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1.
J Sci Food Agric ; 102(2): 540-549, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34146349

RESUMO

BACKGROUND: Pasture farming in south-western Australia is challenged by nutrient-poor soils. We assessed the impact of microbial consortium inoculant (MI) and rock mineral fertiliser (MF) on growth, nutrient uptake, root morphology, rhizosphere carboxylate exudation and mycorrhizal colonisation in three pasture grasses - tall fescue (Festuca arundinacea L.), veldt grass (Ehrharta calycina Sm.) and tall wheatgrass (Thinopyrum ponticum L.) grown in low-phosphorus (P) sandy soil in a glasshouse for 30 and 60 days after sowing (DAS). RESULTS: Veldt grass produced the highest specific root length and smallest average root diameter in both growth periods, and had similar shoot weight, root surface area and fine root length (except at 30 DAS) to tall fescue. Compared with the control, MI alone or combined with MF significantly increased shoot and root biomass (except root biomass at 30 DAS), likely due to the significant increases in root surface area and fine root length. Plants supplied with MI + MF had higher shoot N and P contents than those in the MI and the control treatments at 60 DAS. Malate, citrate and trans-aconitate were the major rhizosphere carboxylates exuded at both 30 and 60 DAS. Malate exudation varied among species and treatments in both growth periods, but citrate exudation was consistently higher in the low-P treatments (control and MI) than the MF and MI + MF treatments. CONCLUSION: Microbial consortium inoculant can positively influence pasture production in low-P soil by increasing root surface area and fine root length, whereas exudation of nutrient-mobilising carboxylates (citrate) is dependent more on soil P supply than microbial consortium inoculant. © 2021 Society of Chemical Industry.


Assuntos
Inoculantes Agrícolas/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Fósforo/análise , Exsudatos de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Poaceae/microbiologia , Ácidos Carboxílicos/análise , Ácidos Carboxílicos/metabolismo , Fertilizantes/análise , Consórcios Microbianos , Fósforo/metabolismo , Exsudatos de Plantas/análise , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Poaceae/química , Poaceae/crescimento & desenvolvimento , Poaceae/metabolismo , Rizosfera , Solo/química
2.
BMC Plant Biol ; 21(1): 498, 2021 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-34715790

RESUMO

BACKGROUND: Effects on maize were assessed of dual inoculation with arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) isolated from other plant species. METHODS: Suspensions of DSE isolated from Stipa krylovii were prepared at different densities (2, 4, and 8 × 105 CFU mL- 1) and inoculated separately (AMF or DSE) or together (AMF + DSE), to explore their effects on maize growth. RESULTS: Inoculation with AMF or medium and high densities of DSE and combined inoculation (AMF + DSE) increased plant above-ground growth and altered root morphology. Differences in plant growth were attributable to differences in DSE density, with negative DSE inoculation responsiveness at low density. AMF promoted plant above-ground growth more than DSE and the high density of DSE promoted root development more than AMF. Combined inoculation might lead to synergistic growth effects on maize at low density of DSE and competitive effects at medium and high DSE densities. CONCLUSIONS: AMF and DSE co-colonized maize roots and they had positive effects on the host plants depending on DSE density. These findings indicate the optimum maize growth-promoting combination of AMF and DSE density and provide a foundation for further exploration of potentially synergistic mechanisms between AMF and DSE in physiological and ecological effects on host plants.


Assuntos
Endófitos/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Simbiose/fisiologia , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/microbiologia
3.
PLoS Biol ; 19(7): e3001326, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34260583

RESUMO

Arbuscular mycorrhiza (AM) are mutualistic interactions formed between soil fungi and plant roots. AM symbiosis is a fundamental and widespread trait in plants with the potential to sustainably enhance future crop yields. However, improving AM fungal association in crop species requires a fundamental understanding of host colonisation dynamics across varying agronomic and ecological contexts. To this end, we demonstrate the use of betalain pigments as in vivo visual markers for the occurrence and distribution of AM fungal colonisation by Rhizophagus irregularis in Medicago truncatula and Nicotiana benthamiana roots. Using established and novel AM-responsive promoters, we assembled multigene reporter constructs that enable the AM-controlled expression of the core betalain synthesis genes. We show that betalain colouration is specifically induced in root tissues and cells where fungal colonisation has occurred. In a rhizotron setup, we also demonstrate that betalain staining allows for the noninvasive tracing of fungal colonisation along the root system over time. We present MycoRed, a useful innovative method that will expand and complement currently used fungal visualisation techniques to advance knowledge in the field of AM symbiosis.


