Root Colonization Rate Research Articles

Effect of drought and season on arbuscular mycorrhizal fungi in a subtropical secondary forest

Arbuscular mycorrhizal (AM) fungi in both soil and roots were examined in May (summer) and December (winter) under a 4-y drought experiment in a Chinese subtropical secondary forest. Drought significantly decreased AM fungal extra-radical hyphal density, spore density, and root colonization rate in both seasons. These AM parameters were significantly higher in summer than in winter in the control treatment, but only AM fungal extra-radical hyphal density exhibited the same seasonal trend in the drought treatment. In total, 45 AM fungal operational taxonomic units (OTUs) were obtained at a 97% sequence similarity level using Illumina sequencing of 18S rDNA. Drought and season had no significant effects on AM fungal OTU richness in soil and roots. AM fungal community composition in soil and roots was significantly affected by season but not by drought. This finding enhances our understanding of the response of AM fungi to global climate change in subtropical forest ecosystems. • AM fungal abundance was decreased by drought in both seasons. • AM fungal richness was not affected by drought or season. • AM fungal community composition was influenced by season but not by drought.

Spore diversity of arbuscular mycorrhizal fungi in human‐modified neotropical ecosystems

AbstractNeotropical landscapes are diverse mosaics of ecosystems commonly resulting from different degrees of human intervention. Although easily recognized by their vegetation, the associated soil microbiota including arbuscular mycorrhizal fungi (AMF) is little known. In Mexico, native tropical rainforest and native savannas are rapidly vanishing, remaining in few spots surrounded by human‐made ecosystems. It is unknown, however, how such vegetation types differ in their AMF communities. We compared the spore diversity, spore density and root colonization by AMF in contiguous mosaics of tropical rainforest, savanna and two pine plantations, one managed and the other unmanaged. We detected indicator species associated with tropical rainforest. The savanna displayed the highest values of root colonization of AMF and the lowest spore density. Conversely, the highest spore density and the lowest root colonization rates were found in the tropical rainforest. The two pine plantations showed intermediate values of spore density and colonization between tropical rainforest and the savanna. We did not detect significant seasonal differences (between dry and rainy seasons) in AMF species richness, spore density and root colonization within the vegetation types (except for root colonization in the savanna). Soil cation exchange capacity, phosphorus and nitrogen were negatively associated with AMF spore density and species richness. Our findings suggest that contiguous vegetation types in neotropical landscapes may display significant differences in AMF species composition, spore density and root colonization, and that such differences can be explained in part by soil properties and levels of human intervention.

Origanum syriacum Essential Oil Chemical Polymorphism According to Soil Type.

Background: Origanum syriacum L. is an aromatic plant growing wild in Lebanon. This species is highly used in Lebanese traditional medicine and is a staple food in Lebanese gastronomy. Due to the over-harvesting, this species has become a cultivated crop rather than being collected from the wild. This study aims to evaluate the chemical polymorphism according to soil type. Methods: Plant samples were cultivated in different soil types including manure, potting mix, professional agriculture mixture, vegetable compost, nursery soils, and natural agricultural soil inoculated with arbuscular mycorrhizal fungi. After 16 weeks of culture, fresh shoot biomass was measured. Root colonization rate was evaluated and foliar biomasses were used for essential oil (EO) extraction. EO yield was calculated and the identification of the main chemical compounds of EO samples was performed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC/MS). Results: Our findings revealed that the soil type affects the O. syriacum chemotype. Indeed, the EO samples could be divided into two groups: thymol chemotype group including manure and vegetable compost soils and non-sterilized non-inoculated EO samples, and the thymol/carvacrol chemotype including potting mix, professional agriculture mixture, nursery mixture, sterilized non-inoculated, non-sterilized inoculated, and sterilized inoculated EO samples. These results showed that manure and vegetable compost soils promoted thymol synthesis, whereas potting mix, professional agriculture mixture, and nursery mixture soils were thymol/carvacrol chemotype. Moreover, mycorrhizal inoculation increased carvacrol and reduced thymol productions in comparison to non-inoculated conditions. Additionally, mycorrhizal inoculation showed significant enhancements in mycorrhizal rates and shoot biomass production with respect to the non-sterilized soil. Conclusions: These variations confirm the influence of the edaphic conditions on the chemical components biosynthesis pathways of oregano plants. The results of this investigation could be used for determining optimal soil type, leading to a good quality herb production.

