Number Of Arbuscular Mycorrhizal Fungi Spores Research Articles

Micorrizas arbusculares em pomares de mangueira no semiárido brasileiro: influência da fenologia, do manejo e da variedade

ABSTRACT: Arbuscular mycorrhizal fungi (AMF) increase the absorption surface of roots, providing greater absorption of water and nutrients from the soil by plants. Thus, it is important to know how arbuscular mycorrhizae are affected by factors such as phenology, management and varieties in mango (Mangifera indica) orchards in the irrigated semi-arid region. With this objective, soil and root samples were collected during the vegetative, flowering and fruiting stages, and in the water stress period before flowering, always on the same trees. The study was carried out in mango orchards of the Keitt and Palmer varieties, in agricultural farms located in Juazeiro - BA and Petrolina - PE, both under conventional management (with fertilizers and paclobutazol). The soil was used to quantify the number of AMF spores and phosphorus content. Mycorrhizal colonization in roots was evaluated in qualitative terms (presence of hyphae, vesicles and arbuscles) and quantitative terms (% of colonization). Total mycorrhizal colonization was high, with averages above 65%, and higher values in the fruiting period. Colonization by vesicles and arbuscles was on average above 45% and 17%, respectively, with higher means also during fruiting. The number of AMF spores in the soil averaged over 130 spores in 50 g of soil, with higher values in the period of water stress. The phosphorus content in the soil did not influence mycorrhizal colonization and the number of spores in the soil. The association of AMF with mango trees was generally affected by management and phenology, regardless of the cultivated varieties.

The Effect of Pruning and Growing Media Composition on Arbuscular Mycorrhizal Propagation

The symbiosis of arbuscular mycorrhizal fungi with plants is the oldest symbiosis in the world. The obligate nature of mycorrhizal fungi in symbiotic relationships is believed to underlie its enduring presence to this day. The application of arbuscular mycorrhizal fungi (AMF) based fertilizers has become increasingly common. Spores are the most important organs that determine the quality of AMF-based fertilizers, along with AMF colonization in the roots. The production of AMF spores is greatly influenced by plant physiology, including photosynthesis processes affected by canopy abundance, as well as the type of planting medium, which determines plant root growth and AMF habitat. This study was conducted to investigate the effect of pruning and planting medium composition on AMF infection and spore production in AMF propagation using sorghum as the host plant. The pruning levels tested were at one, two, and three months after germination, and thereafter, each plant was maintained for 136 days after planting (DAP). The tested planting medium composition was the ratio between zeolite and compost in five different compositions: (v/v) 1) 100:0, 2) 90:10, 3) 70:30, and 4) 50:50. The chemical characteristic of compost used was contained 15.5% C, 1.49% N, 2.54% P2O5, 1.49% K2O, pH 6.6, and some microelements such as Cr, Fe, Zn, and Mn at 5.2 ppm, 5961 ppm, 294 ppm, and 199 ppm, respectively. The Sukabumi‘s zeolite used had a size of 2-3 mm. Propagation of AM fungal spores was carried out using polybags containing 10 kg of medium according to the treatment. Plant maintenance was carried out by alternating between watering with water and Johnson nutrient solution. Watering was performed until the plants were 120 days old, and subsequently, no watering was done until 136 days after planting. The observed parameters were the development of AMF spore numbers until a 4.5-month incubation period. The results showed that pruning time can affect spore production if the plant has reached a certain vegetative age, which is three months for sorghum. Additionally, adding 10% compost to zeolite medium can enhance spore formation, even though sorghum growth may not be at its maximum in this medium composition.

A New Technique for the Extraction of Arbuscular Mycorrhizae Fungal Spores from Rhizosphere.