Assuntos
Betalaínas/metabolismo , Micorrizas/crescimento & desenvolvimento , Genes Fúngicos , Marcadores Genéticos , Medicago truncatula/microbiologia , Micorrizas/genética , Micorrizas/metabolismo , Raízes de Plantas/microbiologia , Regiões Promotoras Genéticas , Simbiose/genética , Tabaco/genética , Tabaco/microbiologia
4.
Sci Rep ; 11(1): 13491, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34188188

RESUMO

Ascophyllum nodosum extracts (ANE) are well-established plant biostimulants that improve stress tolerance and crop vigour, while also having been shown to stimulate soil microbes. The intersection of these two stimulatory activities, and how they combine to enhance plant health, however, remains poorly understood. In the present study, we aimed to evaluate: (1) the direct effect of ANE on the arbuscular mycorrhizal fungus Rhizophagus irregularis, and (2) whether ANE influences endomycorrhization in plants. ANE enhanced development of R. irregularis in vitro, showing greater spore germination, germ tube length, and hyphal branching. Greenhouse-grown Medicago truncatula drench-treated with ANE formed mycorrhizal associations faster (3.1-fold higher mycorrhization at week 4) and grew larger (29% greater leaf area by week 8) than control plants. Foliar applications of ANE also increased root colonization and arbuscular maturity, but did not appear to enhance plant growth. Nonetheless, following either foliar or drench application, M. truncatula genes associated with establishment of mycorrhizae were expressed at significantly higher levels compared to controls. These results suggest that ANE enhances mycorrhization through both direct stimulation of arbuscular mycorrhizal fungus growth and through stimulation of the plant's accommodation of the symbiont, together promoting the establishment of this agriculturally vital plant-microbe symbiosis.


Assuntos
Ascophyllum/química , Misturas Complexas/farmacologia , Fungos/crescimento & desenvolvimento , Medicago truncatula , Micorrizas/crescimento & desenvolvimento , Misturas Complexas/química , Medicago truncatula/crescimento & desenvolvimento , Medicago truncatula/microbiologia
5.
Sci Rep ; 11(1): 11319, 2021 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-34059696

RESUMO

Target of rapamycin (TOR) is a conserved central growth regulator in eukaryotes that has a key role in maintaining cellular nutrient and energy status. Arbuscular mycorrhizal (AM) fungi are mutualistic symbionts that assist the plant in increasing nutrient absorption from the rhizosphere. However, the role of legume TOR in AM fungal symbiosis development has not been investigated. In this study, we examined the function of legume TOR in the development and formation of AM fungal symbiosis. RNA-interference-mediated knockdown of TOR transcripts in common bean (Phaseolus vulgaris) hairy roots notably suppressed AM fungus-induced lateral root formation by altering the expression of root meristem regulatory genes, i.e., UPB1, RGFs, and sulfur assimilation and S-phase genes. Mycorrhized PvTOR-knockdown roots had significantly more extraradical hyphae and hyphopodia than the control (empty vector) roots. Strong promoter activity of PvTOR was observed at the site of hyphal penetration and colonization. Colonization along the root length was affected in mycorrhized PvTOR-knockdown roots and the arbuscules were stunted. Furthermore, the expression of genes induced by AM symbiosis such as SWEET1, VPY, VAMP713, and STR was repressed under mycorrhized conditions in PvTOR-knockdown roots. Based on these observations, we conclude that PvTOR is a key player in regulating arbuscule development during AM symbiosis in P. vulgaris. These results provide insight into legume TOR as a potential regulatory factor influencing the symbiotic associations of P. vulgaris and other legumes.


