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O feijão-caupi ou feijão-macassar [Vigna unguiculata (L.) Walp.] é conhecido por ser excelente fonte de proteínas, carboidratos, vitaminas e minerais, além de fibras dietéticas e baixa quantidade de gordura. Uma das alternativas para a redução do uso de fertilizantes minerais é a utilização de fungos micorrízicos arbusculares inoculados na semeadura das sementes.O objetivo deste trabalho foi avaliar os efeitos do fungo micorrízico arbuscular, Gigaspora margarita, no crescimento e desenvolvimento do feijão-caupi em resposta a doses de fósforo. O experimento, constituído de sete tratamentos (dois sem inoculação e cinco inoculados e com doses de fósforo), foi desenvolvido entre os meses de março e junho de 2021, no Instituto Federal da Paraíba, Campus Cabedelo. O delineamento experimental foi em blocos casualizados e quatro repetições por tratamento. As variáveis analisadas foram altura e diâmetro dos caules, número de lançamentos foliares, matéria seca de parte aérea, raízes e vagens, teores de nutrientes nos grãos e nas folhas, além de análise microscópica da colonização radicular. Constatou-se a contribuição do Gigaspora margarita em promover o crescimento e desenvolvimento do feijão-caupi quando as plantas foram adubadas com 50% da dose de fósforo recomendada, o que pode significar economia em termos de adubação fosfatada para o pequeno agricultor.

ABSTRACT Arbuscular mycorrhizal fungi increase water and nutrient absorption from the soil by plants. However, its benefits to plants vary depending on the inoculated species. This study aimed to determine the influence of different species of mycorrhizal fungi on the development and productivity of grain sorghum cultivars. The experiment was conducted in a greenhouse in a completely randomized design in a 2 x 5 factorial scheme, consisting of two sorghum cultivars (BRS 310 and BRS 330) and five treatments (control without inoculation and four species of arbuscular mycorrhizal fungi: Gigaspora margarita, Glomus formosanum, Acaulospora scrobiculata, and Scutellospora pellucida), with four replications. Plant height, stem diameter, leaf area, length, volume, specific surface area, root diameter, shoot dry mass, root dry mass, thousand-grain weight, grain productivity, colonization, dependence, and mycorrhizal efficiency were evaluated. The results showed that inoculation with the species S. pellucida induced higher root and shoot development of plants of the cultivar BRS 310, as well as higher productivity of sorghum grains. The cultivar BRS 330 showed higher root development when inoculated with the species G. formosanum and a higher shoot development when inoculated with the species A. scrobiculata. Mycorrhizal dependence for grain productivity was low and varied with the inoculated species of mycorrhizal fungi. The mycorrhizal efficiency for shoot dry mass was higher with the inoculation of A. scrobiculata and S. pellucida in the cultivar BRS 310 and A. scrobiculata and G. margarita in the cultivar BRS 330.

Abstract The symbiosis between arbuscular mycorrhizal fungi (AMF) and fruit tree plants is a sustainable strategy for producing seedlings. However, information for Dipteryx alata Vogel., a native species, is still scarce. Thus, this study aimed to identify the most promising AMF inoculum for producing D. alata seedlings and their effects on growth. Seedlings were inoculated with Clareoideoglomus etunicatum, Gigaspora albida, Gigaspora margarita, a mixture of these three species, and an uninoculated control. Height, diameter, and chlorophyll index were evaluated at 30, 60, 90, 120, 150, and 180 days after seedling transplanting, while biomass production, quality index, dependence, and mycorrhizal efficiency were evaluated at 180 days. Greater diameter and height values were observed for D. alata seedlings at 180 days and inoculated with G. albida, G. margarita, and the mixture. AMF of the genus Gigaspora positively contributed to biomass production and seedling quality. D. alata seedlings show high mycorrhizal dependence on G. albida and G. margarita inoculum, which had good mycorrhizal efficiency. AMF, especially those of the genus Gigaspora, favor the production of high-quality D. alata seedlings.

The corn crop is of great importance for the Cerrado region, and phosphorus absorption is a limiting factor for its development. The symbiotic relationship of arbuscular mycorrhizal fungi allows greater absorption of water and nutrients by the hosts, however, factors such as the availability of nutrients can affect this relationship. The aim was to evaluate the effect of arbuscular mycorrhizal fungi associated with different doses of phosphorus on corn. An experiment was carried out in a 3x5 factorial scheme, composed of arbuscular mycorrhizal fungi species (Acaulospora scrobiculata and Gigaspora margarita) and a control treatment, with the addition of phosphate fertilizer MAP at doses of 0, 25, 50, 100, and 200 mg.dm-3. At 45 days after sowing, the biometric characteristics of the plant, biomass, leaf P, and root colonization were evaluated. There was interaction between the analyzed variables, with the control being inferior to the inoculated treatments, and the species A. scrobiculata was more responsive at higher doses of phosphorus, while G. margarita provided better results at low doses of phosphorus. It is concluded that the plants inoculated with the AMF species present better development and that the dosages of phosphate fertilizer affect the species differently. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi allocate mineral nutrients to their host plants, and the hosts supply carbohydrates and lipids to the fungal symbionts in return. The morphotypes of intraradical hyphae are primarily determined on the plant side into Arum- and Paris-type AMs. As an exception, Solanum lycopersicum (tomato) forms both types of AMs depending on the fungal species. Previously, we have shown the existence of diverse regulatory mechanisms in Arum- and Paris-type AM symbioses in response to gibberellin (GA) among different host species. However, due to the design of the study, it remained possible that the use of different plant species influenced the results. Here, we used tomato plants to compare the transcriptional responses during Arum- and Paris-type AM symbioses in a single plant species. The tomato plants inoculated with Rhizophagus irregularis or Gigaspora margarita exhibited Arum- and Paris-type AMs, respectively, and demonstrated similar colonization rates and shoot biomass. Comparative transcriptomics showed shared expression patterns of AM-related genes in tomato roots upon each fungal infection. On the contrary, the defense response and GA biosynthetic process was transcriptionally upregulated during Paris-type AM symbiosis. Thus, both shared and different transcriptional reprogramming function in establishing Arum- and Paris-type AM symbioses in tomato plants. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs, and the difficulty of growing them in asymbiotic or monoxenic (AMF + root) conditions limits research and their large-scale production as biofertilizer. We hypothesized that a combination of flavanols and strigolactones can mimic complex root signaling during the presymbiotic stages of AMF. We evaluated the germination, mycelial growth, branching, and auxiliary cell clusters formation by Gigaspora margarita during the presymbiotic stage in the presence (or absence) of transformed Cichorium intybus roots in basal culture medium enriched with glucose, a flavonol (quercetin or biochanin A) and a strigolactone analogue (1-Methyl-2-oxindole or indole propionic acid). With quercetin (5 µM), methyl oxindole (2.5 nM), and glucose (8.2 g/L) in the absence of roots, the presymbiotic mycelium of G. margarita grew without cytoplasmic retraction and produced auxiliary cells over 71 days similar to presymbiotic mycelium in the presence of roots but without glucose, strigolactones, and flavonols. Our results indicate that glucose and a specific combination of certain concentrations of a flavonol and a strigolactone might be used in asymbiotic or monoxenic liquid or semisolid cultures to stimulate AMF inoculant bioprocesses. [ABSTRACT FROM AUTHOR]

