Effects Of Arbuscular Mycorrhizal Fungi Research Articles

Effects of rice husk biochar (RHB) with combined inoculation of arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) on growth of maize (Zea mays)

For optimal plant growth and productivity, agricultural activity is dependent on soil quality and nutrient availability. Soil amendment such as rice husk biochar (RHB), which abundantly found in Malaysia, are capable of improving soil fertility due to its longevity and other benefits to soil biota, including beneficial soil fungi and bacteria such as arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB). AMF are well-known for their capacity to improve plant nutrient uptake, particularly P, which is essential for plant growth. Similarly, PSB, which is a beneficial bacteria, are able to solubilize phosphate into soluble form thus enhance the P availability for plant. However, the combination effect of AMF and PSB in the presence of RHB is not known. Thus, in order to assess the effects of AMF and PSB in the presence of RHB on soil properties and maize growth, a pot experiment was done. Randomized completely block design (RCBD) arrangement was applied to the following treatments: T1 (control), T2 (RHB), T3 (AMF), T4 (PSB), T5 (+RHB, +AMF), T6 (+AMF, +PSB), T7 (+RHB, +PSB) and T8 (+RHB, +AMF, +PSB). About 10 t/ha RHB was added to the soils for treatments T2, T5, T7, and T8. Ten grams of AMF inoculum and double application of PSB were applied to their respective treatments. Plant growth and soils sampling were done at 45 days after planting (DAP). Results showed that T7 gave 137% root biomass and 123% P uptake higher than control. Our findings were in line with our hypothesis (application of RHB, AMF or PSB or their combination would improve maize growth compared to control, in which T8 gave highest root volume and 150% higher than control. The results suggested that there were positive and synergistic effects of beneficial soil microorganisms (AMF or/and PSB) either with or without RHB. Thus, these combined inoculations and RHB application could be used in biofertilizer formulations to increase the maize growth and yield in sustainable agriculture system.

Effect of AMF propagule dosage forms on the growth and production of Amaranthus tricolor L.

Red spinach (Amaranthus tricolor L) contains vitamins (A, B2, B6, K, and folate), proteins, carbohydrates, fats, minerals, fiber, iron, magnesium, manganese, potassium, and calcium. Red spinach also contain anthocyanins (red pigments) that function as antioxidants to prevent free radical oxidation. The use of biofertilizers can give benefits to the soil and plants. Mycorrhizal fungi can be used as a type of biological fertilizer. The application of arbuscular mycorrhizal fungi (AMF) in powder dosage forms can help the growth of plants. However, this dosage form has disadvantages, so a study is needed to determine the effectiveness of AMF in various dosage forms. This study applied the Latin Square Design (LSD), with three treatments of AMF propagule dosage forms, namely: tablets, sachets, and powders, without AMF application as a comparison/control. The results showed that the effectiveness of AMF propagule in dosage form sachets provided a reasonable infection rate with fertile plant growth and harvest index value was not significantly different from other dosage forms, due to the attack of plant-disturbing organisms before harvest. So, further research is needed to determine the effect of the AMF propagule dosage form in physiological review without invasion of plant-disturbing organisms.

Importance and roles of arbuscular mycorrhizal fungi in new Caledonian ultramafic soils