Assuntos
Micorrizas/crescimento & desenvolvimento , Phaseolus/enzimologia , Phaseolus/microbiologia , Serina-Treonina Quinases TOR/metabolismo , Regulação da Expressão Gênica de Plantas , Hifas/crescimento & desenvolvimento , Especificidade de Órgãos , Plantas Geneticamente Modificadas , Simbiose
6.
Methods Mol Biol ; 2309: 75-89, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34028680

RESUMO

Strigolactones (SLs) are components of root exudates as a consequence of active release from the roots into the soil. Notably, they have been described as stimulants of seed germination in parasitic plants and of the presymbiotic growth in arbuscular mycorrhizal (AM) fungi, which are a crucial component of the plant root beneficial microbiota. SLs have therefore the potential to influence other microbes that proliferate in the soil around the roots and may interact with plants. A direct effect of SL analogs on the in vitro growth of a number of saprotrophic or plant pathogenic fungi was indeed reported.Here we describe a standardized method to evaluate the effect of SLs or their synthetic analogs on AM and filamentous fungi. For AM fungi, we propose a spore germination assay since it is more straightforward than the hyphal branching assay and it does not require deep expertise and skills. For filamentous fungi that can grow in axenic cultures, we describe the assay based on SLs embedded in the solid medium or dissolved in liquid cultures where the fungus is inoculated to evaluate the effect on growth, hyphal branching or conidia germination. These assays are of help to test the activity of natural SLs as well as of newly designed SL analogs for basic and applied research.


Assuntos
Bioensaio , Fungos/efeitos dos fármacos , Compostos Heterocíclicos com 3 Anéis/farmacologia , Lactonas/farmacologia , Micorrizas/efeitos dos fármacos , Reguladores de Crescimento de Plantas/farmacologia , Sementes/microbiologia , Esporos Fúngicos/efeitos dos fármacos , Trifolium/microbiologia , Fungos/crescimento & desenvolvimento , Compostos Heterocíclicos com 3 Anéis/síntese química , Lactonas/síntese química , Micorrizas/crescimento & desenvolvimento , Reguladores de Crescimento de Plantas/síntese química , Esporos Fúngicos/crescimento & desenvolvimento
7.
Methods Mol Biol ; 2309: 157-177, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34028686

RESUMO

Arbuscular mycorrhiza is an ancient symbiosis between most land plants and fungi of the Glomeromycotina, in which the fungi provide mineral nutrients to the plant in exchange for photosynthetically fixed organic carbon. Strigolactones are important signals promoting this symbiosis, as they are exuded by plant roots into the rhizosphere to stimulate activity of the fungi. In addition, the plant karrikin signaling pathway is required for root colonization. Understanding the molecular mechanisms underpinning root colonization by AM fungi, requires the use of plant mutants as well as treatments with different environmental conditions or signaling compounds in standardized cocultivation systems to allow for reproducible root colonization phenotypes. Here we describe how we set up and quantify arbuscular mycorrhiza in the model plants Lotus japonicus and Brachypodium distachyon under controlled conditions. We illustrate a setup for open pot culture as well as for closed plant tissue culture (PTC) containers, for plant-fungal cocultivation in sterile conditions. Furthermore, we explain how to harvest, store, stain, and image AM roots for phenotyping and quantification of different AM structures.


Assuntos
Bioensaio , Brachypodium/microbiologia , Compostos Heterocíclicos com 3 Anéis/farmacologia , Lactonas/farmacologia , Lotus/microbiologia , Micorrizas/efeitos dos fármacos , Reguladores de Crescimento de Plantas/farmacologia , Raízes de Plantas/microbiologia , Brachypodium/crescimento & desenvolvimento , Lotus/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Fenótipo , Raízes de Plantas/crescimento & desenvolvimento
8.
Plant Mol Biol ; 106(4-5): 319-334, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33825084

RESUMO

KEY MESSAGE: Overexpression of genes involved in coumarin production and secretion can mitigate mycorrhizal incompatibility in nonhost Arabidopsis plants. The coumarin scopoletin, in particular, stimulates pre-penetration development and metabolism in mycorrhizal fungi. Although most plants can benefit from mutualistic associations with arbuscular mycorrhizal (AM) fungi, nonhost plant species such as the model Arabidopsis thaliana have acquired incompatibility. The transcriptional response of Arabidopsis to colonization by host-supported AM fungi switches from initial AM recognition to defense activation and plant growth antagonism. However, detailed functional information on incompatibility in nonhost-AM fungus interactions is largely missing. We studied interactions between host-sustained AM fungal networks of Rhizophagus irregularis and 18 Arabidopsis genotypes affected in nonhost penetration resistance, coumarin production and secretion, and defense (salicylic acid, jasmonic acid, and ethylene) and growth hormones (auxin, brassinosteroid, cytokinin, and gibberellin). We demonstrated that root-secreted coumarins can mitigate incompatibility by stimulating fungal metabolism and promoting initial steps of AM colonization. Moreover, we provide evidence that major molecular defenses in Arabidopsis do not operate as primary mechanisms of AM incompatibility nor of growth antagonism. Our study reveals that, although incompatible, nonhost plants can harbor hidden tools that promote initial steps of AM colonization. Moreover, it uncovered the coumarin scopoletin as a novel signal in the pre-penetration dialogue, with possible implications for the chemical communication in plant-mycorrhizal fungi associations.