Monitoring the dynamics of the spore bank of arbuscular mycorrhizal fungi (AMF) is essential for the sustainable management and protection of agroecosystems. The most common method for extracting AMF spores from soil is the wet-sieving technique (WST). However, this method has many disadvantages. In this study, we modified the WST using new approaches: the ultrasound wet-sieving technique (UWST) and the ultrasound centrifuge technique (UCT). We enumerated and compared the numbers and quality of spores obtained from WST, UWST, and UCT to validate the new modified techniques. We extracted AMF spores from the rhizospheres of different plants, including wheat (Triticum aestivum L.), bean (Phaseolus vulgaris L.), tomato (Solanum lycopersicum L.), pepper (Piper nigrum L.), parsley (Petroselinum crispum Mill.), and turfgrass (Lolium perenne L.) collected from the Van Lake basin, Turkey. The highest and lowest AMF spore numbers were observed in wheat and turfgrass rhizospheres. The UCT allowed for the extraction of the highest number of spores from all rhizospheres, followed by the UWST and WST. The UWST and WST allowed for the extraction of similar spore numbers from wheat, pepper, parsley, and turfgrass rhizospheres. Beyond the high extracted spore number, UCT was shown to be a fast and low-material-consuming approach. These findings demonstrate that the UCT can be used to efficiently extract AMF spores in future research.

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

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

Modulating of arbuscular mycorrhizal fungi spores by collaboration between soil fauna ecosystem engineers and biochar

Soil fauna as ecosystem engineers and biochar play a role in spore modulating of arbuscular mycorrhizal fungi (AMF). This study aims to analyze the effect of the soil fauna and biochar dosage on the AMF spore in abundance and diversity, and to investigate infection presence of AMF to maize roots grown in modified soil. Sixteen combinations of the soil fauna and biochar dosage in 1.5 kg of soil were tested. The abundance, genus richness, Shannon indices, and Simpson indices of AMF spore counted at 4, 6, and 8 weeks after treatment. Maize grown in different pots filled with 100 g of soil from each treatment, and root infection using aniline blue staining observed after 28 days of rearing. The results showed the total spore produced with 15 Pheretima sp. + 15 Ponera sp. and 50 g of biochar was the highest, while the treatment without ecosystem engineers and 150 g of biochar produced the fewest. Furthermore, genus richness with 15 Pheretima sp. + 15 Ponera sp. and without biochar was the richest, while the treatment without ecosystem engineers and 150 g biochar was the poorest. Maize grown on soils treated with ecosystem engineers and biochar dose up to 50 g sustained life, while the 100 g and 150 g treatments did not, as roots infected with the mycorrhizal. Based on the results, the soil fauna and biochar dosage to some extent increased the number of AMF spores and created a suitable soil environment for growth and AMF infections to maize roots.

Enumerating Indigenous Arbuscular Mycorrhizal Fungi (AMF) Associated with Three Permanent Preservation Plots of Tropical Forests in Bangalore, Karnataka, India

The establishment of Permanent Preservation Plots (PPPs) in natural forests has a signifi-cant role in assessing the impact of climate change on forests. To pursue long-term studies on cli-mate change, PPPs were established during the year 2016 in two major forest areas in Bangalore to conduct ecological studies to monitor the vegetation changes. One of the objectives of the study was to understand the drivers of diversity, such as soils, in terms of nutrients and physical and biological properties. The native tropical forest of Bangalore, which houses Bannerghatta National Park (BNP) on the outskirts, is relatively underexplored in terms of its microflora, particularly arbuscular my-corrhizal fungi (AMF). Hence, the present study was aimed at the quantitative estimation of arbus-cular mycorrhizal fungi (AMF) in the three 1-ha PPPs which were established in Bannerughatta National Park (BNP) and Doresanipalya Reserve Forest (DRF) as per the Centre for Tropical Forest Sciences (CTFS) protocol. In BNP, two plots were established, one in the Thalewood house area (mixed, moist, deciduous type) and the other in the Bugurikallu area (dry, deciduous type). In DRF, one plot was established in dry, deciduous vegetation. Each one-hectare plot (100 m × 100 m) was subdivided into twenty-five sub-plots (20 m × 20 m). Composite soil samples were collected during two seasons (dry and wet) and analyzed for AMF spore and available phosphorus (P) content. The results revealed the presence of AMF in all the three plots. Doresanipalya plo had the highest spore number, followed by the Bugurikallu plot and Thalewood house plot. The available phosphorous and AMF spore numbers showed correlations in all the three plots. Among the AMF spores, the Glomus species was found to dominate in all the three plots. The study shows that the dry, decidu-ous forests accommodated more AMF spores than the mixed, moist forests.