Piliostima reticulatum and Guiera senegalensis shrubs constitute "islands of soil fertility" in the rhizosphere, with better availability of water and more intense biological activity in the Sudano-Sahelian agro-ecosystems. There is, however, paucity of information on diversity of arbuscular mycorrhizal fungi (AMF) fungi, which have a wide ecological range of associations with a variety of vegetation. The purpose of this study was to identify the types of AMF in the rhizospheres of P. reticulatum and G. senegalensis shrubs in Senegal. Soil samples were collected from around the shrubs in Keur Matar Arame and Keur Ndary Ndiaye in 2019 after a rainy season. Arbuscular mycorrhizae fungi spores were isolated by the wet sieving method and identified based on their morphological characteristics (shape, size, colour, attached hyphae, and spore ornamentation). Four types of AMF were identified, namely Glomus aggregatum, Sclerocystis rubiformis, Gigaspora margarita and Scutellospora gregaria. In addition, the density of spores was more abundant in the soil outside the shrub canopy compare to the soil beneath the shrub. [ABSTRACT FROM AUTHOR]

Penelitian ini bertujuan untuk menentukan kombinasi antara jenis inokulum Vesikular Arbuskular Mikoriza (VAM), kandungan NPK, dan umur tanaman yang paling efektif dalam produksi inokulum. Tanaman inang menggunakan Sorghum bicolor yang merupakan anggota dari famili Poaceae yang memiliki sistem perakaran yang luas, jumlah akar banyak, dan tumbuh dengan cepat sehingga berpotensi sebagai inang VAM yang kompatibel. Penelitian ini menggunakan analisis Rancangan Acak Lengkap (RAL) dengan faktorial 2x2x2 meliputi jenis mikoriza yang digunakan yaitu Glomus aggregatum (G) dan campuran Glomus aggregatum dan Gigaspora margarita (C). Konsentrasi NPK, yaitu NPK grower 15-9-20 (P9) dan Growmore 20-20-20 (P20). Umur tanaman 6 minggu dan 9 minggu. Parameter pertumbuhan yang diukur meliputi tinggi tanaman, berat kering batang dan akar, persen kolonisasi dan jumlah spora VAM. Berdasarkan penelitian didapatkan hasil, tanaman dengan inokulum campuran VAM dengan P20 menghasilkan tinggi tanaman dan berat kering batang dan akar tertinggi. Inokulum campuran mempunyai persen kolonisasi dengan nilai yang paling tinggi, sedangkan inokulum tunggal (Glomus aggregatum) dengan P rendah menghasilkan produksi spora paling tinggi. Inokulum campuran VAM dan P9 lebih baik dalam produksi inokulum, baik berupa akar terkolonisasi maupun spora.

RNA interference (RNAi) is a key regulatory pathway of gene expression in almost all eukaryotes. This mechanism relies on short non-coding RNA molecules (sRNAs) to recognize in a sequence-specific manner DNA or RNA targets leading to transcriptional or post-transcriptional gene silencing. To date, the fundamental role of sRNAs in the regulation of development, stress responses, defense against viruses and mobile elements, and cross-kingdom interactions has been extensively studied in a number of biological systems. However, the knowledge of the “RNAi world” in arbuscular mycorrhizal fungi (AMF) is still limited. AMF are obligate mutualistic endosymbionts of plants, able to provide several benefits to their partners, from improved mineral nutrition to stress tolerance. Here we described the RNAi-related genes of the AMF Gigaspora margarita and characterized, through sRNA sequencing, its complex small RNAome, considering the possible genetic sources and targets of the sRNAs. G. margarita indeed is a mosaic of different genomes since it hosts endobacteria, RNA viruses, and non-integrated DNA fragments corresponding to mitovirus sequences. Our findings show that G. margarita is equipped with a complete set of RNAi-related genes characterized by the expansion of the Argonaute-like (AGO-like) gene family that seems a common trait of AMF. With regards to sRNAs, we detected populations of sRNA reads mapping to nuclear, mitochondrial, and viral genomes that share similar features (25-nt long and 5′-end uracil read enrichments), and that clearly differ from sRNAs of endobacterial origin. Furthermore, the annotation of nuclear loci producing sRNAs suggests the occurrence of different sRNA-generating processes. In silico analyses indicate that the most abundant G. margarita sRNAs, including those of viral origin, could target transcripts in the host plant, through a hypothetical cross-kingdom RNAi.

More than 70% of vascular plant species live in symbiosis with arbuscular mycorrhizal (AM) fungi. In addition to other effects this symbiosis is known for its significance for plant nutrition including iron. Fungal iron mobilization from soil is commonly dependent on siderophores. This study reports on a search for such iron-chelators in root tissue of Tagetes patula nana var. plena colonized by Gigaspora margarita. The AM colonized plants and uninoculated controls were grown under strictly axenic conditions. HPLC analyses of aqueous extracts from plant roots have provided clear evidence for the presence of a rhizoferrin type siderophore, named glomuferrin, in root tissue of mycorrhizal seedlings. Results from HPLC analytical work are seconded by molecular biological data: A BLASTp search revealed that the AM fungal species Gigaspora rosea, Rhizophagus irregularis (formerly Glomus intraradices), Glomus cerebriformis and Diversispora epigea encode a non-ribosomal peptide synthetase (NRPS)-independent siderophore synthase (NIS), which is homologous to the rhizoferrin synthetase of Rhizopus delemar. Thus this study indicates that the biosynthesis of rhizoferrin type siderophores such as glomuferrin (= bis-imidorhizoferrin) may be widespread in the AM symbiosis. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) is a key regulatory pathway of gene expression in almost all eukaryotes. This mechanism relies on short non-coding RNA molecules (sRNAs) to recognize in a sequence-specific manner DNA or RNA targets leading to transcriptional or post-transcriptional gene silencing. To date, the fundamental role of sRNAs in the regulation of development, stress responses, defense against viruses and mobile elements, and cross-kingdom interactions has been extensively studied in a number of biological systems. However, the knowledge of the "RNAi world" in arbuscular mycorrhizal fungi (AMF) is still limited. AMF are obligate mutualistic endosymbionts of plants, able to provide several benefits to their partners, from improved mineral nutrition to stress tolerance. Here we described the RNAi-related genes of the AMF Gigaspora margarita and characterized, through sRNA sequencing, its complex small RNAome, considering the possible genetic sources and targets of the sRNAs. G. margarita indeed is a mosaic of different genomes since it hosts endobacteria, RNA viruses, and non-integrated DNA fragments corresponding to mitovirus sequences. Our findings show that G. margarita is equipped with a complete set of RNAi-related genes characterized by the expansion of the Argonaute-like (AGO-like) gene family that seems a common trait of AMF. With regards to sRNAs, we detected populations of sRNA reads mapping to nuclear, mitochondrial, and viral genomes that share similar features (25-nt long and 5′-end uracil read enrichments), and that clearly differ from sRNAs of endobacterial origin. Furthermore, the annotation of nuclear loci producing sRNAs suggests the occurrence of different sRNA-generating processes. In silico analyses indicate that the most abundant G. margarita sRNAs, including those of viral origin, could target transcripts in the host plant, through a hypothetical cross-kingdom RNAi. [ABSTRACT FROM AUTHOR]

Using a microarray approach, 29 putative nutrient-transporter genes were identified as up-/down-regulated transcripts in the model legume Lotus japonicus during the colonization by the arbuscular mycorrizal fungus (AMF) Gigaspora margarita. Among them, transcripts for phosphate, potassium, sulfate, ammonium, nitrate, and other N-transporters were detected, and suggested to be involved in macronutrient uptake by the plant. Based on a bioinformatic analysis, the mycorrhiza-specific phosphate transporter LjPT4 was identified, offering a new tool as a functional marker for future mycorrhiza research on the model plant L. japonicus.Since recent data on AMF physiology are demonstrating that AMF have the capacities to transfer nitrogen, and not only phosphate, from the soil to their host plants, particular attention has been given to a sequence coding for an ammonium transporter (LjAMT2;2). Our results show that the LjAMT2;2 protein is a functional ammonium transporter. Its dependency on an acidic pH and the localization of its expression to arbusculated cells suggest that LjAMT2;2 plays a role in the acquisition of ammonium from the interfacial apoplast during the inorganic N-transfer from the fungus to the host plant.Ten putative amino acid and peptide transporters were identified with the array: their analysis will help to answer the question whether an alternative to the inorganic N-transfer exists in the AM symbiosis. Also transporters for other nutrients (e.g. NO3-, K+ and SO42-) which have been identified, but have not so far been characterized, will represent interesting targets for future studies on nutrient exchange between the two symbionts.