ABSTRACT Our knowledge about New Caledonian serpentine ecosystems has increased greatly during the past half-century, mainly thanks to Jaffré’s group. However, research on soil microflora and plant symbionts started only in the nineties and was mainly published during the last two decades. We aim to synthesize these studies, focusing particularly on arbuscular mycorrhizal fungi (AMF). Research on AMF consists firstly of a global and inventory approach aiming to produce a basic but essential lacking knowledge. These studies showed that AMF are abundant in ultramafic soils and concerned nearly all plant species of these ecosystems. Even Ni-hyperaccumulator plants and sedges, generally considered non-mycorrhizal, were found to be functionally colonized by AMF in New Caledonian ultramafic soils. The adaptation of AMF communities to the extreme conditions of these soils led to high levels of metal tolerance (particularly to Ni) and noticeable originality of the taxa. The influence of these symbionts on plant growth and adaptation was assessed in greenhouse and field conditions. An accurate selection of AMF isolates that improve plant growth, and plant metal tolerance was performed. It was demonstrated that combinations of AMF isolates with complementary functional traits showed highly synergistic effects on plant development. Finally, a partnership with a biotechnological company led to the production of an efficient commercial inoculant now used in the ecological restoration of mine-degraded areas. Today studies are focused mainly on the additive effects of AMF and mycorrhiza-helper bacteria.

Pengaruh Inokulasi Mikoriza Arbuskular dan Pupuk Kandang Sapi terhadap Pertumbuhan Semai Kayu Putih (Melaleuca Cajuputi) di Tanah Pasca Tambang Batu Kapur

Post-mining soil has low fertility so that the revegetation process will be hampered. The addition of soil ameliorants and proper plant selection are necessary for successful revegetation. The use of Arbuscular Mycorrhizal Fungi (AMF) and cow manure is expected to help plant growth on post-limestone mining soil. The aims of this study were (1) to analyze the interaction effect of AMF and cow manure on the growth of eucalyptus plants in post-lime mining soil, (2) to analyze the optimal dose of manure in increasing eucalyptus growth. This study used a completely randomized design (CRD) with two treatment factors (mycorrhizae and cow manure). The results showed that there was no effect of the interaction between AMF inoculation with cow manure. Giving AMF alone also did not significantly affect the growth of eucalyptus seedlings. While the single factor of cow manure had a significant effect on seedling growth, the best dose of cow manure was 15% which could increase growth in height and diameter by 28,04% and 38,41%, respectively, compared to control plants.
 Keywords: cow manure, eucalyptus, mycorrhiza, post-mining lime soil

Efektivitas Berbagai Produk Fungi Mikoriza Arbuskula Dalam Meningkatkan Produktivitas Stylosanthes guianensis Pada Tanah Masam

This study aimed to evaluate the effectiveness of Arbuscular Mycorrhizal Fungi (AMF) against Stylosanthes guianensis plants on acid soils. The research was conducted in the greenhouse of the Agrostology Laboratory of IPB. The research design used was a completely randomized design with 5 treatments and 8 replications, treatments were different types of AMF, without AMF (F0), commercial AMF (FU), AMF product IPB 1 (EM1), AMF product IPB 2 (EM2) and AMF product IPB 3 (EM3). AMF was given as much as 20 grams per planting hole. The given fertilizers were manure and NPK fertilizer. The treatment without AMF was given 100% of the recommended dose, while treatment with AMF was only given 50% of the dose. The results showed that there was no significant difference between treatments on growth variables (plant height, number of trifoliate leaves, number of branches, stem diameter and leaf chlorophyll). The type of AMF affected the fresh shoot production, and the highest was at EM1 (38.03 grams), as well as the number of root infections had a significant effect, and the highest production was at EM1 (77%). The conclusion in this study was that the use of AMF could reduce the use of manure and NPK 50% from the recommended dose, could increase the growth and productivity of Stylosanthes guianensis on acid soils and AMF product IPB 1(EM1) gave the best results.
 Key words: root infection, marginal soil, leguminous, Stylosanthes guianensis

Mycorrhizae influence plant vegetative and floral traits and intraspecific trait variation.