Study of Arbuscular Mycorrhizal Fungi population in the rhizosphere of oil palm planted on 4 different soil types in Central Kalimantan Indonesia

Arbuscular mycorrhizal fungi (AMF) are naturally found in the soil. The population of this fungus is influenced by environmental factors such as soil type. Different soil types have different characteristics and will affect the AMF population in the soil. Therefore, this study was carried out to determine the AMF population in the soil based on the number of spores in the rhizosphere of oil palm planted in 4 different soil types, namely Dystrudepts, Paleudults, Haplohumods, and Haplosaprists. Soil samples were taken from each soil type at 4 sample points. At each sample point, soil samples were taken from 5 adjacent oil palm trees. Rhizosphere soil samples were taken at 4 points inside the oil palm circle at a depth of up to 15 cm and 4 points from the outside and then composited to represent 1 sample point for inside and outside the circle. Extraction of AMF spores from soil samples was carried out by the wet sieving method. The results showed that the average number of AMF spores per 50 g of rhizosphere soil from inside and outside the oil palm circle were 66,7 and 53,5 spores for Dystrudepts, 115,5 and 91,5 spores for Paleudults, 27 and 71,8 spores for Haplohumods, and 83,3 and 55 spores for Haplosaprists respectively. In Dystrudepts, Paleudults, and Haplosaprists soil types, the number of spores in the rhizosphere of oil palm inside the circle was higher than outside. On the other hand, for Haplohumods soil types, the number of spores inside the circle was lower than outside the circle.

Crecimiento de albahaca (Ocimum basilicum L.) ‘Sweet Nufar’ inoculada con hongos micorrícicos arbusculares y Azospirillum brasilense

The use of beneficial microorganisms in agriculture can increase the productivity of agricultural crops; however, there are few studies that consider aromatic plants, such as basil (Ocimum basilicum L.). The aim of this study was to evaluate the growth of 'Sweet Nufar' basil inoculated with arbuscular mycorrhizal fungi (AMF) and Azospirillum brasilense. The treatments tested were: 1) without microorganisms (control), 2) Rizhophagus intraradices, 3) Funneliformis mosseae, 4) AMF consortium, 5) Azospirillum brasilense, 6) R. intraradices + A. brasilense and 7) without microorganisms and irrigated with 100 % Steiner's nutrient solution. Treatments 1 to 6 were irrigated with the same nutrient solution, but at 50 %. Fifty days after transplanting, growth variables, mineral concentration, colonization percentage and number of AMF spores were recorded. The AMF and A. brasilense bacterium increased the fresh biomass weight and leaf area of 'Nufar' basil, which was associated with the highest concentration of nitrogen and potassium in the plant tissue. This implies that the microorganisms evaluated increase the development and growth of basil grown with reduced levels of mineral nutrition, which represents a sustainable alternative in the agronomic management of this crop under greenhouse conditions.

Diversity and Benefits of Arbuscular Mycorrhizae in Restored Riparian Plantations

Due to the increasing use of vegetation for fuel wood, cattle, agriculture, and due to population pressure that negatively affects biodiversity values, more plantations are needed to obtain a permanent vegetal cover. Attention has been paid to microbial interactions (arbuscular mycorrhizae (AM)) for management and inoculation. To evaluate the benefits of inoculation, the root colonization of inoculated seedlings, soil aggregation, and arbuscular mycorrhizal fungi (AMF) diversity were examined by two field treatments (fertilized with organic matter (OM) vs. fertilized with natural rock phosphate (P)). The preserved and experimental areas presented higher AMF spore number and richness (nine species) than the degraded areas. The addition of OM or P did not improve root colonization by AMF; however, it was a guarantee for a successful restoration as, in the restored fields, a high soil aggregation was found, in addition to a high root colonization, spore number, and richness of AMF. However, the undisturbed site presented the more prominent values. This study showed that AMF are important components in riparian areas, and it brings information for inoculant production in ecological restoration using mixed plantations, contributing to the establishment of mycorrhizal vegetation and soil aggregation that not only benefit AM plants, but also allow non-host plants in degraded areas.