Summary: The intracellular accommodation of arbuscular mycorrhizal (AM) fungi is a paradigmatic feature of this plant symbiosis that depends on the activation of a dedicated signaling pathway and the extensive reprogramming of host cells, including striking changes in nuclear size and transcriptional activity.By combining targeted sampling of early root colonization sites, detailed confocal imaging, flow cytometry and gene expression analyses, we demonstrate that local, recursive events of endoreduplication are triggered in the Medicago truncatula root cortex during AM colonization.AM colonization induces an increase in ploidy levels and the activation of endocycle specific markers. This response anticipates the progression of fungal colonization and is limited to arbusculated and neighboring cells in the cortical tissue. Furthermore, endoreduplication is not induced in M. truncatula mutants for symbiotic signaling pathway genes.On this basis, we propose endoreduplication as part of the host cell prepenetration responses that anticipate AM fungal accommodation in the root cortex. [ABSTRACT FROM AUTHOR]

Land area planted with genetically modified (GM) crops has grown rapidly, and Brazil has the second largest area with those plants. There is, however, limited information on the possible effects of that technology on non-target organisms, especially root symbionts, such as arbuscular mycorrhizal fungi (AMF). We evaluated AMF symbiosis development in five maize genotypes: one landrace, two conventional hybrids (DKB 240 and Formula), and two GM hybrids (DKB 240-VT Pro and Formula TL). We evaluated symbiosis response in two separate experiments: one in autumn and the other in summer. Plants were inoculated with Rhizophagus clarus (Rc) and Gigaspora margarita (Gm) and compared to plants without inoculation. We evaluated root colonization, spore number, and plant biomass and phosphorous accumulation 30 and 60 days after inoculation. There were no consistent effects of GM crops, but AMF species and maize genotype affected symbiosis development. Formula genotype (isoline and GM) had a negative response to inoculation, with a decrease of around 30% in biomass and P concentration in Rc-inoculated plants. The maize landrace had a positive response, with increases of 17% and 14% in the same variables. DKB genotype (isoline and GM) showed negative, positive, and neutral effects. The results show that plant genetic identity is a determinant factor in symbiosis performance, suggesting that plants selected in low P availability can make better use of mycorrhizal symbiosis. Given the role that AMF play in different ecosystem processes, use of landrace maize may contribute to agrobiodiversity conservation. [ABSTRACT FROM AUTHOR]

Abstract Root exudates from Lotus japonicus were found to contain at least three different hyphal branching-inducing compounds for the arbuscular mycorrhizal (AM) fungus Gigaspora margarita , one of which had been previously identified as (+)-5-deoxystrigol (5DS), a canonical strigolactone (SL). One of the two remaining unknown hyphal branching inducers was purified and named lotuslactone. Its structure was determined as methyl (E)-2-(3-acetoxy-2-hydroxy-7-methyl-1-oxo-1,2,3,4,5,6-hexahydroazulen-2-yl)-3-(((R)-4-methyl-5-oxo-2,5-dihydrofuran-2-yl)oxy)acrylate, by 1D and 2D NMR spectroscopy, and HR-ESI- and EI-MS. Although lotuslactone, a non-canonical SL, contains the AB-ring and the enol ether-bridged D-ring, it lacks the C-ring and has a seven-membered cycloheptadiene in the A-ring part as in medicaol, a major SL of Medicago truncatula. Lotuslactone was much less active than 5DS, but showed comparable activity to methyl carlactonoate (MeCLA) in inducing hyphal branching of G. margarita. Other natural non-canonical SLs including avenaol, heliolactone, and zealactone (methyl zealactonoate) were also found to be moderate to weak inducers of hyphal branching in the AM fungus. Lotuslactone strongly elicited seed germination in Phelipanche ramosa and Orobanche minor , but Striga hermonthica seeds were 100-fold less sensitive to this stimulant. Graphical abstract The model legume Lotus japonicus was shown to produce both a canonical and a non-canonical strigolactones as rhizosphere signals. Image 1 Highlights • A novel strigolactone, named lotuslactone, was isolated from Lotus japonicus. • Lotuslactone is a non-canonical strigolactone. • Lotuslactone is a moderate inducer of hyphal branching in Gigaspora margarita. • Lotuslactone is a strong inducer of seed germination in root parasitic plants. [ABSTRACT FROM AUTHOR]

Salinity stress alleviation through arbuscular mycorrhizal fungi (AMF) application and sodium (Na) localization in strawberry plants were investigated. A greenhouse experiment in a completely randomized design with three replications revealed AMF (Gigaspora margarita) association alleviated salinity stress (200 mM NaCl). AMF inoculated plants had greater dry weight, maintained chlorophyll content, and decreased leaves browning compared to the control under salinity stress. The Na+ concentration and Na+/K+ ratio were found lower in the following organs, young and old leaflets and petioles, main roots and lateral roots of mycorrhizal plants than the control. The scanning electron microscope and energy dispersive x-ray spectroscopy (SEM-EDX) analysis of Na in old petiole and main root tissues revealed, excess Na localized in the vascular bundle margin of old petioles and main roots of both the control and mycorrhizal plants. So, suppression of Na absorption through roots might be the mechanism of salt stress alleviation in mycorrhizal plants than to the control Na localization. The higher cellulose and lignin contents in the cell wall of mycorrhizal roots act as the apoplastic barrier which might be suppressing Na influx. [ABSTRACT FROM AUTHOR]