Arbuscular mycorrhizal fungi (AMF) can strongly influence host plant vegetative growth, but less is known about AMF effects on other plant traits, the relative impacts of AMF on vegetative growth versus floral traits, or AMF-induced intraspecific variation in traits. In an experimental greenhouse study, we inoculated seven species of wildflowers with six species of AMF in a factorial design. We assessed how the AMF-forb combinations influenced plant survival, vegetative biomass, and floral traits and whether AMF effects on floral traits were similar in magnitude and direction to effects on vegetative biomass. For one forb species, we investigated intraspecific plant trait variation within and across AMF treatments. AMF species varied from negative to positive in their effects on host plants. AMF often had inconsistent effects on vegetative biomass versus floral traits, and therefore, quantifying one or the other may provide a misleading representation of potential AMF effects. AMF treatments generated key variation in plant traits, especially floral traits, with potential consequences for plant-pollinator interactions. Given increased intraspecific trait variation in Linum lewisii plants across AMF species compared to uninoculated individuals or single AMF treatments, local AMF diversity and their host plant associations may scale up to influence community-wide patterns of trait variation and species interactions. These results have implications for predicting how aboveground communities are affected by belowground communities. Including AMF effects on not just host plant biomass but also functional traits and trait variation will deepen our understanding of community structure and function, including pollination.

The effects of arbuscular mycorrhizal fungi and deficit irrigation on the yield and sugar content of watermelons (Citrullus lanatus)

Many studies have demonstrated that arbuscular mycorrhizal fungi (AMF) and deficit irrigation (DI) have positive effects on the fruit yield or quality. This study aims to test whether the watermelon sugar content and yield can be improved by appropriate amounts of AMF and DI methods and to clarify the underlying physiological mechanism. Diploid and triploid watermelon cultivars and their pumpkin rootstock-grafted seedlings were treated with AMF, DI and DI + AMF in a randomised complete block design with five replications. The results showed that DI significantly reduced the relative water content (RWC), PN, alkaline α-galactosidase activity, but increased the insoluble acid invertase (IAI), sucrose synthase (SuSy) and sucrose phosphate synthase (SPS) activities compared with the well-watered (WW) treatment, which led to a decrease in the fruit yield and an increase in the fruit sugar content. Although the AMF improved the RWC, PN and alkaline α-galactosidase, IAI, SuSy and SPS activities in all the watermelon lines under both the DI and WW conditions, the improvement magnitude of these parameters was more pronounced in the pumpkin-root watermelon lines than the corresponding own-root watermelon lines, especially under the DI condition. The integrated application of AMF and DI increased the fruit yield to a level similar to the WW value in the pumpkin-root watermelon lines and sugar content to an optimal level in all the watermelon lines.

Allochthonous arbuscular mycorrhizal fungi promote Salix viminalis L.–mediated phytoremediation of polycyclic aromatic hydrocarbons characterized by increasing the release of organic acids and enzymes in soils

Polycyclic aromatic hydrocarbons (PAHs) are well known persistent organic pollutants that have carcinogenic, teratogenic, and mutagenic effects on humans and animals. Arbuscular mycorrhizal fungi (AMF) that can infest plant hosts and form symbioses may help plants to enhance potential rhizosphere effects, thus contributing to the rhizodegradation of PAH-contaminated soils. The present study aimed to assess the effectiveness of AMF on enhancing Salix viminalis–mediated phytoremediation of PAH-polluted soil and clarify the plant enzymatic and organic acid mechanisms induced by AMF. Natural attenuation (NA), phytoremediation (P, Salix viminalis), S. viminalis-AMF combined remediation using willow inoculated with Funneliformis mosseae (PM), Laroideoglomus etunicatum (PE), and Rhizophagus intraradices (PI) were used as strategies for the remediation of PAH-polluted soils. The results showed that AMF inoculation contributed to the dissipation of the high-molecular-weight PAH benzo (α) pyrene that had concentrations in PM, PE, and PI treatments of 40.1 %, 24.49 %, and 36.28 % of the level in the NA treatment, and 62.32 %, 38.05 %, and 56.38 % of the level in the P treatment after 90 days. The mycorrhizal treatment also improved the removal efficiency of phenanthrene and pyrene, as their concentrations were sharply decreased after 30 days compared to the NA and P treatments. The research further clarified the changes in rhizosphere substances induced by AMF. Organic acids including arachidonic acid, octadecanedioic acid, α-linolenic acid, 10,12,14-octadecarachidonic acid and 5-methoxysalicylic acid that can act as co-metabolic substrates for certain microbial species to metabolize PAHs were significantly increased in AMF-inoculated treatments. AMF inoculation also elevated the levels of polyphenol oxidase, laccase, and dehydrogenase, that played crucial roles in PAHs biodegradation. These findings provide an effective strategy for using AMF-assisted S. viminalis to remediate PAH-polluted soils, and the results have confirmed the key roles of organic acids and soil enzymes in plant-AMF combined remediation of PAHs.