Arbuscular mycorrhizal fungal communities in soils under three phytophysiognomies of the Brazilian Atlantic Forest

ABSTRACT Arbuscular mycorrhizal fungi (AMF) play an important role in plant community productivity and structure, and so studying the factors that affect the diversity and structure of this fungal community is important for understanding their ecology in tropical forests. We investigated AMF spore communities and root colonization under three forest phytophysiognomies (Restinga Forest, REF; Lowland Ombrophilous Dense Forest, LLF; and Montane Ombrophilous Dense Forest, MTF). Spore abundance was lowest in LLF and highest in REF, with no statistical differences relative to MTF. Spore diversity indices and root colonization rates were not statistically different among the phytophysiognomies. However, principal components analysis revealed that AMF community structure differed according to forest phytophysiognomy. Hierarchical partitioning analysis indicated that most of the AMF community variables were better explained by phytophysiognomy than by chemical and physical attributes of the soil. In addition to the plant community, clay content, pH, Boron, P, S and CEC best explained some of the AMF community variables. Thus, we conclude that while several factors determine AMF community structure in the Atlantic Forest, phytophysiognomy is the most significant.

Endophytic Fungal Root Colonization of Eragrostis tef in Eroded Croplands of the Ethiopian Highlands Is Limited by Low Spore Density and Fertilisation

Eragrostis tef (teff) is a (sub-)tropical cereal crop and a staple food in Eastern Africa. As soil erosion has become increasingly worse in the Ethiopian highlands, we test the hypotheses that (1) eroded soils possess low arbuscular mycorrhizal fungi (AMF) spore densities, (2) teff growth is limited by low endophytic fungal root colonization rates and (3) colonization rates and spore densities are additionally reduced by fertilization. A pot experiment was set up to study the effect of cropland soil inoculation using pristine fungal communities (from adjacent forests) or fertilization. AMF spore densities in soil with and without teff and root colonization by AMF and dark septate endophytes (DSE) were related to straw and grain yields. AMF and DSE colonization rates were higher after inoculation, which provides evidence that a low spore density limits teff root colonization in eroded soils. However, teff yields were significantly increased after fertilisation but not inoculation. N-P fertilization further lowered root colonization rates and spore density. We conclude that forest soils serve as a refugium for soil biota in the degraded landscape of the Ethiopian highlands. As both increased AMF and DSE increase the stress resistance of plants, their inoculation potential should be considered when developing sustainable management methods for teff.

Arbuscular mycorrhizal fungi associated with the babassu palm (Attalea speciosa) in the eastern periphery of Amazonia, Brazil

ABSTRACT Babassu, Attalea speciosa (Arecaceae) is a ruderal palm native to Amazonia, which turned dominant in frequently burned lands throughout the ‘arc of deforestation’ and other degraded lands, in extreme cases attaining complete dominance. This study investigated arbuscular mycorrhizal fungi (AMF) as one possible explanation for the outstanding ecological success of this exceptional palm. We explored the relationships between the babassu palm and native arbuscular mycorrhizal fungi and babassu effects on the AMF richness and mycorrhizal inoculum potential (MIP) in the eastern periphery of Amazonia. For this purpose, we sampled topsoil (0-20 cm) at the onset of the rainy season from a 5-year-old secondary forest regrowth (SEC) area with three levels of babassu dominance (sites with 10, 50 and 70% babassu biomass shares), and at three distances (0, 2.5 and 4 m) from isolated babassu patches within a degraded pasture (PAS), both with five replications per treatment. Glomerospore density varied from 100 to 302 per gram of soil, 56% higher in SEC than PAS. We identified a total of 16 AMF species, with dominance of Acaulospora (six species) followed by Glomus (three species). AMF richness increased with babassu dominance in SEC sites, and reduced with distance from babassu patches within the PAS. The colonization rate of babassu roots was higher in SEC than in PAS, whereas MIP was similar in both areas and without treatment differences. Our study points to strong mycorrhizal association of the babassu palm as a potential mechanism for its outstanding ecological success in degraded lands.