Abstract Control of stem rust disease of wheat was investigated using different combinations of Trichoderma spp. and arbuscular mycorrhizal (AM) fungi. Impact of the application of T. harzianum HL1 and T. viride HL5, singly or in combination, on the uredospores germination of Puccinia graminis Pers. f. sp. tritici was assessed in vitro. The combined spore suspension of both isolates showed the superiority over the others in this regard. Observations of the scanning electron microscopy confirmed this result. Using a GC-MS system, the chemical constitution of the culture filtrates of T. harzianum HL1 and T. viride HL5 was identified. Under the greenhouse conditions, application of AM fungi and Trichoderma spp. significantly reduced the disease measures, induced the peroxidase and polyphenol oxidase enzymes, increased the total phenol content and improved the tested growth and yield parameters. Based on their efficiency and eco-safety, we can recommend the use of this combination in controlling stem rust disease of wheat. Highlights • Stem rust, caused by Puccinia graminis Pers. f. sp. tritici , is one of the most destructive wheat diseases. • Control of stem rust of wheat was investigated using different combinations of Trichoderma spp. and AM fungi. • Impact of the application of T. harzianum and T. viride on the uredospores germination of Puccinia graminis Pers. f. sp. tritici was assessed in vitro. • Application of the bioagents in the greenhouse reduced the disease measures and improved the growth and yield parameters. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi are beneficial symbiotic soil microorganisms and AM technology can find its potential application in the nursery of horticultural industry. When AM fungi have been successfully applied to many wood fruit tree species, little information is available in litchi (Litchi chinensis Sonn.). In this study, the seedlings of two litchi genotypes (‘Baila’ and ‘Heiye’) were inoculated with two AM fungal species (Rhizophagus irregularis and Gigaspora margarita) in the nursery conditions, and the growth and photosynthetic responses of seedlings to AM fungal inoculation were investigated. Results indicated that AM fungi significantly promoted the plant growth of ‘Heiye’ seedlings in terms of biomass, plant height, stem diameter and leaf number, while they slightly decreased these parameters of ‘Baila’. The inoculation effect can be explained by the changes in photosynthetic characteristics induced by AM fungi, because AM fungi increased Amax, Aqe, LSP and decreased LCP of ‘Heiye’ but did not affected those of ‘Baila’. Pn was not affected by AM fungi, however, regression analysis indicated a weaker relationship between biomass and Pn than those between biomass and Amax, LSP or LCP. Our results strongly suggest that AM fungi can differentially affect the seedling growth of litchi genotypes mainly via their effects on photosynthetic characteristics, and that precautions should be taken to select appropriate genotypes as rootstock if AM technology is applied in litchi nursery. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the effects of Arbuscular Mycorrhizal Fungus (AMF) applications on resistance levels of some selected from Van Lake Basin local melon genotypes that were predetermined resistant situations against to the Fom 1 race of Fusarium oxysporum f.sp. melonis. In study carried out at Selçuk University, Agricultural Faculty Experimental greenhouses and laboratories, 65 MUR 01, 65 ERD 06, 65 EDR 03, 13 TAT 01, 65MER 06 and 65 EDR 02 melon genotypes were used as plant material; Glomus intraradices (G. intraradices) and Gigaspora margarita (G. margarita) were used as mycorrhizal fungi. In experiment, the ratios of 1:2:2 sand, garden soil and farmyard manure were used as growth media. To protect the diseases associated from soils and naturally presence of mycorrhizal problems, growth media was irrigated with distilled water. The each plots had the 15 pots with a capacity of 250 ml and there was only one plant in each pot. The experiment was ended after the 40 days from seed sowing. The five plants were taken from each plot for fusarium test and they were put on 30 days observation in laboratory. In the control plots, from various sensitive genotypes, 65 MUR 01, 65 EDR 03, 13 TAT 01 and 65 MER 06 numbered genotypes never became ill in the G. intraradices application. Moreover, 65 MUR 01, 65 ERD 06 and 13 TAT 01 numbered genotypes never became ill in the G. margarita applications. It was indicated G. intraradices mycorrhiza species had generallythe best effect in increasing level of tolerant to Fom 1. [ABSTRACT FROM AUTHOR]

Mycorrhizal association promotes better survival and nutrition of colonized seedling on field, and consequently, increasing of productivity. However, the weed management can interfere on this association, due to incorrect use of glyphosate. This work has assessed the effects of glyphosate drift on the growth and nutrition of arabica coffee plants (Catuaí Vermelho - IAC 99) colonized with arbuscular mycorrhizal fungi (AMF). The experiment was conducted in 2 x 5 factorial scheme, and included inoculated and non-inoculated plants, and five glyphosate subdoses (0.0, 57.6, 115.2, 230.4, and 460.8 g ha-1 of glyphosate), in randomized blocks with five replication. The inoculation was carried during the greenhouse phase of seedlings production with a mixture of Rhizophagus clarus and Gigaspora margarita, and after to transplanting, when the plants had seven pairs of leaves, glyphosate subdoses were applied. The product caused intoxication in up to 60% of non-inoculated and 45% on inoculated plants, when the highest dose of 460.8 g a.e. ha-1 was applied. A negative effect was noted on the growth and phosphorus content of coffee plants, this effect increased depending on glyphosate subdose, but regardless of inoculation. Glyphosate drift reduces the growth and nutrition of plants colonized by species of AMF and native fungi, negatively affecting root colonization of plants treated.

An Experiment was carried out for the management of root - knot nematode, Meloidogyne incognita (Kofoid and White) on mungbean (Vigna radiate L.) with the help of AM fungi. Significant reduction in nematode population and development of mung plant was observed when mung plants were treated with different AM fungi. Four AM fungi were used in the treatment viz. Glomus mosseae, Glomus fasciculatum, Gigaspora gigantea and Gigaspora margarita. These fungi were used in 10gm dose. Remarkable reduction in gall formation and disease severity, increased root, shoot weight were observed in AM treated mung plants. The present investigation indicates that the AM fungi specially Glomus fasciculatum has a great potential against M. incognita. [ABSTRACT FROM AUTHOR]

Conduziu-se um experimento em casa de vegetação para avaliar o crescimento de mudas de mamoeiro inoculadas com fungos micorrízicos arbusculares (FMAs) e com bactérias diazotróficas, na ausência e presença de fósforo. O delineamento experimental foi o de blocos casualizados, em arranjo fatorial 4 x 3 x 2, sendo os tratamentos compostos por: espécies de fungos micorrízicos arbusculares Glomus clarum, Gigaspora margarita, o inóculo misto Glomus clarum + Gigaspora margarita e o controle sem FMAs; as bactérias diazotróficas Stenotrophomonas maltophilia e Azospirillum sp. e o controle sem bactéria diazotrófica; duas doses de fósforo no solo, 0 e 25 mg dm-3, todos com quatro repetições. Aos 105 dias após a semeadura, as plantas foram coletadas e avaliadas quanto à altura, área foliar total, diâmetro do caule, matéria seca da parte aérea, da raiz e matéria seca total, porcentagem de colonização micorrízica e contagem de bactérias diazotróficas nas raízes. As inoculações com os FMAs proporcionam aumentos significativos no crescimento das mudas de mamoeiro, mesmo em condições de baixa disponibilidade de fósforo, independentemente da presença de bactéria diazotrófica. O fungo G. margarita e o inóculo misto G. margarita + G. clarum destacam-se como os mais promissores para a cultura do mamoeiro. A inoculação com bactérias diazotróficas, na ausência ou na presença de FMAs, não propiciou efeito estimulatório ou supressivo no crescimento das mudas de mamoeiro.

En un invernadero del Centro Internacional de Agricultura Tropical, CIAT, Cali (Colombia) se evaluó la aplicación de cinco inóculos de hongos micorrícico arbusculares, HMA: Kuklospora colombiana, Gigaspora margarita, Glomus manihotis y la mezcla de estos con y sin esterilización, en sustrato sin desinfectar (SD) y desinfectado (D) sobre variables de rendimiento (biomasa aérea y radical, longitud radical), colonización por HMA y concentración foliar de nutrientes en la gramínea Melinis minutiflora Beauv., con el objetivo de seleccionar los inóculos más eficientes. Se utilizaron como unidades experimentales materos de 13.5 x 16.0 x 14.0 cm. El sustrato empleado fue suelo procedente de un Inceptisol con baja disponibilidad de nutrientes, tamizado y mezclado con arena. Los inóculos de Gi. margarita y Gl. manihotis presentaron los mejores resultados en la acumulación de biomasa aérea y radical, longitud radical, porcentaje de colonización micorrícica y concentración de elementos. Kuklospora colombiana presentó efectos inhibitorios sobre las variables evaluadas. La condición del sustrato SD favoreció la acumulación de biomasa aérea y radical y la concentración de fósforo (P) en la biomasa aérea, además, estimuló la longitud radical de M. minutiflora. La concentración de N, K, Ca y Mg en la biomasa aérea fue mayor en el sustrato D. Los resultados muestran que Mellinis minutiflora con inoculación HMA es promisoria para la recuperación de suelos degradados.