Effect of arbuscular mycorrhizal inoculation on growth, mineral nutrient uptake, photosynthesis and antioxidant activities of black pepper cuttings

Arbuscular mycorrhizal (AM) fungi are one of most important soil microorganisms that can form mycorrhizal symbiosis with most of the terrestrial plants. In the present study, the effect of arbuscular mycorrhizal fungi inoculation on root colonization, growth, nutrition, photosynthetic gas exchange and antioxidant activities of black pepper cuttings were evaluated under polyhouse conditions. The single node cuttings of black pepper were grown in the presence and absence of AM combinations for 150 days under poly house. AM inoculated plants showed significantly higher mycorrhizal root colonization (95%) and spore numbers (312/50 g of sample). The effect of AM fungi was more prominent in improving root biomass than above ground biomass. Nutrient accumulations were higher in AM inoculated plants rather than uninoculated black pepper plants. Amount of acid phosphatase and dehydrogenase activity were significantly higher in AM inoculated soils. Net photosynthetic rate and stomatal conductance of AM colonized black pepper leaves were found to be significantly greater than uninoculated plants. The influence of AM was more prominent on poly phenol oxidase and β-glucanase activity in leaves than roots. In principal component analysis the scatter plot revealed variations of the effects of arbuscular mycorrhizal fungi on growth of black pepper cuttings. Based on these results, AM inoculation at the earlier stage of plant development could improve symbiosis, and increased plant growth in the nursery which may improve the performance after planting in the field.

Evaluation of the ef fect of native arbuscular mycorrhizal fungi an vermicompost leachate on the yield and quality of f ield-grown peanuts

The improvement of the symbiosis generated by arbuscular mycorrhizal fungi (AMF) against pathogenic microorganisms has been described, however, the ef fect of AMF in peanut crops is of interest due to the value of the productive chain that has not been fully attended. Therefore, this research work evaluated six treatments: (T1) Control plants without AMF, (T2) Plants with vermicompost leachate, (T3) Plants inoculated with commercial mycorrhizae, (T4) Plants inoculated with native mycorrhizae, (T5) Plants inoculated with commercial mycorrhizae + leachate and (T6) Plants inoculated with commercial mycorrhizae + native mycorrhizae; in this sense, mycorrhizal fungi were isolated, identifying Rhizoglomus clarum, Acaulospora alpina and Acaulospora af f. bireticulata, and inoculated in peanut plants in an area of 144 m2 in the open, so that, to corroborate the incidence of the treatments evaluated, agronomic variables such as height, width of biomass, foliar damage by Cercospora personata, number of f lowers, were evaluated during the pre-harvest every 15 days and the post-harvest variables were; leaf area index, root length, fruit and lipid yield, as well as the prof ile of fatty acids present in the fruit. Finally, peanut quality was evaluated according to CODEX STAN 200-1995, showing that the best treatment was leaching + commercial mycorrhizae, reporting yields of 65.05% of fruits and 58% of total lipids, mostly monounsaturated fatty acids (52 % oleic acid) followed by polyunsaturated (21% linoleic acid), f inally according to CODEX STAN 200-199 the peanuts obtained correspond to the basic quality with dimensions of 4 to 4.5 cm wide and long respectively, these peanuts cannot be exported but they can be marketed in the country for agro-industrial transformation, allowing improved agricultural practices by reducing the use of agrochemicals.

