Arbuscular Mycorrhizal Colonization Research Articles

Improved Waterlogging Tolerance in Roots of Cucumber Plants after Inoculation with Arbuscular Mycorrhizal Fungi

Mycorrhizal symbiosis enhances host plant resistance to various unfavorable environmental stresses, but whether and how it also enhances waterlogging tolerance in cucumber plants is not known. The objective of this study was to analyze the effect of Paraglomus occultum inoculation on biomass production, osmolyte levels, and the expression of 12 heat shock protein 70 (Hsp70) genes and 14 plasma membrane intrinsic protein (PIP) genes in the roots of cucumber plants under a short-term waterlogging stress (WS) (5 days) condition. Although the short-term WS treatment significantly inhibited the arbuscular mycorrhizal fungal colonization of roots, the inoculation with arbuscular mycorrhizal fungi (AMFs) significantly increased leaf, stem, and root biomass under WS. AMF inoculation also significantly increased root glucose, sucrose, betaine, and proline contents, along with decreased fructose levels, compared with the uninoculated control. More CsHsp70 and CsPIP genes were up-regulated in AMF-inoculated plants than in AMF-uninoculated plants in response to WS. AMF inoculation showed no significant effect on the expression of any of the examined CsHsp70 genes under no-waterlogging stress, but it did raise the expression of 11 of 12 CsHsp70 genes under WS. AMF colonization also down-regulated or had no effect on CsPIP expression under no-waterlogging stress, whereas it up-regulated the expression of 12 of the 14 CsPIP genes under WS. It is concluded that AMF inoculation enhances waterlogging tolerance in cucumber plants by increasing osmolyte levels and stress-responsive gene (CsPIP and CsHsp70) expression.

Arbuscular Mycorrhizal Fungi Improve Lycium barbarum Potassium Uptake by Activating the Expression of LbHAK.

Arbuscular mycorrhizal (AM) fungi can establish a mutualistic relationship with the roots of most terrestrial plants to increase plant nutrient uptake. The effects of potassium uptake and transport by AM symbiosis are much less reported compared to other nutrients. In this research, a heterologous yeast system was used to verify that the LbHAK has capacity for potassium uptake. The split-roots system implemented using seedlings of Lycium barbarum confirmed that R. irregularis locally induced LbHAK expression, which means that LbHAK is only expressed in mycorrhizal roots. Furthermore, the impacts of overexpression of LbHAK on the growth, nutrients and water uptake, and transport of mycorrhizal tobacco (inoculation with Rhizophagus irregularis) at 0.2 mM and 2 mM K conditions were assessed. The mycorrhizal tobacco growth and potassium accumulation were significantly enhanced through LbHAK overexpression in tobacco. In addition, overexpression of LbHAK substantially enhanced phosphorus content, while stimulating the expression of NtPT4, Rir-AQP1, and Rir-AQP2 in mycorrhizal tobacco. Moreover, LbHAK overexpression greatly promoted AM colonization. LbHAK has a potential role in facilitating potassium absorption through the mycorrhizal pathway, and overexpression of LbHAK in tobacco may promote the transport of potassium, phosphorus, and water from AM fungi to tobacco. These data imply the important roles played by the LbHAK in AM-fungi-induced potassium uptake in L. barbarum and in improving plant nutrients and AM colonization.

Tradeoffs among root functional traits for phosphorus acquisition in 13 soybean genotypes contrasting in mycorrhizal colonization.

Plants have adapted to acquire phosphorus (P) primarily through advantageous root morphologies, responsive physiological pathways, and associations with mycorrhizal fungi. Yet, to date, little information exists on how variation in arbuscular mycorrhizal (AM) colonization is coordinated with root morphological and physiological traits to enhance P acquisition. Thirteen root functional traits associated with P acquisition were characterized at full bloom stage in pot cultures under low soil P availability conditions for 13 soybean genotypes contrasting in AM colonization. Significant variation in root functional traits was observed in response to low P stress among the 13 tested soybean genotypes contrasting in AM colonization. Genotypes with low AM colonization exhibited greater root proliferation but with less advantageous root physiological characteristics for P acquisition. In contrast, genotypes with high AM colonization exhibited less root growth but higher phosphatase activities and carboxylate content in the rhizosheath. Root dry weights, and contents of carbon and P were positively correlated with root morphological traits of different root orders and whole root systems, and were negatively correlated with AM colonization of fine roots and whole root systems, as well as, rhizosheath phosphatase activities and carboxylate contents. These results taken in combination with significant positive correlation between plant P content and root morphological traits indicate that root morphological traits play a primary role in soybean P acquisition. The results suggest that efficient P acquisition involves tradeoffs among carbon allocation to root proliferation, mycorrhizal symbiosis, or P-mobilizing exudation. Complementarity and complexity in the selection of P acquisition strategies was notable among soybean genotypes contrasting in AM colonization, which is closely related to plant C budgeting.