Phosphate rock fertilizer has slow solubility; therefore, it is suitable and more effective to be applied on annual crop plantation. To increase the solubility and the effectiveness of phosphate rock application, inoculation of the Arbuscular Mycorrhyzal Fungi (AMF) is required. Experiments were conducted at the Cikabayan Farm, Bogor Agriculture Institute, West Java. The objective was to study the effectiveness of AMF inoculation in increasing the potency of Papuan Crandallite Phosphate Rock to the growth of cocoa seedlings. A factorial experiment was set up in a complete randomized design. The first factor was AMF inoculation, consisting of none AMF, Manokwari indigenous AMF and Mycofer AMF, and the second factor was five dosages of the Papuan Crandallite Phosphate Rock (PCPR), consisting of 0, 0.5, 1.0, 1.5 and 2.0 g P2O5 per seedling. The dosage of 2.0 g P2O5 SP-36 per seedling was used as a comparison. Cocoa seeds of F-1 Upper Amazon Hybrid (UAH) were collected from the Coffee and Cacao Research Center, Jember, East Java. The seedlings were grown in polybags of 20 cm x 30 cm size, with ultisol acid soil obtained from Jasinga (West Java) as the growing medium under 60% of shading net for four months. The media contained 17.03 cmol kg-1 of exchangeable Al. The results showed that increasing the dosages of PCPR at the AMF inoculated seedlings resulted to the linear increase of shoot dry weight and P uptake by 50.14% and 64.88%, respectively; and this was lower than the inoculation of Manokwari indigenous AMF which increased shoot dry-weight by 66.30% and P uptake by 65.45%. Whereas the shoot dry-weight and P uptake of the non-mycorrhizal seedlings increased by 73.56% and 121.94%, respectively. Mycofer inoculants were found to be much more effective in increasing the shoot dry-weight by 127.55% and P uptake by 45.16% than that of the Manokwari indigenous AMF, which increased by 95.97% and 21.29% in shoot dry-weight and P uptake, respectively at the PCPR dosage of 2.0 g P2O5 per seedling as compared to the non-inoculated seedlings.

O objetivo neste trabalho foi de avaliar o efeito da inoculação de fungos micorrízicos arbusculares no crescimento de mudas de peroba rosa (Aspidosperma polyneuron). O experimento foi conduzido em delineamento experimental, inteiramente casualizado, em casa de vegetação com seis repetições. Utilizou-se mistura de solo e areia (3:1), desinfestado como substrato, com os seguintes tratamentos de inoculação: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata e uma mistura de fungos micorrízicos arbusculares (FMA). Após 120 dias, observou-se que a colonização micorrízica radicular foi de 28,3% a 48,4% para a mistura de FMA e para G. margarita, respectivamente. As plantas inoculadas com G. margarita e G. clarum apresentaram maior crescimento, indicando o potencial da inoculação desses fungos na produção de mudas.The aim of this study was to examine the effects of arbuscular mycorrhizal fungi (AMF) inoculation on Aspidosperma polyneuron seedlings growth. The experiment was conducted under greenhouse conditions in a randomized design using a disinfected mixture of soil + sand (3:1) with the following treatments: Gigaspora margarita, Glomus clarum, Scutellospora heterogama, Acaulospora scrobiculata, a mixture of arbuscular mycorrhizae fungi (AMF) and a non-inoculated control with six replicates. After 120 days of seed germination, it was observed that root colonization was from 28.3% to 48.4% for mixture of AMF and G. margarita, respectively. The plants inoculated with G. margarita or G. clarum showed higher growth than other treatments, which evidence the potential of AMF inoculation in seedlings production.

The objective of this study was to evaluate the mycorrhizal dependency of mangaba tree (Hancornia speciosa) plantlets, under increasing levels of phosphorus fertilization. The experimental design was completely randomized in a 4×5 factorial arrangement with three mycorrhizal fungi inocula - Gigaspora margarita, Glomus etunicatum, or a pool of native mycorrhizal fungi (Acaulospora longula, Glomus clarum, Gigaspora albida, Paraglomus sp.) -, and a nonmycorrhizal control, in combination with five levels of phosphorus applied to the substrate: 0, 25, 50, 75, and 100 mg kg-1. After 180 days of growth, plantlets with inoculation of native mycorrhizal pool produced more shoot and root dry biomass and had higher shoot phosphorus content and accumulation. The noninoculated control showed the lowest values, independently of the phosphorus level. The highest relative mycorrhizal dependency occurred with the inoculation of native mycorrhizal fungi. Plants with mycorrhizal fungi did not respond to phosphorus addition above 50 mg kg-1. Mangaba tree is highly dependent on mycorrhiza, but the degree of dependency varies according to phosphorus levels and fungal inocula. In general, mangaba tree is more responsive to mycorrhizal fungi inoculation than to phosphorus addition.O objetivo deste trabalho foi avaliar a dependência micorrízica de mudas de mangaba (Hancornia speciosa), em doses crescentes de fósforo. O delineamento experimental foi inteiramente casualizado, em arranjo fatorial 4´5 com três inóculos de fungos micorrízicos - Gigaspora margarita, Glomus etunicatum, ou uma mistura de espécies de fungos micorrízicos nativos (Acaulospora longula, Glomus clarum, Gigaspora albida e Paraglomus sp.) -, e um controle não micorrízico, combinados a cinco doses de fósforo no substrato: 0, 25, 50, 75 e 100 mg kg-1. Após 180 dias, as mudas com inoculação dos fungos micorrízicos nativos produziram mais biomassa seca de parte aérea e raízes e apresentaram maior concentração e acúmulo de fósforo na parte aérea. O controle sem inóculo apresentou os menores valores, independentemente da dose de fósforo. A maior dependência micorrízica relativa ocorreu com a inoculação de fungos micorrízicos nativos. Plantas com inoculação micorrízica não responderam à adição de fósforo, em doses acima de 50 mg kg-1. A mangabeira é altamente dependente de micorrizas, mas o grau de dependência varia de acordo com os níveis de fósforo e com os inóculos fúngicos. Em geral, a mangabeira é mais responsiva à inoculação com fungos micorrízicos do que à adição de fósforo.

Indolacetic acid (IAA) production was evaluated under in vitro conditions by five P-solubilizing fungi (PSF), identified as Aspergillus sp. and four P-solubilizing bacteria (PSB) of the Enterobacteriaceae family. The bacteria and fungus isolates were incubated in a liquid medium at 28ºC for two and four days, respectively. Moreover, two PSB isolates of the Enterobacteriaceae family (PSB 8 and PSB 56) were evaluated in relation to their abilityto stimulate or inhibit spore germination and hyphal growth of two arbuscular mycorrhizal fungi (AMF) species under in vitro conditions. Two assays were carried out in Petri dishes with agar (0.8%), the first using the AMF Gigaspora margarita and the second with the AMFScutellospora sp. The treatments were: inoculation of PSB 8; PSB 56 and uninoculated control. P-solubilizing isolates produced different amounts of IAA and most PSF isolates produced higher IAA than PSB. From the 18th day of incubation of Scutellospora sp., a significant increase in hyphal growth in the treatment inoculated with PSB 8 was observed. In contrast, PSB 56 inhibited the hyphal growth of Gigaspora margarita from the 24th day of incubation.Avaliou-se o potencial de produção de ácido indol acético (AIA) in vitro por cinco isolados de fungo solubilizador de fosfato (FSF) do gênero Aspergillus sp. e quatro isolados de bactéria solubilizadora de fosfato (BSF) da família Enterobacteriaceae. Os isolados de bactéria e fungo foram incubados em meio líquido a 28ºC, por dois e quatro dias, respectivamente. Além disso, dois isolados de BSF da família Enterobacteriaceae (BSF 8 e BSF 56) foram avaliados quanto à capacidade de estimular ou inibir a germinação de esporos e odesenvolvimento micelial de duas espécies de fungos micorrízicos arbusculares (FMAs) in vitro. Foram instalados dois ensaios em placas de Petri, contendo agar-água (0,8%); um, utilizando o FMA Gigaspora margarita e o outro, com o FMA Scutellospora sp. Os tratamentosforam inoculação de BSF 8; BSF 56 e controle não-inoculado com BSF. Houve uma produção diferenciada de AIA pelos solubilizadores, destacando-se a maior produção pela maioria dos isolados fúngicos. A partir do 18º dia de incubação de Scutellospora sp., foi verificado um incremento significativo do comprimento de hifas no tratamento inoculado com BSF 8. Contrariamente, o crescimento micelial de G. margarita foi inibido pelo isolado BSF 56, a partir do 24º dia de incubação.