Efecto de los hongos formadores de micorriza arbuscular (HFMA) en la producción de aceites esenciales en romero (Rosmarinus officinalis L.) Effect of arbuscular mycorrhizal fungi (AMF) on essential oil production in rosemary (Rosmarinus officinalis L.).

An experimental greenhouse campaign was conducted to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on the production of essential oils in rosemary (Rosmarinus officinalis L.). For effect, a completely randomized experimental design was implemented, with three treatments composed of soil plus multisporic inoculum (Glomus spp, Acaulospora spp, Entrophosfora spp, Scutellospora spp.), soil plus monosporic inoculum (Entrophosfora colombiana), and the control treatment without inoculation, all of these with ten replicates per treatment. The soil used for all experimental units was sterilized and adjusted to 0.02 mg L-1 of P (phosphorus), the optimum concentration for the mycorrhizal condition. The response variables were: foliar P content, aerial dry mass, mycorrhizal colonization, and essential oil yield. The results of aerial dry mass indicate significant increases in the inoculated treatments compared to the control treatment. Leaf P showed no differences between treatments. The average mycorrhizal colonization of the inoculated treatments was 73%. As for the essential oils produced by the rosemary plants, the results were the inverse of those of the mass, where a higher yield was found in the control treatment. According to the data, the use of HFMA in the production of rosemary favors the development of the plant; on the other hand, the yield of essential oils could be compensated by the higher biomass produced, which would allow producers to increase the amount of oil extracted. Keywords: essential oils, arbuscular mycorrhizal fungi, Rosmarinus officinalis.

How arbuscular mycorrhizal fungi drives herbaceous plants' C: N: P stoichiometry? A meta-analysis

Plant element stoichiometry is fundamental for preserving growth-related terrestrial ecosystem structures and functions. However, effects of arbuscular mycorrhizal fungi (AMF) on herbaceous plant element stoichiometry (carbon (C), nitrogen (N), and phosphorus (P)) remain unclear. In this study, we aimed at evaluating the potential effects of AMF on herbaceous plant C, N and P concentration and their C:N:P stoichiometry worldwide through a quantitative meta-analysis. We observed that AMF reduced C:P and N:P ratios in the shoot of plants by 35.83 % and 54.23 %, respectively, and in plant root organs by 36.24 % and 46.35 %, respectively. Conversely, C:N ratios increased in roots by 6.61 %. The negative effect of AMF on N:P and C:P ratios in plant shoots and root organs is mainly attributed to the plant benefits in P and N concentrations. AMF impact on plant C:N:P stoichiometry depends on fungal and plant functional group identities and soil nutrient availability. Our results suggest that plant functional group identity affects plant nutrient concentration, which, in turn, controls herbaceous plant C:N:P stoichiometry. Overall, we emphasize the importance of abiotic and biotic environmental factors in changing AMF effects on plant element stoichiometry. Therefore, clarifying the relationship between AMF and herbaceous plant C:N:P stoichiometry will improve our understanding of herbaceous plant stoichiometric variations in terrestrial ecosystems.

Arbuscular mycorrhizal fungi enhance the drought resistance more significantly of the late‐successional psammophytes than that of the early ones

Improving drought tolerance of psammophytes is a challenge for vegetation restoration in arid lands. Despite extensive reports on the effect of arbuscular mycorrhizal fungi (AMF) on plant resistance, its enhancements of drought resistance for psammophytes from different successions stages have been rarely explored. Here, seedlings of the Artemisia wudanica (early succession), Hedysarum fruticosum (middle succession), and the Caragana korshinskii (late succession) were selected to investigate the effect of AMF on the growth of psammophytes in different successional stages. We found that the mycorrhizal colonization of late‐successional psammophytes with the AMF was greater than that of the early and mid‐successional psammophytes. The effect of AMF on drought resistance was stronger in late‐successional psammophytes and the promotion effect increased with the intensity of drought. The AMF reduced the difference between aboveground and belowground plant growth and promoted more belowground growth of psammophytes in the late‐successional stage. We concluded that AMF can enhance the drought resistance of psammophytes and has a more significant effect on the growth of plants from the late‐successional stage. This study highlighted the importance of AMF for psammophytes, providing a new approach to improving the growth of psammophytes under drought circumstances.