Assuntos
Arabidopsis/microbiologia , Fungos/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Escopoletina/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Genes de Plantas , Genótipo , Interações entre Hospedeiro e Microrganismos/genética , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Transdução de Sinais
9.
J Sci Food Agric ; 101(14): 5834-5841, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33788958

RESUMO

BACKGROUND: The harmful effect of chemical fertilizer application on human health and the environment as a modern method of meeting the food demand of the increasing world population demands an urgent alternative that is environmentally friendly, which will pose no harm to human health and the environment. Arbuscular mycorrhizal fungi (AMF) are beneficial soil microorganisms that provide various ecological functions in increasing soil fertility and enhancing plant growth. This present study aimed to propagate, characterize and examine the effect of viable arbuscular mycorrhizal fungal spores on maize (Zea mays L) hosts using molecular methods. The propagation of AMF in the host plant using sterile soil and vermiculite was conducted in the greenhouse. RESULT: The effect of AMF inoculation revealed a significant difference (P > 0.05) in maize growth, root colonization and AMF spore count when compared with the control. In all the parameters measured in this study, all the AMF spores propagated had a positive effect on the maize plant over the control, with the highest value mostly recorded in Rhizophagus irregularis AOB1. The molecular characterization of the spore using a specific universal primer for Glomeromycota established the success of the propagation process, which enhanced the classification of the AMF species into Rhizophagus irregularis OAB1, Glomus mosseae OAB2 and Paraglomus occultum OAB3. CONCLUSION: This finding will be a starting point in producing arbuscular mycorrhizal inoculum as a biofertilizer to enhance plant growth promotion. © 2021 Society of Chemical Industry.


Assuntos
Fungos/isolamento & purificação , Micorrizas/isolamento & purificação , Esporos Fúngicos/crescimento & desenvolvimento , Zea mays/microbiologia , Fungos/classificação , Fungos/genética , Fungos/crescimento & desenvolvimento , Micorrizas/classificação , Micorrizas/genética , Micorrizas/crescimento & desenvolvimento , Filogenia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Microbiologia do Solo , Esporos Fúngicos/classificação , Esporos Fúngicos/genética , Esporos Fúngicos/isolamento & purificação , Zea mays/crescimento & desenvolvimento
10.
Sci Rep ; 11(1): 3645, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33574436

RESUMO

Plants host diverse microbial communities, but there is little consensus on how we sample these communities, and this has unknown consequences. Using root and leaf tissue from showy milkweed (Asclepias speciosa), we compared two common sampling strategies: (1) homogenizing after subsampling (30 mg), and (2) homogenizing bulk tissue before subsampling (30 mg). We targeted bacteria, arbuscular mycorrhizal (AM) fungi and non-AM fungi in roots, and foliar fungal endophytes (FFE) in leaves. We further extracted DNA from all of the leaf tissue collected to determine the extent of undersampling of FFE, and sampled FFE twice across the season using strategy one to assess temporal dynamics. All microbial groups except AM fungi differed in composition between the two sampling strategies. Community overlap increased when rare taxa were removed, but FFE and bacterial communities still differed between strategies, with largely non-overlapping communities within individual plants. Increasing the extraction mass 10 × increased FFE richness ~ 10 ×, confirming the severe undersampling indicated in the sampling comparisons. Still, seasonal patterns in FFEs were apparent, suggesting that strong drivers are identified despite severe undersampling. Our findings highlight that current sampling practices poorly characterize many microbial groups, and increased sampling intensity is necessary for increase reproducibility and to identify subtler patterns in microbial distributions.