Exploring the Influence of Arbuscular Mycorrhizal Symbology on the Antioxidant Potential of Liverwort Asterella multiflora: A Comprehensive Study on Rhizoid and Thallus Anatomy

Arbuscular mycorrhizal (AM) symbiosis is a vital ecological interaction between plants and fungi that enhances nutrient uptake and plant resilience. While extensively studied in vascular plants, AM symbiosis in liverworts remains relatively unexplored. Six populations of Asterella multiflora were collected throughout the year to scan for arbuscular mycorrhizal colonization and enzymatic antioxidant activity. Percent mycorrhizal colonization was measured in smooth as well as tuberculated rhizoids. Anatomical detail of the thallus was also observed. Arbuscules were observed in the cells of the storage zone of the thallus. Enzymatic antioxidant activities, i.e., superoxide dismutase (SOD), guaiacol peroxidase (GPOX), catalase (CAT), ascorbate peroxidase activity (APOX) and glutathione reductase activity (GR) were calculated. Maximum enzyme activity was observed in ascorbate peroxidase, which calculated 1.92-2.09 UA/mg protein, while catalase showed minimum activity of 0.01 UA/mg protein. A positive correlation was observed between enzyme activities and percent mycorrhizal colonization. This study delves into AM symbiosis in liverworts, focusing on Asterella multiflora and investigates the impact of AM colonization on enzymatic antioxidant activities, i.e., superoxide dismutase (SOD), guaiacol peroxidase (GPOX), catalase (CAT) ascorbate peroxidase activity (APOX) and glutathione reductase activity (GR). Antioxidants play a crucial role in stress tolerance and plant health, making them central to understanding the implications of symbiotic relationships.

Optimizing the manure substitution rate based on phosphorus fertilizer to enhance soil phosphorus turnover and root uptake in pepper (Capsicum).

In contemporary agriculture, the substitution of manure for chemical fertilizer based on phosphorus (P) input in vegetable production has led to a significant reduction in P fertilizer application rates, while, the effect of manure substitution rates on soil P transformation and uptake by root remain unclear. This research conducts a pot experiment with varying manure substitution rates (0%, 10%, 20%, 30%, 40%, 50%, 75% and 100%) based on P nutrient content to elucidate the mechanisms through which manure substitution affects P uptake in pepper. The result showed that shoot and root biomass of pepper gradually increased as manure substitution rate from 10% to 40%, and then gradually decreased with further increases in the substitution rate. Soil alkaline phosphatase activity and arbuscular mycorrhizal (AM) colonization gradually increased with manure substitution rates improvement. Specifically, when the substitution rate reached 30%-40%, the alkaline phosphatase activity increased by 24.5%-33.8% compared to the fertilizer treatment. In contrast, phytase activity and the relative expression of phosphate transporter protein genes in the root system was declined after peaking at 30% manure substitution. Additionally, soil available P remained moderate under 30%-40% substitution rate, which was reduced by 8.6%-10.2% compared to that in chemical fertilizer treatment, while microbial biomass P was comparable. In the current study, soil labile P similar to or even higher than that in chemical fertilizer treatment when the substitution rate was ≤40%. Correlation heatmaps demonstrated a significant and positive relationship between soil available P and factors related to labile P and moderately labile P. This finding suggested that substituting 30%-40% of chemical P with manure can effectively enhance root length, AM colonization, soil enzyme activity, soil labile P, and consequently improve P uptake in pepper. These findings provide valuable insights for future organic agricultural practices that prioritize P supply, aiming to standardize organic P management in farmland and achieve high crop yields and maintain soil health.