Physio-Biochemical and Transcriptomic Features of Arbuscular Mycorrhizal Fungi Relieving Cadmium Stress in Wheat.

Arbuscular mycorrhizal fungi (AMF) can improve plant cadmium (Cd) tolerance, but the tolerance mechanism in wheat is not fully understood. This study aimed to examine the physiological properties and transcriptome changes in wheat inoculated with or without Glomus mosseae (GM) under Cd stress (0, 5, and 10 mg·kg-1 CdCl2) to understand its role in wheat Cd tolerance. The results showed that the Cd content in shoots decreased while the Cd accumulation in roots increased under AMF symbiosis compared to the non-inoculation group and that AMF significantly promoted the growth of wheat seedlings and reduced Cd-induced oxidative damage. This alleviative effect of AMF on wheat under Cd stress was mainly attributed to the fact that AMF accelerated the ascorbate-glutathione (AsA-GSH) cycle, promoted the production of GSH and metallothionein (MTs), improved the degradation of methylglyoxal (MG), and induced GRSP (glomalin-related soil protein) secretion. Furthermore, a comparative analysis of the transcriptomes of the symbiotic group and the non-symbiotic group revealed multiple differentially expressed genes (DEGs) in the 'metal ion transport', 'glutathione metabolism', 'cysteine and methionine metabolism', and 'plant hormone signal transduction' terms. The expression changes of these DEGs were basically consistent with the changes in physio-biochemical characteristics. Overall, AMF alleviated Cd stress in wheat mainly by promoting immobilization and sequestration of Cd, reducing ROS production and accelerating their scavenging, in which the rapid metabolism of GSH may play an important role.

Biostimulants as Innovative Tools to Boost Date Palm (Phoenix dactylifera L.) Performance under Drought, Salinity, and Heavy Metal(Oid)s’ Stresses: A Concise Review

Date palm (Phoenix dactylifera L.) is constantly subjected to abiotic stresses. Hence, the application of biostimulants, such as the arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR), and organic amendments hold tremendous potential to significantly improve the growth and yield of date palm. The strengthening of biostimulants’ main common modes of action is exerted through five main functions: biostimulation (essentially), biofertilization, bioprotection, biological control, and the role of bio-effector. Moreover, synergistic and complementary effects manifest through biochemical and nutritional benefits, in addition to molecular modulation. In this regard, the present concise review focuses on highlighting the beneficial impact of AMF and PGPR, as well as the organic amendments, in boosting the health status and productivity of date palm plants subjected to abiotic stresses. Furthermore, mechanisms reinforcing date palm plants’ resilience to abiotic stresses, powered by biostimulants, are particularly emphasized. Based on this review, we could conclude that the overall findings corroborate the beneficial effects of AMF–PGPR and/or compost and manure application in terms of boosting date palm’s growth traits, development, yielding, as well as soil properties under extreme environmental factors, such as those of drought, salinity, and excessive heavy metal(oid)s. Thus, biostimulants can confer resilience to date palm plants against abiotic stresses.

Sex-specific photosynthetic capacity and Na+ homeostasis in Populus euphratica exposed to NaCl stress and AMF inoculation.