Production of Arbuscular Mycorrhizal Fungi Spores (AMF) Glomus Coronatum and Glomus Claroideum With Ab Mix Nutrition

Arbuscular Mycorrhizal Fungi (AMF) is an obligate fungus that has a symbiosis with plant roots and can stimulate plant growth and productivity so that AMF has the potential to be developed as a biological fertilizer. AMF propagation is influenced by many factors including fertilization. This study aims to determine the effect of giving AB mix nutritional doses on the production of AMF types of Glomus coronatum and Glomus claroideum. The research was conducted at the Plastic House of the Indonesian Mycorrhizal Association Southeast Sulawesi Branch and the Laboratory of the Department of Forestry, Faculty of Forestry and Environmental Sciences, UHO in September - December 2022 using a factorial Completely Randomized Design (CRD) with two factors, namely the first factor was AMF type including Glomus coronatum and Glomus claroideum and the second factor is AB mix nutrition including control, 2.5 ml/1000 ml water, 5 ml/1000 ml water. The results showed that the interaction treatment of AMF Glomus claroideum and the provision of 2.5 ml AB ​​mix nutrition increased the number of AMF spores by 35 spores/5 g zeolite and root colonization by 69.16%.

Identifikasi Fungi Mikoriza Arbuskula (FMA) pada Mangga Lokal Indramayu

Mango (Mangifera indica L.) is one of Indonesia's leading horticultural commodities. The island of Java is the national center for mango production. Mango production in West Java is one of the largest in Indonesia. The Indramayu region is the largest mango production center in West Java. Demand for this commodity is increasing, especially exports, while mango production in the last five years has fluctuated. The way to maintain optimal and sustainable mango production is by using fertilization. One of the fertilization efforts that can be done is with Arbuscular Mycorrhizal Fungi (AMF). The presence of AMF in host plants can help the uptake of nutrients, especially phosphorus which is very important in growth, especially in the generative phase of plants. However, not all AMF can be symbiotic with plants. Therefore, it is necessary to explore and identify AMF for its utilization. This study aimed to obtain information on the diversity of AMF in local mangoes from Indramayu. This research was conducted in Jatibarang District, Indramayu with a research time of 12 months and started after the rainy season. The results showed that two AMF genera were found in the local mango rhizosphere of Indramayu, namely the genus Glomus and Acaulospora. The number of AMF spores found per 20 g of soil was 37.67 in Lobener Village, 31.67 in Jatisawit Village, and 42.33 in Krasak Village. AMF colonization in Lobener Village was 34.44%, Jatisawit Village 23.33%, and Krasak Village 33.33%.

Experimental assessment of forest floor geophyte and hemicryptophyte impact on arbuscular mycorrhizal fungi communities

PurposeHerbaceous plants are important components of temperate forest structure and its functioning, however, their impacts on arbuscular mycorrhizal fungi (AMF) remain largely unexplored. We studied the influence of forest herbaceous plant species on AMF abundance, morphospecies richness, and community composition in soil.MethodsWe tested the influence of plant species identity in an outdoor mesocosm experiment, using two soils, differing in physicochemical properties, planted with four plant species of contrasting traits related to morphology, phenology, reproduction, and ecology; the hemicryptophyte, summer-green Aegopodium podagraria, and spring ephemeral geophytes comprising Allium ursinum, Anemone nemorosa, and Ficaria verna. The plants were grown on both soils in four monocultures, in a combination of A. podagraria and A. ursinum, and a mixture of all four species.ResultsAegopodium podagraria and A. ursinum promoted AMF abundance and diversity the most. Higher AMF root colonization and/or soil concentrations of AMF structural and storage markers 16:1ω5 PLFA and NLFA, as well as higher AMF spore and morphospecies numbers were found in the A. podagraria and A. ursinum monocultures and mixture. The short period of photosynthetic activity of A. ursinum due to rapid leaf decay does not negatively affect the symbiosis with AMF. Although A. nemorosa and F. verna are mycorrhizal, their effect on AMF in soil was weak.ConclusionsThe plant impact on AMF may be related to the differences in plant coverage and the character of their interactions with AMF. The herbaceous plants can form niches in soil differing in AMF abundance and diversity.

Arbuscular Mycorrhizal Fungi and Soil Quality Indicators in Eucalyptus genotypes With Different Drought Tolerance Levels.