Rapid positive response of young trees growth to warming reverses nitrogen loss from subtropical soil

Abstract Global warming is widely expected to alter nitrogen (N) cycling in terrestrial ecosystems by accelerating N transformations in soils. However, it is unclear how warming will affect plant–soil N cycling in subtropical ecosystems. Here, we measured the N transformations including net ammoniation, nitrification, nitrous oxide emissions and nitrate in soil solution throughout the plant–soil continuum with 2 years of experimental soil warming (+5°C) in a young subtropical Chinese fir mesocosm. Seasonal variations of soil and plant (foliage and root) N concentrations and isotopes (δ15N), foliar water use efficiency and arbuscular mycorrhizal colonization rate were measured. Soil warming significantly increased net ammonization and nitrification of the soil, together with the transient positive response observed in inorganic N of the soil. Warming increased nitrate N fluxes in soil solution and nitrous oxide emissions in the first year but not in the second year, suggesting N losses through leaching and gaseous in the initial period of warming. Warming primarily induced enrichment of 15N in foliage relative to the soil, which was attributed to the trade‐offs of persistent increases in plant N uptake caused by enhanced tree growth and a decrease in N losses with continuous warming. Furthermore, young trees' growth and N uptake capacity can rapidly acclimate to climate warming as a result of warming‐induced increases in arbuscular mycorrhizal colonization and foliar water use efficiency. Our findings highlight that warming accelerates the plant–soil N cycle and promotes young trees' growth and N uptake, which in turn reduces soil N lost from this subtropical ecosystem. Therefore, our study suggests that the competition for N between plants and microbes governs whether subtropical forests are opened or closed N cycle systems under climate warming. We predict that subtropical young forests can still maintain their high productivity because young trees can maintain their N uptake capacity and adequate soil N supply in facing future climate warming. Read the free Plain Language Summary for this article on the Journal blog.

Responses of Root Exudates of Alfalfa to Arbuscular Mycorrhizal Fungi Colonization, High Temperature, and Cadmium Exposure

Responses of Root Exudates of Alfalfa to Arbuscular Mycorrhizal Fungi Colonization, High Temperature, and Cadmium Exposure

Effect of Cinnamon Leaf Compost on Selected Soil Properties in Cinnamon (Cinnamomum zeylanicum Blume) Growing Soils

Integrated nutrient-management programs incorporating organic and inorganic fertilizers have been suggested to increase crop yields and reduce adverse environmental impacts in intensive agriculture. This study was conducted to investigate the effect of long-term cinnamon leaf compost (CLC) application on some selected physical, biological and chemical soil properties and the horizontal and vertical distribution of some selected soil properties in cinnamon-growing soils. The study was conducted in the National Cinnamon Research and Training Center, Palolpitiya, from January to April 2022. The experimental design was Randomized Complete Block Design (RCBD) with six treatments (T1-Control, T2-Current recommendation (CR), T3-3/4 CR with 5 t/ha/yr CLC, T4-1/2 CR with 10 t/ha/yr CLC, T5-1/4 CR with 15 t/ha/yr CLC, T6-20 t/ha/yr CLC) and three replicates. Soil samples were collected considering three horizontal distances (15, 30 and 45 cm) and with three depths (10, 20 and 30 cm). Soil physical properties (aggregate stability, bulk density, soil moisture), chemical properties (soil organic carbon (SOC), pH, electrical conductivity (EC)), and biological properties (arbuscular mycorrhizal root colonization) were determined. Water stable aggregate (WSA), SOC, and soil pH were significantly affected by the treatments, and all the variables except EC were significantly affected by the soil depth (p<0.05). Soil pH was the only variable that was significantly affected by the horizontal distance (p<0.05). Only SOC and pH have shown a significant interaction effect among treatments and depth. The application of CLC (20 t/ha/yr) significantly increases the WSA and SOC. Arbuscular mycorrhizal fungi root colonization was increased with the incorporation of CLC. Continuous application of inorganic fertilizers (T2) caused soil compaction and acidification. WSA, soil pH, and SOC were significantly improved within the 0-10 cm soil depth. The best performances of WSA, pH, and EC were shown in 30-45 cm and SOC in 15–30 cm horizontal distance from the plant base and 0-10 cm soil depth with the application of 1/2 CR and 10 t/ha/yr CLC comparison to other fertilizer combinations. 
 Keywords: Aggregates, Mycorrhizae, pH, Soil organic carbon

Foliar herbivory‐enhanced mycorrhization is associated with increased levels of lipids in root and root exudates