O objetivo deste trabalho foi avaliar o efeito da densidade de inóculo de fungo micorrízico arbuscular (FMA) na incidência e severidade do Fusarium oxysporum f. sp. cubense (FOC) na bananeira, variedade 'Maçã', em fase inicial de desenvolvimento vegetativo. O trabalho foi realizado em três etapas, em condições de casa de vegetação, na Embrapa Mandioca e Fruticultura Tropical, Cruz das Almas, BA. Foi realizado um teste de ajuste para determinação das densidades de inóculo do FMA a serem utilizadas. Em seguida, o FMA, Gigaspora margarita, foi inoculado nas mudas de banana e, depois de 60 dias foi inoculado o FOC. G. margarita apresentou eficiência simbiótica no crescimento das mudas de bananeira, variedade Maçã, dependendo da densidade de inóculo. A inoculação prévia com o FMA promoveu redução no índice de infecção causado pelo FOC. A pré-colonização das plantas de bananeira pelo FMA resultou em efeito de bioproteção, modulado pela taxa de colonização micorrízica e pela concentração de inóculo do FOC no solo.This work aimed to evaluate inoculum density of arbuscular mycorrhizal fungi (AMF) on incidence and effects of Fusarium oxysporum f. sp. cubense (FOC) on Maçã variety of banana (Musa sp.) during its initial growth. An experiment was conducted at Embrapa Mandioca e Fruticultura Tropical, under greenhouse conditions, comprising three stages: a test to adjust levels of inoculum of AMF to be set on the experiment was carried out; therefore, plantlets of banana were inoculated with Gigaspora margarita and, after 60 days, they were inoculated with FOC. G. margarita was efficient for growth of banana plantlets; previous inoculation of AMF reduced disease index caused by FOC, depending on level of inoculum of AMF; previous inoculation of AMF on banana plantlets resulted in bioprotection to FOC, related to level of colonization and level of inoculum of FOC in soil.

The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal (AM) fungi from the phylum Glomeromycota. This mutualistic symbiosis provides carbohydrates to the fungus, and reciprocally improves plant phosphate uptake. AM fungal transporters can acquire phosphate from the soil through the hyphal networks. Nevertheless, the precise functions of AM fungal phosphate transporters, and whether they act as sensors or as nutrient transporters, in fungal signal transduction remain unclear. Here, we report a high-affinity phosphate transporter GigmPT from Gigaspora margarita that is required for AM symbiosis. Host-induced gene silencing of GigmPT hampers the development of G. margarita during AM symbiosis. Most importantly, GigmPT functions as a phosphate transceptor in G. margarita regarding the activation of the phosphate signaling pathway as well as the protein kinase A signaling cascade. Using the substituted-cysteine accessibility method, we identified residues A 146 (in transmembrane domain [TMD] IV) and Val 357 (in TMD VIII) of GigmPT, both of which are critical for phosphate signaling and transport in yeast during growth induction. Collectively, our results provide significant insights into the molecular functions of a phosphate transceptor from the AM fungus G. margarita . [ABSTRACT FROM AUTHOR]

Hyphal branching in the vicinity of host roots is a host recognition response of arbuscular mycorrhizal fungi. This morphological event is elicited by strigolactones. Strigolactones are carotenoid-derived terpenoids that are synthesized from carlactone and its oxidized derivatives. To test the possibility that carlactone and its oxidized derivatives might act as host-derived precolonization signals in arbuscular mycorrhizal symbiosis, carlactone, carlactonoic acid, and methyl carlactonoate as well as monohydroxycarlactones, 4-, 18-, and 19-hydroxycarlactones, were synthesized chemically and evaluated for hyphal branching-inducing activity in germinating spores of the arbuscular mycorrhizal fungus Gigaspora margarita . Hyphal branching activity was found to correlate with the degree of oxidation at C-19 methyl. Carlactone was only weakly active (100 ng/disc), whereas carlactonoic acid showed comparable activity to the natural canonical strigolactones such as strigol and sorgomol (100 pg/disc). Hydroxylation at either C-4 or C-18 did not significantly affect the activity. A series of carlactone analogues, named AD ester and AA’D diester, was synthesized by reacting formyl Meldrum’s acid with benzyl, cyclohexylmethyl, and cyclogeranyl alcohols (the A-ring part), followed by coupling of the potassium enolates of the resulting formylacetic esters with the D-ring butenolide. AD ester analogues exhibited moderate activity (1 ng–100 pg/disc), while AA’D diester analogues having cyclohexylmethyl and cyclogeranyl groups were highly active on the AM fungus (10 pg/disc). These results indicate that the oxidation of methyl to carboxyl at C-19 in carlactone is a prerequisite but BC-ring formation is not essential to show hyphal branching activity comparable to that of canonical strigolactones. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) are well known for their plant growth promoting potential and stress tolerance ability. AMF promotes plant growth even at adverse environmental conditions and improve plant nutrient uptake. This study aimed to propagate AMF using a single spore inoculation technique. Soil samples were collected from salt affected Saemangeum reclaimed land. Collected soil samples were subjected to soil analysis. In the single spore inoculation method, sorghum sudangrass ( Sorghum bicolor L.) was inoculated with a single spore. Among the 150 inoculants, six spores were able to germinate in vitro . Geminated spores were transferred to 1 kg pots containing sterilized field soil. After 120 days, the contents were mixed and transferred to 2.5 kg pots and maintained for another 120 days. After 240 days, spore count and colonization were checked. The propagated spores were identified using nested PCR followed by sequencing. The 18S rDNA sequencing of spores revealed that the spores belonged to Gigaspora margarita and Claroideoglomus lamellosum. Among the 6 inoculants, Claroideoglomus lamellosum S-11 (391 spore per 100 g of soil) had the highest spore count followed by Gigaspora margarita S-23 (235 spore per 100 g of soil). Slide method allowed visual monitoring of spore germination in vitro as well as being able to mass produce pure cultures of AMF for bio-inoculation purposes. [ABSTRACT FROM AUTHOR]