Silviculture has great importance worldwide, and the use of Eucalyptus species, which account for 75% of the local planted forest in Brazil, is one of the factors that contributes to the success of this activity in the country. Despite its adaptability, the yield of Eucalyptus is often affected by climate change, particularly water deficiency. Plants have developed strategies to mitigate water stress, for example, through their association with mycorrhizal fungi. The genus Eucalyptus, particularly in the plant domain, establishes symbioses with arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (ECMF). The influence of Eucalyptus species on AMF and soil quality indicators is not well understood. Our aim was to conduct a preliminary evaluation of the various responses of soil AMF communities and soil nutrient dynamics in the presence of Eucalyptus species with different degrees of drought tolerance. A field experiment was established containing six Eucalyptus species, E. brassiana, E. camaldulensis, E. citriodora, E. cloeziana, E. grandis, and E. urophylla, all of which were planted in large plots. Soil and root samples were taken when the plants were 1.7 and 2.2 years old. We found that Eucalyptus species with low (E. grandis and E. urophylla) and intermediate drought tolerance (E. citriodora and E. cloeziana) showed stronger correlations with the AMF community than Eucalyptus species with high drought tolerance (E. brassiana and E. camaldulensis). Differences were also found between Eucalyptus species for AMF spore numbers and root colonization percentages, which was most evident for E. urophylla. The microbiological attributes found to be most responsive to Eucalyptus species were soil enzyme activities, AMF spore numbers, root colonization percentages, and fungal abundance. Soil organic carbon, phosphorus, potassium, zinc, copper, and iron were the main chemical drivers related to the soil AMF community structure in the presence of E. brassiana.

Soil Characteristics and Arbuscular Mycorrhizal Fungi from Different Pasture Types: A Case Study in the Western Black Sea Region, Turkey.

This research was conducted to compare the soil characteristics and arbuscular mycorrhizal fungi (AMF) spore density from different types of pastures. To this purpose, four different areas were selected including an artificial pasture (AP), a fertilized artificial pasture (FAP), a natural pasture (NP), and a fertilized natural pasture (FNP). From the spring period of 2008, urea has been used as a fertilizer at an annual rate of 5kg/da. Different numbers of AMF spores were found in all soil samples taken from the artificial and natural pastures. The average numbers of AMF spores in 50g of soil from the AP, the FAP, the NP, and the FNP were determined as 266.9, 125.3, 117.0, and 59.6, respectively. Both the number of AMF spores and the number of species were found to be lower in the fertilized pastures, and consequently, it was concluded that the urea fertilizer had reduced the number of AMF spores and species. Spores were identified according to their morphological characteristics. In all pastures, the study identified 25 different AMF species belonging to 11 genera from 7 families. Rhizoglomus aggregatum was classified as the dominant species in FNP soils. Acaulospora dilatata, A. laevis, Dentiscutata heterogama, Diversispora eburnea, Gigaspora albida, G. margarita, Claroideoglomus etunicatum, C. lamellosum, Funneliformis caledonium, Glomus hoi, Rhizoglomus clarum, R. irregulare, Sclerocystis sinuosa, and Ambispora gerdemannii were classified as rare species in all pastures. This study demonstrated a negative correlation between the AMF spore density and the soil organic carbon, total nitrogen, and available potassium.

Early Growth Performance of In Vitro Raised Melia volkensii Gürke Plantlets in Response to Beneficial Microorganisms under Semi-Arid Conditions.