Exploring the use of legumes as host plant species in Glomus mosseae sporulation

The production of high quality, large scale, pathogen free and homogenous mycorrhizal inoculums are required for research purposes and soil bio-fertility. In the current study, a pot culture technique was followed to produce healthy quality and mass quantity of Glomus mosseae spores for research purposes. Five legumes plants were selected {(pea (Pisum sativum), broad bean, (Vicia faba) black eyed beans (Vigna unguiculata) soybean (Glycine max), and mung beans (Phaseolus aureus)}. The legumes were grown for two months under controlled conditions after pre-inoculated with healthy G. mosseae spores. The highest number of spores was counted in the mung beans rhizosphere and it was the best host in nodules weight production and root colonization rate. Soybeans produced the lowest spore’s number. It was found that the correlation between root colonization rate and spores number in the soil was positive. The rhizobium nodule weight was related positively with arbuscular mycorrhizal fungi spores manipulations in the soil.

Selection of arbuscular mycorrhizal fungal strains to improve Casuarina equisetifolia L. and Casuarina glauca Sieb. tolerance to salinity

Selection of the best salt-tolerant combination of Casuarina sp. and arbuscular mycorrhizal fungi (AMF) is one of the key criteria for successful setup of saline land rehabilitation program. Land salinization is a serious problem worldwide that mainly leads to soil degradation and reduces crop productivity. These degraded areas could be rehabilitated by planting salt-tolerant species like Casuarina glauca Sieb. and Casuarina equisetifolia L. These are pioneer plants, able to form symbiotic associations with arbuscular mycorrhizal fungi (AMF), ectomycorrhizal fungi (EMF), and nitrogen-fixing bacteria. The aim of this study was to select the highest salt-tolerant combination of Casuarina/AMF that can be used for the rehabilitation of lands degraded by salinity. C. equisetifolia and C. glauca were grown in sandy sterile soil in the greenhouse and inoculated separately with Rhizophagus fasciculatus (Thaxt.) C. Walker & A. Schusler, Rhizophagus aggregatus (N.C. Schenck & G.S. Sm.) C. Walker, and Rhizophagus intraradices (N.C. Schenck & G.S. Sm.) C. Walker & A. Schusler. After confirming the establishment of a symbiosis, the plants were watered with gradually increasing concentrations of saline solution. After harvest, size and biomass of the seedlings, root colonization by AMF, and AMF metabolic activities were evaluated. A larger growth was obtained in the two species when the individuals were inoculated with R. fasciculatus. Root colonization rates did not differ among fungal species, but fungal metabolic activities were higher in mycorrhizal roots of C. glauca plants inoculated with R. fasciculatus. Among the three mycorrhizal fungi, R. fasciculatus was more efficient in association with Casuarinaceae species under salt stress. Our results suggest that selection of appropriate fungal strains is crucial to improve plant performance in saline soils.

Decreased ZnO nanoparticle phytotoxicity to maize by arbuscular mycorrhizal fungus and organic phosphorus.

ZnO nanoparticles (NPs) are applied in a wide variety of applications and frequently accumulate in the environment, thus posing risks to the environment and human health. Arbuscular mycorrhizal (AM) fungi (AMF) associate symbiotically with roots of most higher plants, helping their host plants acquire phosphorus (P). AMF can reduce the toxicity of ZnO NPs, but the benefits of AMF to host plants highly vary with soil available P. We hypothesize that organic P may help AMF to alleviate ZnO NP phytotoxicity. Here, we investigated the effects of inoculation with Funneliformis mosseae on plant growth and Zn accumulation, using maize grown in soil-sand mix substrates spiked with ZnO NPs (0 or 500mgkg-1) under different organic P supply levels (0, 20, or 50mgkg-1). The results showed addition of ZnO NPs inhibited root colonization rate, increased the shoot/root P concentration ratio, and led to significant Zn accumulation in soil and plants. As predicted, AM effects on maize plants all varied with P supply levels, both with or without ZnO NP additions. Organic P interacted synergistically with AMF to promote plant growth and acquisition of P, N, K, Fe, and Cu. AM inoculation reduced the bioavailable Zn released from ZnO NPs and decreased the concentrations and translocation of Zn to maize shoots. In conclusion, ZnO NPs caused excess Zn in soil and plants, posing potential environmental risks. However, our present results first demonstrate that organic P exhibited similar positive effects to AMF and interacted synergistically with AMF to improve plant growth and nutrition, and to decrease Zn accumulation and partitioning in plants, and thus helped diminish the adverse effects induced by ZnO NPs.

