.83% respectively) observed in the same treatment. FTIR analysis revealed functional group peaks with increased peak intensity in the combination treatment. Higher antioxidant activities such as DPPH (IC50: 401.39 µg/mL), ABTS (IC50: 71.18 µg/mL) and FRAP (8774.73 µM Fe (II) equivalent) were observed in the methanolic extract of combined treatment. To our knowledge, this is the first study on the impact of AMF inoculation on bioactive compounds and antioxidant activities in G. globosa flowers. Moreover, this study could lead to the development of novel pharmaceuticals and herbal remedies for various diseases.

Interactive effects of arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) on the alleviation of salt stress in wheat

Interactive effects of arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) on the alleviation of salt stress in wheat

Unraveling the impact of global change on glomalin and implications for soil carbon storage in terrestrial ecosystems

Glomalin-related soil protein (GRSP) is a potential byproduct of arbuscular mycorrhizal fungi (AMF) and a major contributor to the passive soil organic carbon (SOC) pool. Despite its crucial role in SOC storage, we know little about the response of GRSP to anthropogenic global change factors (GCFs). Here, using 530 observations from 107 primary studies, we conducted a global meta-analysis to unravel the effects of multiple GCFs (climate change, plant invasion (PI), wildfire, urbanization, land-use change (LUC), and nutrient addition (nitrogen; N, phosphorus; P, and potassium; K) on two functional GRSP fractions (easily extractable- (EE-) and total- (T-) GRSPs) in terrestrial ecosystems. We found that elevated carbon-dioxide increased T-GRSP by 28%, combined NP addition by 39.9%, and NPK addition by 29.5%. Climate warming and alone N addition increased EE-GRSP solely by 2.4% and 13.6%, respectively, but did not influence T-GRSP. However, urbanization and drought decreased T-GRSP by 26% and 15%, respectively. The LUC from natural ecosystems to cropland decreased T-GRSP by 40%, while afforestation in croplands increased it by 32%. Other GCFs (PI, wildfire, and P) had non-significant effects on GRSP probably because of (i) minor changes in AMF activity and (ii) the counterbalancing of effects by opposite processes. GCF impacts were robust when applied at higher intensities for medium-to-long durations (3–10＋ years) in humid conditions and clay-rich soils. The sandy soils experienced greater T-GRSP losses during LUC. Increases in T-GRSP were positively correlated with AMF-root colonization, soil mean-weight diameter, and SOC content. Further, our structure equation model confirmed that GCFs directly influence SOC by altering AMF-GRSP production and indirectly affecting soil aggregate formation and protection, suggesting that optimizing GRSP production can enhance SOC sequestration.

Rhizophagus intraradices mediated mitigation of arsenic toxicity in wheat involves differential distribution of arsenic in subcellular fractions and modulated expression of Phts and ABCCs

Biomagnification of arsenic in food chain through wheat consumption poses a serious threat to human health. Therefore, it is necessary to elucidate mechanism of arsenic tolerance and detoxification in wheat. The study aimed to unravel the strategies adopted by arbuscular mycorrhizal fungi to alleviate arsenic toxicity in wheat. To accomplish this, independent and interactive effects of arsenic and Rhizophagus intraradices were assessed. Colonization by R. intraradices resulted in lower expression of high-affinity phosphate transporters (Phts) in comparison with non-mycorrhizal (NM) plants, thereby lowering arsenic concentrations in mycorrhizal (M) plants. Additionally, the subcellular fractionation analysis indicated differential distribution of arsenic. In NM plants, arsenic accumulated primarily in cell wall and organelle fractions. Conversely, in M plants arsenic was more concentrated in the cell wall and vacuolar fractions. This was related to higher levels of hydroxyl and aldehyde groups in cell wall fraction of root along with increased expression of C-type ATP-binding cassette transporters in root and leaves. These factors enabled effective sequestration of arsenic in the cell wall and vacuoles of M plants, thereby reducing its toxicity. Furthermore, the proportion of inorganic arsenic was lower in M plant, as it transformed it into less toxic organic forms.