Before in vitro propagated Melia volkensii plants can be used for mass planting, the transition phase to in vivo conditions needs to be better controlled because too many plants are lost during acclimatization and in the field. Two experiments were set up to evaluate the effects of biological agents on the establishment of M. volkensii in vitro plantlets. The biological agents consisted of Trichotech®, Bio-cure B®, Rhizatech®, Bacillus subtilis, a Trichoderma isolate and self-isolated native arbuscular mycorrhizal fungi (AMF). Regarding the latter, in soil from the nursery, the number of AMF spores increased from six spores to 400 per 100 g of soil using a trap culture, in which thirteen AMF morphotypes were identified and root colonization assessed through observation of hyphae, vesicles, coils and appressoria. The first experiment was set up in the greenhouse to investigate the efficacy of the biological agents on the hardening off. In the second, a field experiment was set up to study their effect on the early establishment of the plantlets in the field compared to seedlings. All biological agents significantly (p ≤ 0.05) improved in vitro plant survival and growth compared to the control. The highest plant height and number of leaves per plant were recorded in plants treated with Rhizatech®, Native AMF, Bio-cure B® and Trichoderma isolate. The treatments with Rhizatech®, Bio-cure B® and native mycorrhiza recorded a significantly wider stem. The root diameter of the plants treated with Rhizatech® and Bio-cure B® was the largest, but the plants inoculated with the native AMF had the longest roots. Moreover, the inoculated plants generally developed multiple secondary roots. After two months, AMF had clearly colonized the acclimatized plantlets. In the field experiment, the biologicals made no difference in survival rate but did produce a significantly larger leaf area after two months, with the largest leaves recorded with Rhizatech®, native AMF and Trichotech®. They also increased the quality index of the plants from 0.21 to 0.52. The performance of in vitro grown M. volkensii plants six months after planting in semi-arid conditions in Kiambere was better than that of seedlings. Inoculation of plants increased plant height and diameter. Thus, inoculation of biological agents is an efficient approach for improving the early growth of in vitro propagated M. volkensii plants.

Short Communication: Occurrence of arbuscular mycorrhizal fungi associated with Casuarina equisetifolia in saline sandy environment, North Sumatra, Indonesia

Abstract. Delvian, Hartanto A. 2022. Short Communication: Occurrence of arbuscular mycorrhizal fungi associated with Casuarina equisetifolia in saline sandy environment, North Sumatra, Indonesia. Biodiversitas 23: 2520-2525. Arbuscular mycorrhizal fungi (AMF) form a mutualistic association with plant roots to cope in the extreme environments including the saline and sandy soils in the coastal areas. In this study, the occurrence of AMF associated with Casuarina equisetifolia that has been planted for coastal rehabilitation located at Cermin Beach, North Sumatra was investigated including its abiotic-biotic interactions from topsoils (0-20 cm) to subsoils (20-80 cm). A total of 10 AM fungal morphotypes were documented with Glomeraceae as the dominant AM fungal taxa (9 morphotypes) and a Glomoid morphotype exists in all soil depths. The number of AMF spores decreased as soil depth increased following other environmental conditions such as pH, soil P availability and soil moisture based on the result of Pearson’s correlation test. The results showed a moderate-to-low level of biodiversity of AMF based on Shannon’s diversity index. The findings revealed the vertical distribution of AMF in a saline environment and supported the planting of C. equisetifolia which successfully recruited the indigenous AMF to form a symbiosis to thrive in the stressful environment.

Effects of ultramafic topsoil stockpiling during mine activities on its microbial diversity and other microbiological and physicochemical characteristics

Nowadays, ecological restoration is considered the best solution for the rehabilitation of mining-degraded areas, particularly when it concerns valuable ecosystems. This is the case in New Caledonia, a hot spot of biodiversity, with 82% of endemic plant species in ultramafic soils. The use of topsoil to restore mined areas is an important practice. However, topsoil stockpiling can reduce soil fertility. We studied the evolution of different properties of two topsoils stored in 10 m height piles on mined areas, in order to characterize possible degradations. The effects of storage duration, depth, and topsoil origin were analyzed, focusing mainly on bacterial and fungal diversity assessed after bar-coded pyrosequencing, and expressed by operational taxonomic units (OTU). Microbial activity (carbon dioxyde production), arbuscular mycorrhizal fungi (AMF) spore numbers, bulk density and different other physicochemical characteristics were also determined. The studied ultramafic soils were characterized by a relatively high microbial diversity with 45 bacterial phyla and 7 fungal phyla. Bacterial and fungal OTU numbers did not vary significantly after 12 months of storage, but the community structures of these groups were changed. AMF diversity was significantly reduced by the storage. Microbial activity, AMF spore numbers, soil organic carbon, total nitrogen, cation exchange capacity, and carbon to nitrogen ratio (C/N) decreased significantly starting from 3 to 9 months of topsoil storage. In contrast, soil bulk density and pH increased, and extractable concentrations of potentially toxic metals varied only slightly. All the changes induced by topsoil stockpiling in microbial population structure, AMF diversity, and other biotic and abiotic traits may negatively affect soil functions and create perturbations of the reconstructed ecosystems after revegetation. It is then necessary to reduce the storage of ultramafic topsoils as far as possible. In all cases, the stockpiling should not exceed six months before its use in ecosystem restoration. It is also recommended to reduce the height of the stockpiles, when possible, to 1 m or less to minimize the compaction and the anaerobiosis.