No presente trabalho, foi avaliada a influência de duas espécies de fungos micorrízicos arbusculares (FMAs) Glomus clarum e Gigaspora margarita sobre as atividades ATPásica e pirofosfatásica de microssomos obtidos por meio de fracionamento celular de raízes de milho colonizadas aos 20, 30, 40 e 60 dias do plantio. Ambos os fungos proporcionaram aumentos significativos nas atividades das ATPases e pirofosfatases; entretanto, as maiores atividades foram observadas nas raízes colonizadas pelo fungo G. clarum. Os dados cinéticos indicaram a presença de uma ativação diferencial das H+-ATPases e H+-pirofosfatases presentes nas membranas das células radiculares, dependendo da espécie fúngica e do estádio da colonização das raízes pelos FMAs. Como indicadores da eficiência da micorrização, foram avaliados a altura e o conteúdo de nutrientes na parte aérea das plantas. Os dados obtidos mostraram a primeira evidência cinética de estimulação de atividade pirofosfatásica em membranas microssomais de raízes colonizadas e descreveram um padrão inédito de ativação diferencial para a hidrólise de ATP, dependendo da espécie (G. clarum ou G. margarita) e do estádio de colonização.The influence of two species of arbuscular mycorrhizal fungi (AMF) on the ATPase and pyrophosphatase activities of corn root microsomes was investigated at 20, 30, 40, and 60 days after planting. The microsomes were isolated by cell fractionation from corn roots colonized with Glomus clarum or Gigaspora margarita. Both fungi led to a significant increase in the ATPase and pyrophosphatase activities though the highest activities were observed in roots colonized with G. clarum. Kinetics analysis suggested that mycorrhizal colonization promoted a differential regulation of the H+-ATPases and H+-PPases present in the root cell membranes. This regulation varied according to the fungal species and stage of AMF root colonization. Height and nutrient content of the plant shoot were analyzed as parameters of mycorrhization efficiency. The obtained data present the first evidence based on the kinetics of activation of pyrophosphatases in microsomal membranes from colonized roots, and describe a novel pattern for the differential activation of ATP hydrolysis depending on the fungal species (G. clarum or G. margarita) and colonization stage.

Visando a avaliar diferentes substratos na formação de mudas de bananeira e seu efeito na resposta da planta à inoculação do fungo micorrízico Gigaspora margarita, foi conduzido um experimento em estufa de aclimatação da Biofábrica CAMPO - CPA/Embrapa Mandioca e Fruticultura, Cruz das Almas, Bahia. Foram testados 13 substratos, com e sem inoculação do fungo, em plântulas na fase de aclimatação. A inoculação foi realizada no momento do transplante e, após 55 dias de cultivo, obtiveram-se dados de crescimento, nutrição mineral e colonização micorrízica. O fungo micorrízico arbuscular (FMA) Gigaspora margarita colonizou intensamente e mostrou-se benéfico para o desenvolvimento das mudas de bananeira, sendo o seu efeito modulado pelo substrato de crescimento; o substrato turfa + vermiculita + 5% de esterco destacou-se entre os melhores para a formação de mudas normais e sadias, mas só quando associado à inoculação do FMA; o uso de substrato comercial Rendmax Citrus promoveu o melhor desenvolvimento das mudas, mas inibiu a colonização e o efeito da micorriza; a complementação mineral do Rendmax Citrus não se mostrou necessária para o cultivo de mudas de bananeira; o uso de vermicomposto mostrou-se promissor para a produção de mudas de bananeira, permitindo o efeito da inoculação com FMA.

O efeito da inoculação com fungos micorrízicos arbusculares (FMA), da adubação com fósforo e da esterilização do solo sobre o crescimento de mudas de maracujazeiro amarelo foi avaliado em experimento, realizado em casa de vegetação, inteiramente casualizado em fatorial de 2 × 3 × 4, com três repetições, utilizando potes de 1,6 dm³, sendo: dois tratamentos de solo (esterilizado - SE e não esterilizado - SNE), três tratamentos de P (4, 11 e 30 mg dm-3 de P) e quatro tratamentos de inoculação (Gigaspora albida, Scutellospora heterogama, inóculo misto de G. albida, G. margarita, Acaulospora longula e S. heterogama e o controle não inoculado). Mudas inoculadas e cultivadas em SE apresentaram aumento significativo na altura, diâmetro do caule, número de folhas e de gavinhas a partir de 50 dias da inoculação (d.a.i.), com exceção das inoculadas com S. heterogama, que mostraram respostas tardias (70 d.a.i.). Maiores índices de colonização radicular e densidade de esporos na rizosfera foram registrados em SE. A esterilização do solo afetou a concentração de P na parte aérea das mudas, apenas no tratamento-controle e inoculado com S. heterogama Em geral, a esterilização do solo, a adubação fosfatada e a inoculação com FMA favoreceram o crescimento das mudas de maracujazeiro, sendo registradas interações da inoculação micorrízica, esterilização do solo e adubação fosfatada.

A river-sand culture experiment was conducted to investigate whether arbuscular mycorrhizal (AM) colonization influenced mercury (Hg) and nutrients accumulation, and whether AM fungus (AMF) Gigaspora margarita enhance host plant sengon buto (Enterolobium cyclocarpum) tolerance to Hg. Hg was applied as HgCl2 at different levels (375 and 750 µM) and added to the full strength of Hoagland's solution, then applied to seedlings in river-sands as growth media according to treatments. The non-mycorrhizal and mycorhizal E. cyclocarpum roots took up Hg, but its translocation to the leaves was inhibited. AM inoculation decreased significantly Hg content of roots seedlings by 70.5% from non-AM inoculation seedlings. Mycorrhizae enhanced significantly Ca and Mg uptake in shoot by 1.29- and 1.27-fold higher than non-mycorrhizal seedlings, but not enhanced significantly P uptake. Based on the roots dry weight, the tolerance index of non-mycorrhizal or mycorrhizal seedlings treated with 750 µM Hg supply was > 50%. It indicated that the seedlings can tolerate up to 750 µM Hg added. Considering the possible differences in AMF response to Hg in polluted soil from the field, it is not yet clear if Gi. margarita could be applied for phytoremediation of Hg in contaminated sites. Therefore, more work needs to be done using AMF isolates to reveal the possible application in the management of Hg contaminated soils.

O trabalho objetivou determinar o coeficiente de determinação genotípica (b) do mamoeiro (Carica papaya L.) quanto à capacidade de se associar e responder ao fungo micorrízico arbuscular (FMA) Gigaspora margarita. O experimento foi instalado em casa de vegetação da Embrapa Mandioca e Fruticultura, usando solo com uma dose única de fósforo (20 mg dm-3). Os tratamentos foram representados por quatro genótipos de cada um dos grupos 'Solo' e 'Formosa', mais as variedades 'Improved Sunrise Solo Line 72/12' e 'Tainung Nº 1', submetidas ou não à inoculação do fungo Gigaspora margarita. Foi utilizado um delineamento de blocos casualizados, com 4 repetições. Após a coleta dos dados, estimou-se o coeficiente "b" para os seguintes caracteres: parte aérea, comprimento de raiz, altura de planta, eficiência micorrízica e colonização. Os genótipos testados responderam à inoculação do fungo MA; os genótipos do grupo Formosa apresentaram menor comprimento de raiz; a eficiência micorrízica e a colonização radicular média para os dois grupos de plantas foram similares, situando-se em 60% e 50%, respectivamente; a inoculação aumentou a absorção de P, K e Cu, sendo esse efeito maior na variedade representante de cada grupo; o coeficiente "b" demonstrou que o melhoramento de plantas pode modular a produção de parte aérea, comprimento de raízes, altura de plantas e a eficiência micorrízica do grupo Formosa; para o grupo Solo este efeito mostrou-se mais provável para colonização radicular e menos provável para produção de parte aérea, eficiência micorrízica, comprimento de raízes e altura de plantas.