Effects of arbuscular mycorrhizal symbiosis on growth, nutrient and metal uptake by maize seedlings (Zea mays L.) grown in soils spiked with Lanthanum and Cadmium

Multiple contaminants can affect plant-microbial remediation processes because of their interactive effects on environmental behaviour, bioavailability and plant growth. Recent studies have suggested that arbuscular mycorrhizal fungi (AMF) can facilitate the revegetation of soils co-contaminated with rare earth elements (REEs) and heavy metals. However, little is known regarding the role of AMF in the interaction of REEs and heavy metals. A pot experiment was conducted to evaluate the effects of Claroideoglomus etunicatum on the biomass, nutrient uptake, metal uptake and translocation of maize grown in soils spiked with Lanthanum (La) and Cadmium (Cd). The results indicated that individual and combined applications of La (100 mg kg−1) and Cd (5 mg kg−1) significantly decreased root colonization rates by 22.0%–35.0%. With AMF inoculation, dual-metal treatment significantly increased maize biomass by 26.2% compared to single-metal treatment. Dual-metal treatment significantly increased N, P and K uptake by 20.1%–76.8% compared to single-metal treatment. Dual-metal treatment significantly decreased shoot La concentration by 52.9% compared to single La treatment, whereas AM symbiosis caused a greater decrease of 87.8%. Dual-metal treatment significantly increased shoot and root Cd concentrations by 65.5% and 58.7% compared to single Cd treatment and the La translocation rate by 142.0% compared to single La treatment, whereas no difference was observed between their corresponding treatments with AMF inoculation. Furthermore, AMF had differential effects on the interaction of La and Cd on metal uptake and translocation under the background concentrations of soil metals. Taken together, these results indicated that AMF significantly affected the interaction between La and Cd, depending on metal types and concentrations in soils. These findings promote a further understanding of the contributions of AMF to the phytoremediation of co-contaminated soil.

Pinewood nematode infection alters root mycoflora ofPinus tabulaeformisCarr

This study investigates pinewood nematode's impacts on root mycoflora of Pinus tabulaeformis. The biomass, colonization rate, community structure and diversity of root-associated fungi were investigated in pinewood nematode-infected and nematode-noninfected P. tabulaeformis. The results indicated that the roots of P. tabulaeformis were colonized highly by root-associated fungi, mainly ectomycorrhizal fungi (ECMF) and dark septate endophytes. Infection of pinewood nematode was associated with a significant (P<0·05) decrease in root colonization rates by ECMF, dark septate endophytes and total hyphae, as well as in fungal biomass in the roots. Illumina MiSeq sequences of tagged amplicons of 18S rDNA region revealed Basidiomycota (65·70%) and Ascomycota (34·14%) as the dominant root-associated fungi in roots of P. tabulaeformis. Among the detected operational taxonomic units (OTUs), ECMF and dark septate endophytes exhibited a higher relative abundance in trees infected by pinewood nematode compared with noninfected ones. The infection of pinewood nematode altered the composition and OTU abundance of root-associated fungi community in P. tabulaeformis roots with a decrease in the biomass, species richness and diversity of root-associated fungi, as well as in the colonization rates and abundance of ECMF and dark septate endophytes. This study is an important contribution for better understanding the interaction between pine wilt disease and root-associated fungi.

Silicon influences growth and mycorrhizal responsiveness in strawberry plants.