Abstract Insect herbivory can affect interactions between plants and arbuscular mycorrhizal (AM) fungi through herbivore‐modified root carbon pools, while the specific metabolic changes underlying fungal responses to herbivory are poorly understood. Here we explored the impacts of foliar herbivory and mechanical wounding on AM colonisation and AM community composition of common ragweed (Ambrosia artemisiifolia) and the role of root metabolites in mediating these effects. Foliar insect herbivory enhanced AM colonisation, whereas mechanical wounding only enhanced AM colonisation in combination with application of caterpillar oral secretions. Meanwhile, the relative abundance of Glomus species was increased in root endosphere, rhizoplane and rhizosphere soils after foliar herbivory. Foliar herbivory also increased the concentrations of fatty acids in roots but decreased phenolics, and their concentrations were significantly correlated with AM colonisation. Addition of exudates from plants exposed to herbivory resulted in increases in AM colonisation of plants without herbivory. Moreover, widely targeted metabolomic analyses revealed that foliar herbivory enhanced the relative abundance of lipids and decreased phenols in root exudates. Synthesis. We show that plants can enhance their associations with arbuscular mycorrhizal (AM) fungi when subject to above‐ground herbivory, possibly mediated by herbivore‐induced increases in the levels of root lipids. Our findings highlight the role of root lipids in above‐below‐ground biological interactions, providing novel insights into plant‐AM fungi integrative responses to biotic stresses.

Boosting species evenness, productivity and weed control in a mixed meadow by promoting arbuscular mycorrhizas.

Lowland meadows represent aboveground and belowground biodiversity reservoirs in intensive agricultural areas, improving water retention and filtration, ensuring forage production, contrasting erosion and contributing to soil fertility and carbon sequestration. Besides such major ecosystem services, the presence of functionally different plant species improves forage quality, nutritional value and productivity, also limiting the establishment of weeds and alien species. Here, we tested the effectiveness of a commercial seed mixture in restoring a lowland mixed meadow in the presence or absence of inoculation with arbuscular mycorrhizal (AM) fungi and biostimulation of symbiosis development with the addition of short chain chito-oligosaccharides (CO). Plant community composition, phenology and productivity were regularly monitored alongside AM colonization in control, inoculated and CO-treated inoculated plots. Our analyses revealed that the CO treatment accelerated symbiosis development significantly increasing root colonization by AM fungi. Moreover, the combination of AM fungal inoculation and CO treatment improved plant species evenness and productivity with more balanced composition in forage species. Altogether, our study presented a successful and scalable strategy for the reintroduction of mixed meadows as valuable sources of forage biomass; demonstrated the positive impact of CO treatment on AM development in an agronomic context, extending previous observations developed under controlled laboratory conditions and leading the way to the application in sustainable agricultural practices.

Effect of organic pest control products on Arbuscular Mycorrhizal colonization in Bulgarian rose plantations: A two-year field study

This two-year field study aims to investigate the impact of organic pesticides used in organic Damask rose (Rosa damascena Mill.) fields on Arbuscular Mycorrhizal Fungal (AMF) colonization. Conducted in the renowned Rose Valley of Bulgaria, specifically in the village of Kliment, the experiment employed a randomized complete block design with two rows of 21 plants each in organic certified plots. The results revealed low AMF colonization in the first year, ranging between 14.78% and 20.89%, with no significant differences between treatments. In the second year, while no significant differences were observed between treatments (ranging from 48.00% to 76.49%), there was a notable increase in AMF colonization compared to the initial sampling. The study concluded that specific organic pesticides, including Neemazal, Limocide, Phytosev, and Nano sulfur, had minimal negative effects on AMF colonization. These findings contribute to understanding the implications of organic farming practices on AMF and soil health in the context of Damask rose cultivation.