Assuntos
Microbiota/genética , Micorrizas/genética , Plantas/microbiologia , Microbiologia do Solo , Micorrizas/classificação , Micorrizas/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Simbiose/genética
11.
Ecotoxicol Environ Saf ; 213: 112042, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33607336

RESUMO

Aluminum (Al) toxicity severely decreases plant growth and productivity in acidic soil globally. Ectomycorrhizal (ECM) fungi can promote host plant's Al-tolerance by acting as a physical barrier or bio-filter. However, little information is available on the role of ECM fungus on Al immobilization with respect to Al-tolerance. This present study aimed to screen a promising indigenous ECM fungus with high Al-tolerance and to understand its role in Al immobilization related to Al-tolerance. Two ECM fungal strains (Lactarius deliciosus 2 and Pisolithus tinctorius 715) isolated from forest stands in Southwest China were cultured in vitro with 0.0, 1.0 or 2.0 mM Al addition for 21 days to compare their Al accumulation and Al-tolerance. Meanwhile, fungal mycelia were incubated in 0.037 mM Al3+ solutions, and then Al3+ concentrations in the solution were determined at time 2, 5, 10, 20, 40, 60, 120, 180, and 240 min, and the Al3+ immobilization characteristics were evaluated using the pseudo-first order, pseudo-second order and intraparticle diffusion models. Results showed that 1.0 or 2.0 mM Al3+ addition significantly increased fungal biomass production by 23% or 41% in L. deliciosus 2, not in P. tinctorius 715. Fungal Al3+ concentrations in L. deliciosus 2 and P. tinctorius 715 were significantly increased by 293% and 103% under 2.0 mM than under 1.0 mM Al3+ addition. The pH values in the culture solution were significantly decreased by 0.43 after 21 d fungus growth but no changes between these two fungi under the same Al3+ addition. Fungal Al3+ immobilization showed a three-stage trend with initially a rapid rate followed a relatively slower rate until reaching equilibrium. The pseudo-second order model was the best (R2 = 0.98 and 0.99 for L. deliciosus 2 and P. tinctorius 715) to fit the experimentally observed data among the three models. Compared to P. tinctorius 715, L. deliciosus 2 also had greater intercept value, cation exchange capacity (CEC), and extracellular Al3+ proportion in fungal mycelia. Additionally, bio-concentration on Al3+, active site numbers for Al3+, boundary layer thickness, CEC, and immobilization on the cell wall in fungal mycelia were involved in ECM fungal Al-tolerance. These results show that both ECM fungi are Al-tolerant while L. deliciosus 2 is a promising indigenous ECM isolate with higher Al-tolerance in Southwest China, and they can be hence applied to the afforestation and ecological restoration in acidic soil.


Assuntos
Alumínio/metabolismo , Basidiomycota/fisiologia , Poluentes do Solo/metabolismo , Agaricales , Basidiomycota/crescimento & desenvolvimento , Biodegradação Ambiental , Biomassa , China , Florestas , Micélio/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Micorrizas/fisiologia , Solo/química , Microbiologia do Solo
12.
Plant Cell Physiol ; 62(2): 306-320, 2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33386853

RESUMO

The formation of arbuscular mycorrhizal (AM) symbiosis requires plant root host cells to undergo major structural and functional reprogramming to house the highly branched AM fungal structure for the reciprocal exchange of nutrients. These morphological modifications are associated with cytoskeleton remodelling. However, molecular bases and the role of microtubules (MTs) and actin filament dynamics during AM formation are largely unknown. In this study, the tomato tsb (tomato similar to SB401) gene, belonging to a Solanaceae group of genes encoding MT-associated proteins (MAPs) for pollen development, was found to be highly expressed in root cells containing arbuscules. At earlier stages of mycorrhizal development, tsb overexpression enhanced the formation of highly developed and transcriptionally active arbuscules, while tsb silencing hampers the formation of mature arbuscules and represses arbuscule functionality. However, at later stages of mycorrhizal colonization, tsb overexpressing (OE) roots accumulate fully developed transcriptionally inactive arbuscules, suggesting that the collapse and turnover of arbuscules might be impaired by TSB accumulation. Imaging analysis of the MT cytoskeleton in cortex root cells OE tsb revealed that TSB is involved in MT bundling. Taken together, our results provide unprecedented insights into the role of novel MAP in MT rearrangements throughout the different stages of the arbuscule life cycle.