Straw management and fertilization improve soil aggregate stability by inducing biological binding agents and specific keystone genera

Improving soil aggregate stability through proper fertilization management is essential for crop growth. However, how different fertilization regimes affect soil aggregate stability driven by microorganisms and biological binding agents remains largely unexplored. For this purpose, we conducted a 9-year field experiment involving two soil textures (i.e., loam and clay soils) and five fertilization regimes (i.e., no fertilizer or crop straw return (CK), crop straw return (S), chemical fertilization (N), crop straw return with chemical fertilizer (SN), and crop straw return with chemical fertilizer and 20% nitrogen substituted with chicken manure (SNM)). Mean weight diameter (MWD) of soil aggregates, glomalin-related soil protein (GRSP) content, and microbial community composition were investigated. The SN and SNM treatments had similar MWD, which was 70.08–76.45% higher than the CK, and the S and N treatments had similar MWD, which was 20.35–34.76% higher than the CK, indicating better effects of SN and SNM on the improvement of the soil aggregate stability than the S or N treatment. High easily extractable GRSP and total GRSP contents contributed to the improved MWD. Meanwhile, some specific keystone genera identified from the keystone modules (co-occurring groups of soil biota including arbuscular mycorrhizal fungi, bacteria, and nonmycorrhizal fungi) were recognized as the important factors regulating the MWD, though the selected specific genera in the loam soil differed from the clay soil. Altogether, our results highlighted the fundamental role of the GRSP and selected specific keystone microbial taxa in improving the soil aggregate stability and provided a list of microbial taxa linking to MWD in different soils, which could be specifically targeted in specific soil.

The role of arbuscular mycorrhizal fungi in exotic plant invasion

The invasion success of exotic plants is largely determined by their invasiveness, which is influenced by soil abiotic properties and soil biota. Among these, arbuscular mycorrhiza fungi (AMF) can symbiosis with more than 80% of terrestrial plants and may be crucial to the successful invasion of exotic plants. Although many studies indicated that AMF can enhance the growth and competitiveness of invasive plants, some studies have also reported that AMF does not actually increase the invasiveness of invasive plants, and even inhibits it. This inconsistency is frequently attributed to the interactions between AMF and soil abiotic properties, especially soil nutrients like nitrogen and phosphorus, which significantly affect the symbiotic relationship between AMF and host plants. Here, we summarize the common hypothesis on invasion mechanisms, the relationship between AMF and host plants, the AMF's role in plant invasion, the control of invasiveness by soil abiotic properties, the interaction between AMF and soil abiotic properties, which benefits our understanding for the prevention and control of exotic invasive plants and the remediation of the soil at the invaded site.

Arbuscular mycorrhizal fungi affected soft wheat quality properties and nutritional index by regulating the composition and secondary structure of protein

Arbuscular mycorrhizal fungi (AMF) inoculation has important regulatory influence on plant growth and nitrogen uptake, which are intimately associated with soft wheat yield and quality. The study aimed to investigate the impact of AMF inoculation on soft wheat grain yield, protein compositions, protein quality, secondary structure of gluten, dough properties and biscuits baking quality. In this study, AMF inoculation significantly increased grain yield. AMF inoculation decreased grain protein content by 5.1%, glutenin content by 8.5%, GMP by 14.3%, and HMW-GS by 8.8% compared with CK. Conversely, AMF inoculation increased the ratio of gliadin/glutenin. Further analysis showed AMF treatment had a looser gluten network than CK, significantly reduced β-sheet and β-turn content, while α-helix content increased. The nutritional index of grain protein was slightly reduced under AMF inoculation, yet the biological value was improved. Reduced wet gluten content, gluten performance index and dough development time under AMF treatment through regulation of soft wheat protein composition and gluten protein structure. Therefore, biscuits in AMF treatment showed reduced thickness, hardness, significantly greater spread ratio and sensory score compared with CK. These indicate that AMF application would be a beneficial agronomic practice to synergistically optimize yield and grain quality in soft wheat.