Soil salinity and associated land degradation are major ecological problems. Excess Na+ ions in soil impede the plant photosynthetic process and Na+ homeostasis status. Arbuscular mycorrhizal fungi (AMF) can alleviate salt stress in host plants. Although a number of studies have demonstrated that Na+ accumulation is decreased by mycorrhizae, the molecular mechanisms involved have received little attention from researchers. Populus euphratica is a typical natural woody tree with excellent salt tolerance. Due to its symbiosis forming capability with AMF, we explored the influence of Funneliformis mosseae on the growth, photosynthesis, and expression of three genes involved in Na+ homeostasis within dioecious P. euphratica under salt stress. The results indicated that salt stress significantly increases Na+ contents and inhibits growth status and photosynthetic capacity, especially in females. However, AMF had positive effects on the growth status, photosynthetic capacity and Na+ homeostasis, especially in males. The expression levels of NHX1 in shoots and HKT1 and SOS1 in roots, all of which are involved in Na+ homeostasis, were upregulated by F. mosseae under salt stress. For males, the beneficial effect of AMF centered on extruding, sequestering and long-distance transporting of Na+ ions . For females, the beneficial effect of AMF centered on extruding excessive Na+.

Effect of arbuscular mycorrhizal fungi (Glomus mosseae) and elevated air temperature on Cd migration in the rhizosphere soil of alfalfa

Cadmium (Cd) migration in the rhizosphere soil is easily affected by plants and microorganisms. Global warming significantly affects plant growth, and arbuscular mycorrhizal fungi (AMF) can chelate heavy metals by mycelium, cell wall components, and mycelial secretion. Here, we investigated the regulation of Glomus mosseae on Cd migration in the rhizosphere soil of alfalfa under elevated temperature (ET, + 3 °C). Elevated temperature significantly decreased G. mosseae colonization rate in the roots by 49.5% under Cd exposure. Under ET + G. mosseae + Cd relative to ET + Cd, the contents of free amino acids, total and easily extractable glomalin-related soil protein (GRSP), and root Cd increased significantly; however, the changes in DTPA-Cd in the rhizosphere soil and Cd in the shoots were insignificant. In addition, G. mosseae colonization enhanced the bioconcentration factor of Cd in the roots and the total removal rate of Cd in the rhizosphere soil by 63.4% and 16.3%, respectively, under ET + Cd. However, the changes in the expression of iron-regulated transport 1 (IRT1) and natural resistance-associated macrophage protein 1 genes were insignificant under ET + G. mosseae + Cd relative to ET + Cd. In summary, temperature and G. mosseae significantly affected Cd fate in the rhizosphere soil, and IRT1 gene and rhizosphere soil pH, N, and C/N ratio were significant factors influencing Cd migration. Additionally, G. mosseae improved the remediation efficiency of Cd-contaminated soils by alfalfa under ET. The results will help us understand the regulation of AMF on the phytoremediation of heavy metal-contaminated soils under global warming scenarios.

Use of a RT-qPCR Method to Estimate Mycorrhization Intensity and Symbiosis Vitality in Grapevine Plants Inoculated with Rhizophagus irregularis

Assessing the mycorrhization level in plant roots is essential to study the effect of arbuscular mycorrhizal fungi (AMF) on plant physiological responses. Common methods used to quantify the mycorrhization of roots are based on microscopic visualization of stained fungal structures within the cortical cells. While this method is readily accessible, it remains time-consuming and does not allow checking of the symbiosis vitality. The aim of this work is thus to develop an efficient method for assessing the intensity and vitality of mycorrhiza associated with grapevine through gene expression analyses by RT-qPCR. To this end, grapevine plants were inoculated with the AMF Rhizophagus irregularis (Ri). The relationship between mycorrhization level, assessed by microscopy, and expression of several fungus and grapevine genes involved in the symbiosis was investigated. In AMF-inoculated plants, transcript amounts of fungal constitutively-expressed genes Ri18S, RiTEF1α and RiαTub were significantly correlated to mycorrhization intensity, particularly Ri18S. Grapevine (VvPht1.1 and VvPht1.2) and AMF (GintPT, Ri14-3-3 and RiCRN1) genes, known to be specifically expressed during the mycorrhizal process, were significantly correlated to arbuscular level in the whole root system determined by microscopy. The best correlations were obtained with GintPT on the fungal side and VvPht1.2 on the plant side. Despite some minor discrepancies between microscopic and molecular techniques, the monitoring of Ri18S, GintPT and VvPht1.2 gene expression could be a rapid, robust and reliable method to evaluate the level of mycorrhization and to assess the vitality of AMF. It appears particularly useful to identify AMF-inoculated plants with very low colonization level, or with non-active fungal structures. Moreover, it can be implemented simultaneously with the expression analysis of other genes of interest, saving time compared to microscopic analyses.