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The purpose of this study was to determine the effects of ArbuscularMycorrhizal (AM) fungi mixture-Tetranychus urticae and Glomus intraradices-T. urticae associations on gossypol concentration levels of Carmen and Stoneville cotton cultivars. The effects of treatments on gossypol synthesis were determined separately in four different plant growth periods (15, 30, 45 and 60 days after cotyledons occurring) of the two cotton mean gossypol concentration values of AM fungi and T. urticae association trials were higher than Carmen in Stoneville cultivar in 15-day old plants. Association with G. intraradices-T. urticae and AM fungi mixture-T. urticae produced significant effects in the 30-day old plants in both cotton cultivars (P < 0.05). In 45-day old plants, no differences were found in the mean gossypol concentration values of AM fungi and T. urticae association in G. intraradices treatment for both cotton cultivars. Whereas mean gossypol concentrations of the G. intraradices trials were not different from each other in Carmen cultivar in 60-day old plants, mean value determined in AM fungi mixture (0.709 ± 0.080 (ig/mL) in Stoneville cultivar was different from the other trials (P < 0.05). [ABSTRACT FROM AUTHOR]

A major strigolactone produced by the model legume Medicago truncatula (barrel medic) has been tentatively identified as a didehydro-orobanchol isomer. In this study, a putative didehydro-orobanchol isomer was isolated from root exudates collected from barrel medic grown hydroponically under phosphate-starved conditions. The structure and absolute configurations of this strigolactone, named medicaol, were determined by a combination of spectroscopic analysis and spectral comparison with 4-deoxymedicaol which was synthesized using solvolysis and rearrangement of hydroxymethylhexahydroindenone to tetrahydroazulenone as a key step. Medicaol has a seven-membered cycloheptadiene in the A ring instead of a typical six-membered cyclohexene. Medicaol and 4-deoxymedicaol showed activity comparable to their corresponding six-membered A ring relatives, orobanchol and 4-deoxyorobanchol ( ent -2′- epi -5-deoxystrigol), in inducing hyphal branching of germinating spores of an arbuscular mycorrhizal fungus Gigaspora margarita . Plausible biosynthetic pathways from 4-deoxyorobanchol to medicaol are also proposed. [ABSTRACT FROM AUTHOR]

The potential effects of arbuscular mycorrhizal fungi (AMF) on growth, nutrient assimilation, and inoculation effectiveness of AMF on the pioneer plant Miscanthus sacchariflorus which is dominant in river banks were evaluated. A pot experiment was performed in a greenhouse at Saitama University, Japan. Spores of AMF strains were collected from the commercial product ‘Serakinkon’. The average colonization level of M. sacchariflorus was 23–28%, whereas no colonization was found in sterilized soil. AMF colonization increased the chlorophyll content, plant dry mass, N, P, K, Mg, Fe, Cu, and Zn concentration of the M. sacchariflorus plant’s roots, stems, and leaves when it was applied with natural and sterilized soil. In all cases, maximum values were measured when the M. sacchariflorus plant was applied with natural soil in combination with AMF, but Ca concentration decreased as colonization level increased. Mn concentration decreased in roots and stems but increased in leaves in natural soil, and AMF with natural soil treatment. N loss minimization from the soil was significant when colonization level was high. Therefore, AMF have some potential effects for growth of the C4 grass Miscanthus sacchariflorus and nitrogen retention in aquatic–terrestrial inter-faces (river banks). [ABSTRACT FROM AUTHOR]

The objective of this work is to analyze the growth of coffee seedlings inoculated with mycorrhizal fungi, through the analysis of plant growth. The experimental design was completely randomized in a 2×6 factorial design, with control and inoculated seedlings six evaluation periods, with six replications. Catuaí Vermelho IAC 99 seeds were desinfested and germinated in autoclaved sand. After 75 days, at the time of transplanting, half of the seedlings were inoculated by applying spores of species Glomus clarum and Gigaspora margarita. At the time of inoculation (0) and at 30, 60, 90, 120 and 150 days plant height and leaf area were measured, and subsequent determination of total and leaf dry mass. The data were extrapolated to determine the measures of non-linear growth analysis. In general, the inoculated plants showed a negative effect on early growth, but at the end of the experiment had superior growth than uninoculated seedlings. Growth analysis enabled a better understanding of the association, and found that despite the increased investment in morphology for energy harvesting, there was no increase in net assimilation rate and may consider that initially fungi represented drain assimilated, but in the end the seedlings inoculated grew up. The association may be considered to be a sink while the plants do not have leaf area enough to maintain the association, leading to reduction in the liquid photosynthetic rate. This sink ends later, and there is a net benefit for the seedlings, at the end of the production period. [ABSTRACT FROM AUTHOR]

• Arbuscular mycorrhiza (AM) is an ecologically relevant symbiosis between most land plants and Glomeromycota fungi. The peculiar traits of AM fungi have so far limited traditional approaches such as genetic transformation. The aim of this work was to investigate whether the protein transduction domain of the HIV-1 transactivator of transcription (TAT) protein, previously shown to act as a potent nanocarrier for macromolecule delivery in both animal and plant cells, may translocate protein cargoes into AM fungi. • We evaluated the internalization into germinated spores of Gigaspora margarita of two recombinant TAT fusion proteins consisting of either a fluorescent (GFP) or a luminescent (aequorin) reporter linked to the TAT peptide. • Both TAT-fused proteins were found to enter AM fungal mycelia after a short incubation period (5-10 min). Ca2+ measurements in G. margarita mycelia pre-incubated with TAT-aequorin demonstrated the occurrence of changes in the intracellular free Ca2+ concentration in response to relevant stimuli, such as touch, cold, salinity, and strigolactones, symbiosis-related plant signals. • These data indicate that the cell-penetrating properties of the TAT peptide can be used as an effective strategy for intracellularly delivering proteins of interest and shed new light on Ca2+ homeostasis and signalling in AM fungi. [ABSTRACT FROM AUTHOR]

Effects have been investigated of reduced C supply (induced by shade) on arbuscular mycorrhizal (AM) colonisation, mycorrhizal growth responses (MGRs) and on AM-mediated and direct uptake of phosphate (Pi) (using P) in wheat, a plant that does not usually respond positively to AM colonisation. Shading markedly reduced growth and shoot/root dry weight ratios of both AM and non-mycorrhizal wheat, indicating decreased photosynthetic C supply. However, shading had very little effect on percent root length colonised by Rhizophagus irregularis or Gigaspora margarita or on MGRs, which remained slightly positive or zero, regardless of shade; there were no growth depressions under shade. By 6 weeks, when the contributions of the AM pathway were measured with P supplied in small hyphal compartments, R. irregularis had supplied 23 to 28 % of shoot P with no significant effect of shading. Data show that reduced C availability did not reduce the contribution of the AM pathway to plant P, so the fungi were not acting physiologically as parasites. These results support our previous hypothesis that lack of positive MGR is not necessarily the outcome of excessive C use by the fungi or failure to deliver P via the AM pathway. [ABSTRACT FROM AUTHOR]

Interactions between arbuscular mycorrhizal fungal ( AMF) species cocolonizing the same host plant are still little understood in spite of major ecological significance of mycorrhizal symbiosis and widespread occurrence of these fungi in communities rather than alone. Furthermore, shifting the composition of AMF communities has demonstrated consequences for the provision of symbiotic benefits to the host as well as for the qualities of ecosystem services. Therefore, here we addressed the nature and strength of interactions between three different AMF species in all possible two-species combinations on a gradient of inoculation densities. Fungal communities were established in pots with Medicago truncatula plants, and their composition was assessed with taxon-specific real-time PCR markers. Nature of interactions between the fungi was varying from competition to facilitation and was influenced by both the identity and relative abundance of the coinoculated fungi. Plants coinoculated with Claroideoglomus and Rhizophagus grew bigger and contained more phosphorus than with any of these two fungi separately, although these fungi obviously competed for root colonization. On the other hand, plants coinoculated with Gigaspora and Rhizophagus, which facilitated each other's root colonization, grew smaller than with any of these fungi separately. Our results point to as yet little understood complexity of interactions in plant-associated symbiotic fungal communities, which, depending on their composition, can induce significant changes in plant host growth and/or phosphorus acquisition in either direction. [ABSTRACT FROM AUTHOR]