Integrative approaches to improve litchi (Litchi chinensis Sonn.) plant health using bio-transformations and entomopathogenic fungi

Bio-transformations refer to the chemical modifications made by an organism on a chemical compound that often involves the interaction of plants with microbes to alter the chemical composition of soil or plant. Integrating bio-transformations and entomopathogenic fungi into litchi cultivation can enhance symbiotic relationships, microbial enzymatic activity in rhizosphere, disease suppression and promote overall plant health. The integration of biological formulations and entomopathogenic fungi can significantly influence growth, nutrient dynamics, physiology, and rhizosphere microbiome of air-layered litchi (Litchi chinensis Sonn.) saplings. Biological modifications included, K-mobilizers, AM fungi, Pseudomonas florescence and Azotobacter chroococcum along with Metarhizium, entomopathogenic fungi have been used. The treatments included, T1-Litchi orchard soil + sand (1:1); T2-Sand + AM fungi + Azotobacter chroococcum (1:2:1); T3-Sand + Pseudomonas florecence + K-mobilizer (1:1:1); T4- AM fungi + K-mobilizers (1:1); T5, P. Florecence + A. chroococcum + K-mobilizer (1:1:1); T6-Sand + P. florecence (1:2) and T7-Uninoculated control for field performance. Treatments T4-T6 were further uniformly amended with drenching of Metarrhizium in rhizosphere. T2 application significantly increased resident microbe survival, total chlorophyll content and root soil ratio in seedlings. A. chroococcum, Pseudomonas, K-mobilizers and AM fungi increased in microbial biomass of 2.59, 3.39, 2.42 and 2.77 times, respectively. Acidic phosphatases, dehydrogenases and alkaline phosphatases were increased in rhizosphere. Leaf nutrients reflected through DOP were considerably altered by T2 treatment. Based on Eigen value, PCA-induced changes at biological modifications showed maximum total variance. The study inferred that the bio-transformations through microbial inoculants and entomopathogenic fungi could be an encouraging strategy to enhance the growth of plants, health and productivity. Such practices align well with the goals of sustainable agriculture through biological means by reducing dependency on chemical inputs. By delving into these aspects, the research gaps including microbial processes, competitive and symbiotic relationships, resistance in microbes and how complex interactions among bio-transformations, entomopathogenic fungi and microbes can significantly impact the health and productivity of litchi. Understanding and harnessing these interactions can lead to more effective and sustainable farming practices.

Micorrizas arbusculares y endófitos septados en tres especies de Thelypteridaceae de ambientes riparios de las Yungas (Tucumán, Argentina)

Background and aims: The status of the presence of arbuscular mycorrhizal fungi (AMF) in lycophytes and ferns has been analysed in 11% of them. This work aims to characterise and quantify the AMF colonisation and to characterise septate endophytes present on the roots of the Thelypteridaceae: Amauropelta jujuyensis, A. nubicola, and Pelazoneuron patens. M&M: Ten individuals per species were collected in August 2022. Conventional staining and techniques were used to estimate colonisation. Results: The root of Amauropelta jujuyensis, A. nubicola, and Pelazoneuron patens showed AMF with Arum and Paris morphological types simultaneously. The hyphal colonization showed no significant difference among species, arbuscular colonization was significantly higher in A. jujuyensis, while vesicular colonization was considerably higher in A. nubicola. In addition, septate endophytes were evident in the species of the genus Amauropelta. Conclusion: The association of AMF and other fungal endophytes with the native Argentine Thelypteridaceae Amauropelta jujuyensis, A. nubicola, and Pelazoneuron patens is evidenced for the first time in riparian environments of the Yungas. The coexistence of Arum and Paris morphological types in the three studied fern species is demonstrated.