Toxic effect of mercury on arbuscular mycorrhizal fungi colonisation and physiological status of three seed-based Miscanthus hybrids

BackgroundCurrently, mercury pollution is a widespread problem in the world. As mercury is difficult to remove from the environment, it has long-term negative effects on soil health and human life. One of the techniques to stabilise Hg is phytostabilisation, which can be supported by arbuscular mycorrhizal fungi (AMF). MethodsIn a 4-month pot experiment, we investigated the suitability of three seed-based Miscanthus hybrids (GNT3, GNT34, GNT43) for growth on soils heavily polluted with mercury (6795.7 mg kg-1). During the experiment, the effects of high soil contamination with mercury on physiological parameters and colonisation of roots of seed-based Miscanthus hybrids by indigenous AMF from Hg-contaminated and uncontaminated soils were investigated. ResultsA high pseudo-total Hg concentration (6795.75 mg kg-1) in soil was found. The Hg content in the aerial part of GNT34 grown on Hg-contaminated soil was 1.5 times and 3 times higher than GNT3 and GNT43, respectively. The Hg content in the roots of GNT3 on Hg-contaminated soil was 25% and 10% lower than that of GNT34 and GNT43, respectively. The N content in the aboveground part of GNT34 in the Hg variant was 13.5% lower compared to the control soil. The P and K content in the shoots of the Miscanthus hybrids was lower in the plants grown on Hg-contaminated soil. The P content in GNT43 in the Hg variant was 33% and 19% lower than in GNT34 and GNT3, respectively. The K content in GNT34 in the Hg variant was 24.7% and 31.4% higher than in GNT43 and GNT3, respectively. The dry weight of the shoots and roots as well as the shoot height of the Miscanthus hybrids were lower in Hg-contaminated soil. Lower values of AMF root colonisation parameters (F, M) were observed in the plants in the Hg variant. In the Hg variant, a lower photosynthetic rate and a decrease in chlorophyll content were observed in the leaves of the Miscanthus hybrids. In the Hg variant, an increase in the content of flavonols was observed. The strongest toxic effect of mercury on the light phase of photosynthesis was measured in GNT34. ConclusionSoils heavily contaminated with mercury negatively affected the physiological parameters of Miscanthus, as evidenced by a decrease in photosynthetic rate and biomass. The ability of indigenous AMF from Hg-contaminated soils to colonise the roots of seed-based Miscanthus hybrids was limited.

Poultry litter biochar soil amendment affects microbial community structures, promotes phosphorus cycling and growth of barley (Hordeumvulgare)

Phosphorus (P) is a non-replaceable, finite component of fertilizers. The imbalanced resource distribution and possible depletion of P impose challenges on current crop production worldwide. The aim of this study was to assess the impact of poultry litter biochar on plant growth and P mobilizing capability of the microbiome in comparison to a mineral fertilizer application. Spring barley (Hordeum vulgare) was grown in microcosms using a P-limited soil, fertilized with 0 (control), 50 (fertilizer) kg P ha−1 or a poultry litter biochar amendment (biochar, 2% w/w). Biochar amended rhizospheres had significantly higher phosphonate-utilizing bacteria, phoC and phoD gene (acid and alkaline phosphatase) copy numbers and improved P availability. Spring barley dry matter yields were significantly higher for biochar and fertilizer over control; however, P uptake with biochar was higher than with fertilizer. Furthermore, biochar had higher arbuscular mycorrhizal colonization and significantly raised soil pH. Fingerprint-analysis showed significant differences between all treatments for bacterial and fungal communities. 16S rRNA gene-based sequencing analysis revealed increased relative abundance of the phyla Actinobacteriota and Chloroflexi in biochar compared to control, potentially contributing to the ameliorated plant growth conditions. Pearson correlations of both phyla was positive with a range of P cycling variables as well as Morgan's P but negative with acid phosphatase activity. FAPROTAX analysis revealed positive correlations of aromatic compound degradation with phoC and phoD gene abundance, highlighting a possible link between biodegradation and P release. In conclusion, poultry litter biochar could potentially replace mineral P fertilizer for sustainable plant growth in P depleted soil environments.

Soil Physico-Chemical Properties and Different Altitudes Affect Arbuscular Mycorrhizal Fungi Abundance and Colonization in Cacao Plantations of Cameroon

Soil Physico-Chemical Properties and Different Altitudes Affect Arbuscular Mycorrhizal Fungi Abundance and Colonization in Cacao Plantations of Cameroon

Wall-associated kinase GhWAK13 mediates arbuscular mycorrhizal symbiosis and Verticillium wilt resistance in cotton.