The Importance of Mycorrhizal Fungi in the Development and Secondary Metabolite Production of Echinacea purpurea and Relatives (Asteraceae): Current Research Status and Perspectives

The cultivation of Echinacea purpurea for commerce and obtaining high-quality plant material on a large scale remain a challenge for growers. Another challenge for the following decades is to create sustainable agriculture that meets society’s needs, has no environmental impact, and reduces the use of fertilizers and pesticides. The aims of this overview were: (1) to present the importance of the chemical compounds reported in E. purpurea; (1) to synthesize results about cultivation of the E. purpurea with arbuscular mycorrhizal fungi (AMF) and associated microorganisms; (2) to exemplify similar research with plants from the Asteraceae family, due to the limited number of published Echinacea studies; (3) to collect recent findings about how the inoculation with AMF affects gene expressions in the host plants; (4) to propose perspective research directions in the cultivation of E. purpurea, in order to increase biomass and economic importance of secondary metabolite production in plants. The AMF inocula used in the Echinacea experiments was mainly Rhizophagus irregularis. The studies found in the selected period (2012–2022), reported the effects of 21 AMFs used as single inocula or as a mixture on growth and secondary metabolites of 17 plant taxa from the Asteraceae family. Secondary metabolite production and growth of the economic plants were affected by mutualistic, symbiotic or parasitic microorganisms via upregulation of the genes involved in hormonal synthesis, glandular hair formation, and in the mevalonate (MVA), methyl erythritol phosphate (MEP) and phenylpropanoid pathways. However, these studies have mostly been carried out under controlled conditions, in greenhouses or in vitro in sterile environments. Since the effect of AMF depends on the variety of field conditions, more research on the application of different AMF (single and in various combinations with bacteria) to plants growing in the field would be necessary. For the identification of the most effective synergistic combinations of AMF and related bacterial populations, transcriptomic and metabolomic investigations might also be useful.

Response of Capsicum annuum L. Seedlings Raised in Pro Trays to Inoculation with AM Fungus Glomus bagyarajii and K Solubilizing Bacterium Frateuria aurantia

Raising vegetable seedlings in pro trays is becoming an innovative approach to producing quality seedlings in horticulture. The present investigation was conducted to evaluate the effect of arbuscular mycorrhizal fungus (AMF) Glomus bagyarajii and potassium (K) solubilizing bacterium Frateuria aurantia singly and together in enhancing the growth of capsicum seedlings raised in pro trays under polyhouse conditions. Different growth parameters such as shoot and root length, total seedling length, stem diameter, dry weight of seedlings, biovolume index, plant strength, vigour index, macro and micronutrient uptake, mycorrhizal root colonization, and the population of F. aurantia in the root zone soil were monitored. Significantly higher shoot length, root length, stem diameter, and biovolume index were recorded in the treatments inoculated with G. bagyarajii alone, followed by F. aurantia alone. Most of the plant growth parameters were significantly less in the dual inoculated treatment with G. bagyarajii + F. aurantia compared to single inoculation with either of them. This brings out the negative influence of the two inoculants on each other leading to a reduced effect on plant growth.