Effect of silicon (Si) on the response of strawberry (Fragaria × ananassa var. Parus) plants to arbuscular mycorrhizal fungus (AMF) was studied under growth chamber conditions. Plants were grown in perlite irrigated with nutrient solution without (- Si) or with (+ Si) 3mmolL-1 Si (~ 84mg L-1 Si as Na2SiO3) in the absence (- AMF) or presence (+ AMF) of fungus. Dry matter production, root colonization rate, photosynthesis rate and water relation parameters were all improved by both Si and AMF, and the highest amounts were achieved by + Si + AMF treatment. Mycorrhizal effectiveness increased by Si treatment associated with higher Si concentration in the + AMF plants. Leaf concentrations of total soluble and cell wall-bound phenolics were increased by Si accompanied by the enhanced activity of phenylalanine ammonia lyase, but not polyphenol oxidase. Profile of phenolics compound revealed that gallic acid, caffeic acid, epicatechin, chlorogenic acid, ellagic acid and kaempferol increased by both Si and AMF treatments, while p-coumaric acid decreased. In addition to vegetative growth, both treatments improved fruit yield and its quality parameters. Our results showed that Si and AMF acted in a synergistic manner and improved growth and biochemical parameters in strawberry plants. However, the mechanism for Si-mediated increase of mycorrhizal effectiveness is not known, thereby needing further elucidation.

Intercropping Acacia mangium stimulates AMF colonization and soil phosphatase activity in Eucalyptus grandis

Arbuscular mycorrhizal fungi (AMF) are very important to plant nutrition, mostly in terms of acquisition of P and micronutrients. While Acacia mangium is closely associated with AMF throughout the whole cycle, Eucalyptus grandis presents this symbiosis primarily at the seedling stage. The aim of this study was to evaluate the dynamics of AMF in these two tree species in both pure and mixed plantations during the first 20 months after planting. We evaluated the abundance, richness and diversity of AMF spores, the rate of AMF mycorrhizal root colonization, enzymatic activity and soil and litter C, N and P. There was an increase in AMF root colonization of E. grandis when intercropped with A. mangium as well as an increase in the activity of acid and alkaline phosphatase in the presence of leguminous trees. AMF colonization and phosphatase activities were both involved in improvements in P cycling and P nutrition in soil. In addition, P cycling was favored in the intercropped plantation, which showed negative correlation with litter C/N and C/P ratios and positive correlation with soil acid phosphatase activity and soil N and P concentrations. Intercropping A. mangium and E. grandis maximized AMF root colonization of E. grandis and phosphatase activity in the soil, both of which accelerate P cycling and forest performance.

Examining Arbuscular Mycorrhizal Fungi in Saltmarsh Hay (Spartina patens) and Smooth Cordgrass (Spartina alterniflora) in the Minas Basin, Nova Scotia

Saltmarshes are highly productive ecosystems that provide nursery and refuge habitat for animals, buffer storm-wave effects, and stabilize coastlines. Unfortunately, saltmarshes are in decline due to several cumulative stressors. Beneficial root-associated fungi are known to colonize >80% of land plants, but are understudied in intertidal zones. We examined arbuscular mycorrhizal fungi (AMF) in the roots of 2 dominant saltmarsh cordgrasses, Spartina patens (Saltmarsh Hay) and Spartina alterniflora (Smooth Cordgrass) (Poaceae), in the Minas Basin, NS, Canada. We collected 9 sediment cores at the beginning, middle, and end of the 2016 growing season (May–September) for each plant species (n = 54). We examined AMF root colonization using microscopy and fungal-DNA barcoding. Smooth Cordgrass had an AMF root colonization rate of 9%, while Saltmarsh Hay exhibited a higher AMF root colonization rate of 68%. We identified 1 AMF species, Funneliformis geosporum (Glomeraceae), in both host-plant species. We present the first Spartina spp. (cordgrasses) AMF root-colonization data for northeastern North America north of Connecticut, which may aid saltmarsh restoration efforts in Nova Scotia.