The cell wall is the major interface for arbuscular mycorrhizal (AM) symbiosis. However, the roles of cell wall proteins and cell wall synthesis in AM symbiosis remain unclear. We reported that a novel wall-associated kinase 13 (GhWAK13) positively regulates AM symbiosis and negatively regulates Verticillium wilt resistance in cotton. GhWAK13 transcription was induced by AM symbiosis and Verticillium dahliae (VD) infection. GhWAK13 is located in the plasma membrane and expressed in the arbuscule-containing cortical cells of mycorrhizal cotton roots. GhWAK13 silencing inhibited AM colonization and repressed gene expression of the mycorrhizal pathway. Moreover, GhWAK13 silencing improved Verticillium wilt resistance and triggered the expression of immunity genes. Therefore, GhWAK13 is considered an immune suppressor required for AM symbiosis and disease resistance. GhWAK7A, a positive regulator of Verticillium wilt resistance, was upregulated in GhWAK13-silenced cotton plants. Silencing GhWAK7A improved AM symbiosis. Oligogalacturonides application also suppressed AM symbiosis. Finally, GhWAK13 negatively affected the cellulose content by regulating the transcription of cellulose synthase genes. The results of this study suggest that immunity suppresses AM symbiosis in cotton. GhWAK13 affects AM symbiosis by suppressing immune responses.

Arbuscular mycorrhizal colonization of Scleria sumatrensis as a member of Cyperaceae family commonly known as non-mycorrhizal host plant

Cyperaceae is not strictly a non-mycorrhizal host plant family, and the mycorrhizal status of its member could be influenced by environmental conditions. Scleria sumatrensis, a member of Cyperaceae grown natively as a pioneer plant in a disturbed area, could be used as a source of native arbuscular mycorrhizal fungal (AMF) inoculum. Thus, this study aimed to analyze the mycorrhizal status of the S. sumatrensis grown natively in Martabe, North Sumatra, Indonesia, for revegetation purposes. The analysis was carried out by measuring root colonization characteristics and spore diversity in the rhizosphere soils of the S. sumatrensis. The roots were stained and measured for AM colonization characteristics. While the AMF spores were obtained using the wet sieving and decanting method and were identified based on morphological characteristics. The results indicated that the roots of S. sumatrensis were colonized by AMF in good-quality formed entry points, internal hyphae, arbuscules, and vesicles. The AMF associated with S. sumatrensis identified were relatively diverse; consisted of Acaulospora sp., Acaulospora cf. mellea, Glomus sp. 1, Glomus sp. 2, Glomus sp. 3, and Glomus sp. 4. This is the first report showing that S. sumatrensis is a mycotrophic plant in the family of Cyperaceae.

Arbuscular Mycorrhizal Fungi Colonization of Jatropha curcas Roots and Its Impact on Growth and Survival under Greenhouse-Induced Hydric Stress

Arbuscular mycorrhizal fungi (AMF) provide benefits to host plants by enhancing nutrition and overall fitness. In this study, AMF species were isolated from the soil rhizosphere of Jatropha curcas and were identified and evaluated for their potential in fostering the development of Jatropha seedlings within a controlled greenhouse environment. The first experiment assessed the interplay between hydric stress and AMF inoculation on mycorrhizal colonization. The next experiment examined the impact of quercetin on mycorrhizal colonization. Out of 204 glomerospores corresponding to 28 species spanning 10 genera, Acaulospora (14) and Scutellospora (5) were the most abundant taxa. Six new records of AMF for Costa Rica are reported. Mycorrhizal colonization was observed in 43.2% of Jatropha plants (34.7% by AMF typical hyphae; arbuscules 8.9%; coils 5.6%; and vesicles 5.4%). Significant survival effects due to AMF inoculation under hydric stress were observed. On day 85, non-mycorrhizal plants subjected to hydric stress showed a mere 30% survival rate, whereas their mycorrhizal counterparts under hydric stress exhibited survival rates of 80% and 100% with and without irrigation, respectively. Furthermore, plants with irrigation and mycorrhizas showed greater hydric stress tolerance and superior growth. The inoculated plants, irrespective of irrigation, demonstrated mycorrhizal colonization rates of 63% and 72%, respectively. Quercetin did not affect Jatropha’s growth, but there were differences in AMF root colonization. In summary, these findings accentuate the viability of a native consortium in augmenting Jatropha survival, warranting consideration as a potent biofertilizer within greenhouse settings. The AMF described can be used for Jatropha propagation programs.

Making partners in the city: impact of urban soil P enrichment on the partnership between an invasive herb and arbuscular mycorrhizal fungi in a tropical city.