Wildfire does not affect spore abundance, species richness, and inoculum potential of arbuscular mycorrhizal fungi (Glomeromycota) in ferruginous Canga ecosystems

Canga ecosystems develop over superficial iron crusts with shallow and nutrient-poor soils. Under these conditions, arbuscular mycorrhizal fungi (AMF) play an important role in helping plants to overcome abiotic and biotic stresses. Canga can suffer periodic burning and yet it is unknown what the impacts of fire are to AMF communities. We aimed to compare AMF in Canga areas affected by burning (BC) with those with no previous history of burning (NC). We compared AMF species composition, spore numbers, species richness, and mycorrhizal inoculum potential. The total number of spores, AMF species richness and mycorrhizal colonization measured in the infectivity bioassay were not significantly different between areas. A total of 23 species in 10 genera were recovered, with most species belonging to Gigasporaceae and Acaulosporaceae. BC and NC shared 52 % of AMF species. Gigaspora albida, Gigaspora gigantea, and Dentiscutata heterogama sporulated exclusively in trap cultures. We concluded that AMF spore communities were not affected by burning in Canga soils as measured by spore abundance, species richness and infectivity. Our data contribute to the inventory of soil biodiversity associated with Canga, a high biodiverse and threatened Brazilian ecosystem.

Occurrence and richness of arbuscular mycorrizal fungi in vineyards with grapevine decline and dieback symptoms

ABSTRACT: This research identified arbuscular mycorrhizal fungi (AMF) in rhizosphere soil of grapevines with Grapevine Death and Decline symptoms (GDD) or asymptomatic healthy (H) plants, and characterized the relationship of AMF communities with soil chemical attributes. The AMF spore number ranged from 287 to 432 spores 50 cm-3 in soil with GDD plants, and from 357 to 464 spores 50 cm-3 in H plants, with no differences among vineyards or between GDD and H plants within each vineyard. We detected 42 species and 17 genera, and most taxa belonged to Acaulosporaceae or Glomeraceae. Claroideoglomus etunicatum, Funneliformis mosseae, and Archaeospora trappei were the most frequent species in all vineyards. Soil chemical attributes were not determinant for the occurrence of most fungal species; although, Entrophospora infrequens, Diversispora sp1 and Diversispora sp2 were associated with a vineyard having high soil copper. Vineyards harbor highly diverse AMF communities, which are determined by location.

Fungal root colonization and arbuscular mycorrhizal fungi diversity in soils of grasslands with different mowing intensities

Grasslands are among the most dynamic and threatened plant communities, largely due to their dependence on management that has changed in recent decades. The intensity of human-induced disturbances (primarily removal of plant biomass by various methods) has decreased, leading to changes in plant species composition and declines in plant diversity in these communities. So far, no studies have shown how mowing affects fungal communities in both roots and soils and their relation with plant community parameters and soil chemical properties in different grassland types. We thus compared the impact of mowing intensity (low, moderate, high) on root colonization by common root-inhabiting fungi, namely arbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE), and Olpidium spp., as well as on AMF spore number, species richness and composition in soils for three seasons (spring, summer, autumn), in grasslands differing in soil moisture (wet, moderately wet, and dry). Mowing intensity had no effect on the fungal root colonization. The number of AMF spores and species, and AMF species composition did not differ between types of management as well. However, most of the fungal parameters in roots and soils varied across the types of grassland and/or seasons. Our results suggest that AMF, DSE, and Olpidium spp. colonization of plants as well as AMF diversity in soils in the studied grasslands are resilient to the mowing disturbance. This may be due to the low impact of the management on plant species richness and soil chemical properties, as well as the adaptation of these fungal communities to recurrent human-induced disturbances in semi-natural habitats.