Improvement of Soil Properties, Growth of Cucumber and Protection against Fusarium Wilt by Piriformospora indica and Two Industrial Organic Wastes

The current work was focused on characterizing bagasse ash (BA) and press mud (PM) as soil amendments and to study their effect in combination with the endophytic fungus Piriformospora indica on Fusarium wilt (FW) of cucumber caused by Fusarium oxysporum f. sp. cucumerinum (Fo). Whereas BA and PM improved almost all physico-chemical properties of the soil evaluated, seed treatment with P. indica had no such effect. In shake culture in potato dextrose broth (PDB) medium amended with aqueous extracts of BA and PM, alone or in combination, production mycelial mass of Fo was significantly decreased by PM extract, while production mycelial mass of P. indica was highly improved. The colonization rate of cucumber roots by P. indica as determined by microscopy was highly increased by increasing amounts of BA, PM and BA+PM added to the soil. Seed treatment of cucumber with P. indica before plant cultivation in non-amended soil significantly decreased the disease severity of FW and improved plant growth. When seed treated with P. indica was sown into soil amended with BA, PM or the combination of both, the disease severity was even more reduced than after seed treatment with P. indica alone. In this respect, amendment with PM was more effective than with BA, and the combinations were more effective than the single treatments. Hence, there is a scope to integrate PM and BA as soil amendments in combination with P. indica for eco-friendly FW management, improving soil properties and growth of cucumber plants.

The phytoprotective effects of arbuscular mycorrhizal fungi on Enterolobium contorstisiliquum (Vell.) Morong in soil containing coal-mine tailings

ABSTRACTThe purpose of this study was to evaluate the effects of arbuscular mycorrhizal fungi (AMF) on pacara earpod tree (Enterolobium contorstisiliquum) growth and phytoprotection in soil containing coal-mining waste. A greenhouse experiment was carried out with three inoculation treatment groups (non-inoculated, inoculated with Rhizophagus clarus, and inoculated with Acaulospora colombiana) in two substrates (0 or 30% tailings). After 90 days the seedlings were collected to quantify growth parameters, quality, mycorrhizal root colonization rate, and leaf content of chlorophylls and carotenoids. Macronutrients were quantified in the shoots; Cu, Zn, and Mn levels were measured in the shoots and roots; and glomalin content was measured in the rhizosphere. Colonization by A. colombiana (40%) promoted phytoprotection and better growth in seedlings planted in partial tailing substrate, due to the lower Cu (1.04 mg kg−1) and Zn (13.4 mg kg−1) levels in shoot dry mass and reduced translocation of these elements to the shoots. A. colombiana increased soil glomalin concentrations (2.98 mg kg−1) and the accumulation of nutrients necessary for synthesizing chlorophylls and carotenoids in the leaves. Colonization by R. clarus (81%) produced no phytoprotective effects.

Sand mining disturbances and their effects on the diversity of arbuscular mycorrhizal fungi in a riparian forest of Iran

The major objective of this study was to evaluate the effects of sand mining disturbances on the diversity of arbuscular mycorrhizal fungi (AMF). In addition, the proportional changes in the diversity of AMF to the distances from riverbanks were assessed. For this purpose, the riparian forest of the Maroon River, Iran was divided into three locations with a 200-meter wide zone in between. Thus, the locations studied were named Distance I (riverbank), Distance II (intermediate), and Distance III (farthest from riverbank). In each of these distances, 10 Tamarix arceuthoides and Populus euphratica of each species were randomly selected. At the same time, soil and root samples were collected from the rhizosphere of the tree species studied. Results indicated that totally 13 AMF species were observed in T. arceuthoides and 19 AMF species were recorded in P. euphratica rhizosphere belonging to 6 genera and 6 families. In these AMF species, Glomus segmentatum, G. geosporum, G. rubiforme, G. nanolumen, G. spinuliferum, Claroideoglomus drummondii, Gigaspora gigantea and Acaulospora paulinae appeared only in P. euphratica rhizosphere, while G. multiforum and Claroideoglomus claroideum were observed only in T. arceuthoides rhizosphere. Moreover, Distance II had the least AMF species both in T. arceuthoides and in P. euphratica rhizospheres, and also the least spore density and root colonization rate. Our results are important in that they provide a list of resistant AMF species that could be used in the conservation of biodiversity.