The mutualistic relationship between plants and arbuscular mycorrhizal (AM) fungi is essential for optimal plant nutrition, enabling plants to better withstand biotic and abiotic stressors and enhancing survival, reproduction, and colonization of new environments. Activities, such as soil enrichment or compaction, may decrease the benefits of AM fungi for plants, potentially reducing interactions in urban environments. Here, we examine this prediction by studying how urbanization alters AM interactions with the invasive herb Ruellia nudiflora (Acanthaceae). We collected soil and plants from deep urban sites (DUS; e.g., sidewalks), open urban sites (OUS; parks), and rural sites (RS) to analyse soil nutrient content, plant morphology, AM colonization rates, spore density, richness, and diversity. Contrary to predicted, DUS had the lowest soil nutrient concentration, except for phosphorus, reducing AM colonization. This supports the prediction of reduced AM interactions in urban environments. We also found that potassium affects the AM association. Urban plants had smaller and more compact root systems compared to their rural counterparts, but there were no discernible differences in AM fungi communities between urban and rural environments. Phosphorus enrichment in sidewalks is the main driver of reductionof R. nudiflora-AM fungi interactions in Mérida. More studies are needed to gain a better understanding of how AM fungi contribute to plant colonization in urban environments.

Management of the mycorrhizal and rhizobial associations to mitigate the negative effects of Grevillea banksii on the development of Dalbergia trichocarpa an endemic tree species

This study aims to improve the development of Dalbergia trichocarpa, a Malagasy native tree species, on a soil invaded by Grevillea banksii, an invasive plant species in eastern part of Madagascar, by inoculating seedlings with mycorrhizal fungal, Rhizophagus irregularis and AMFn strains or rhizobial STM609 and Rn strains, or a mixed rhizobial-mycorrhizal strains. After five months of growth, the results showed that single or dual inoculation boosted significantly the development of D. trichocarpa, compared to control treatments and all parameters measured were markedly different between the time periods of plant invasions. Indeed, the dry mass of aerial biomass was significantly higher in inoculated seedlings than in control seedlings. It was also observed that the number of nodules and the arbuscular mycorrhizal colonization rates of D. trichocarpa increased significantly with inoculated plantlets. However, soil inoculated with the rhizobial strain STM609 alone showed a significantly high global soil microbial activity and the dual inoculation has promoted the soil acid phosphatase activity. These results suggest that dual inoculation with rhizobial and arbuscular mycorrhizal strains was significantly beneficial to the growth, nodulation and mycorrhizal colonization rates of D. trichocarpa in the soil overgrown by G. banksii, an invasive exotic plant species. Thus, this biotechnology can be used for restoration of degraded ecosystems in Madagascar with native tree species.

Fern species and seasonal variation alter arbuscular mycorrhizal fungal colonization and co-occurrence patterns in the Heishiding Natural Reserve, South China

The establishment of arbuscular mycorrhizal fungi (AMF) symbiosis is generally considered an important pathway that assists ferns in their adaption to a variable environment in the forest ecosystem. However, how both fern species and seasonal variation affect the symbiotic characteristics and AMF community structure remains largely unknown. In this study, the AMF colonization status of 19 fern species in the Heishiding Nature Reserve located in south China was assessed. The effects of seasons on AMF colonization and community structure were also determined. The results showed that both seasons and species significantly affected AMF colonization rate (1.88–56.03 %) and spore density (94–546/25 g dry soil). In addition, according to principal component analysis, in spring, AMF colonization and spore density differed considerably from other seasons. The total AMF sequences detected in spring were significantly higher than in winter (p < 0.05). Glomus was the dominant genus, accounting for >75 % of all sequences. The AMF Chao1 and Faith PD indexes of Blechnum orientale Linn as well as the Shannon and Simpson indexes of Selaginella doederleinii Hieron were significantly higher in spring than in winter (p < 0.05). According to partial least squares path modeling, season had a significant influence on AMF colonization by varying the AMF alpha diversity rather than their community composition. Notably, network analysis showed that seasonal variation induced differences in AMF network structure, keystone taxa, and the number of links between species. This study highlights the symbiotic relationship between ferns and AMF in different seasons. The results provide novel insights on terrestrial ecosystem management and fern conservation from the perspective of plant-AM symbiosis.