The effect of Glomus intraradices on the physiological properties of Panax ginseng and on rhizospheric microbial diversity

BackgroundGlomus intraradices is a species of arbuscular mycorrhizal fungi that, as an obligate endomycorrhiza, can form mutually beneficial associations with plants. Panax ginseng is a popular traditional Chinese medicine; however, problems associated with ginseng planting, such as pesticide residues, reduce the ginseng quality. MethodsIn this experiment, we studied the effect of inoculating G. intraradices on several physiological properties and microbial communities of ginseng. UV-Visible Spectrum method was used to detect physical properties. Denaturing gradient gel electrophoresis method was used to analyze microbial communities. ResultsThe results indicated that inoculation with G. intraradices can improve the colonization rate of lateral ginseng roots, increase the levels of monomeric and total ginsenosides, and improve root activity as well as polyphenol oxidase and catalase activities. We also studied the bacterial and fungal communities in ginseng rhizospheric soil. In our study, G. intraradices inoculation improved the abundance and Shannon diversity of bacteria, whereas fungi showed a reciprocal effect. Furthermore, we found that G. intraradices inoculation might increase some beneficial bacterial species and decreased pathogenic fungi in rhizospheric soil of ginseng. ConclusionOur results showed that G. intraradices can benefit ginseng planting which may have some instructive and practical significance for planting ginseng in farmland.

Mycorrhizal relationship in lupines: a review

Legume crops are widely cultivated with agronomical and economic significance. Majority of legume species are known to form mycorrhizal symbioses. However, plants in the genus Lupinus are generally considered as nonmycorrhizal. In this review, published researches with regards to mycorrhizal colonization and function in lupines were revisited. Research findings on mycorrhizal colonization (field or laboratory conditions) and functions (promotion in plant growth, nutrient uptake and metabolites) are summarized. These studies show that 35 out of 43 Lupinus species are colonized by mycorrhizal fungi although their root colonization rates are very low (&gt;10%). The symbiotic status between mycorrhizal fungi and Lupinus species depend on lupine species, fungal taxa, and edaphic growth conditions. The functions of mycorrhizas on lupines exhibit more on physiology than the absorption of P. The responses of lupines to mycorrhizal fungi changed depending on mycorrhizal and Lupinus species and especially soil P concentrations. Based on current limited studies, conclusions on the nature of mycorrhizal relation in lupine could be compromised unless further studies with detailed field surveys and well-designed experiments are implemented.

Application of Mycorrhiza and Soil from a Permaculture System Improved Phosphorus Acquisition in Naranjilla.

Naranjilla (Solanum quitoense) is a perennial shrub plant mainly cultivated in Ecuador, Colombia, and Central America where it represents an important cash crop. Current cultivation practices not only cause deforestation and large-scale soil degradation but also make plants highly susceptible to pests and diseases. The use of arbuscular mycorrhizal fungi (AMF) can offer a possibility to overcome these problems. AMF can act beneficially in various ways, for example by improving plant nutrition and growth, water relations, soil structure and stability and protection against biotic and abiotic stresses. In this study, the impact of AMF inoculation on growth and nutrition parameters of naranjilla has been assessed. For inoculation three European reference AMF strains (Rhizoglomus irregulare, Claroideoglomus claroideum, and Cetraspora helvetica) and soils originating from three differently managed naranjilla plantations in Ecuador (conventional, organic, and permaculture) have been used. This allowed for a comparison of the performance of exotic AMF strains (reference strains) versus native consortia contained in the three soils used as inocula. To study fungal communities present in the three soils, trap cultures have been established using naranjilla as host plant. The community structures of AMF and other fungi inhabiting the roots of trap cultured naranjilla were assessed using next generation sequencing (NGS) methods. The growth response experiment has shown that two of the three reference AMF strains, a mixture of the three and soil from a permaculture site led to significantly better acquisition of phosphorus (up to 104%) compared to uninoculated controls. These results suggest that the use of AMF strains and local soils as inoculants represent a valid approach to improve nutrient uptake efficiency of naranjilla and consequently to reduce inputs of mineral fertilizers in the cultivation process. Improved phosphorus acquisition after inoculation with permaculture soil might have been caused by a higher abundance of AMF and the presence of Piriformospora indica as revealed by NGS. A higher frequency of AMF and enhanced root colonization rates in the trap cultures supplemented with permaculture soil highlight the importance of diverse agricultural systems for soil quality and crop production.