Assuntos
Lycopersicon esculentum/metabolismo , Microtúbulos/fisiologia , Micorrizas/crescimento & desenvolvimento , Proteínas de Plantas/fisiologia , Genes de Plantas/genética , Genes de Plantas/fisiologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Microtúbulos/metabolismo , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/fisiologia , Alinhamento de Sequência , Simbiose
13.
Mol Biol Rep ; 48(1): 527-538, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33389542

RESUMO

Under natural conditions, mycorrhizal symbiosis accompanies nearly the entire life cycle of orchids from seed germination through to flowering and fruiting. Tulasnella-like orchid mycorrhizal fungi are the most common mycorrhizal fungi found in association with orchid species. Presently suitable reference genes have not been systematically selected for the quantification of gene expression via Real-Time Quantitative Reverse Transcription PCR (RT-qPCR). We evaluated 12 candidate Tulasnella genes in nine different Tulasnella isolates and in the Dendrobium-fungal symbiotic germination associations followed by statistical analysis using the programs Bestkeeper, geNorm, and Normfinder to analyze the expression stability of the individual genes. The results showed that the EF2, UBC, and PP2A genes had the highest rankings with relatively stable expression levels across the different genotypes and during the symbiotic seed germination process by the three programs, and may be suitable for RT-qPCR normalization. Furthermore, the gene encoding C-5 Sterol desaturase (C5SD) was selected to verify the reliability of EF2, UBC, and PP2A expression during the Tulasnella-Dendrobium symbiotic seed germination process. This study is the first systematic exploration of optimal reference genes for gene expression studies during the colonization of orchid seeds by the mycorrhizal fungus Tulasnella.


Assuntos
Basidiomycota/genética , Micorrizas/genética , Orchidaceae/genética , Oxirredutases/genética , Simbiose/genética , Basidiomycota/crescimento & desenvolvimento , Flores/genética , Flores/crescimento & desenvolvimento , Frutas/genética , Frutas/crescimento & desenvolvimento , Germinação/genética , Micorrizas/crescimento & desenvolvimento , Orchidaceae/crescimento & desenvolvimento , Orchidaceae/microbiologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Padrões de Referência
14.
Sci Rep ; 11(1): 1100, 2021 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-33441780

RESUMO

Arbuscular mycorrhizal (AM) symbioses are an attractive means of improving the efficiency of soil phosphorus (P) that difficult to be used by plants and may provide a sustainable way of maintaining high yields while reducing P applications. However, quantifying the contribution of indigenous AM fungi on phosphorus uptake and yields of maize (Zea mays L.) under field conditions is not particularly clear. Mesh-barrier compartments were applied to monitor the distribution of hyphal P uptake throughout the experimental period under different planting densities and soil depths, over two consecutive years. AM symbioses enhanced plant P-acquisition efficiency, especially during the silking stage, and hyphae of AM fungi was assessed to contribution 19.4% at most to total available P content of soil. Moreover, the pattern of AM depletion of soil P generally matched shoot nutrient demand under the high planting density, which resulted in significantly increased yield in 2014. Although the hyphal length density was significantly decreased with soil depth, AM fungi still had high potential for P supply in deeper soil. It demonstrates the great potential of indigenous AM fungi to maize productivity in the high-yield area of China, and it would further provide the possibility of elimination P fertilizer applications to maintain high yields.


Assuntos
Micorrizas/metabolismo , Fósforo/metabolismo , Zea mays/metabolismo , Transporte Biológico , China , Produção Agrícola , Micorrizas/crescimento & desenvolvimento , Fósforo/análise , Solo/química , Zea mays/crescimento & desenvolvimento
15.
PLoS One ; 15(11): e0241794, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33152013

RESUMO

Whereas the role of arbuscular mycorrhizal fungi (AMF) in plant growth improvement has been well described in agroecosystems, little is known about the effect of environmental factors on AMF root colonization status of barley, the fourth most important cereal crop all over the world. In order to understand the influence of environmental factors, such as climatic and soil physico-chemical properties, on the spontaneous mycorrhizal ability of barley (Hordeum vulgare L.), a field investigation was conducted in 31 different sites in sub-humid, upper and middle semi-arid areas of Northern Tunisia. Mycorrhizal root colonization of H. vulgare varied considerably among sites. Principal component analysis showed that barley mycorrhization is influenced by both climatic and edaphic factors. A partial least square structural equation modelling (PLS-SEM) revealed that 39% (R²) of the total variation in AMF mycorrhizal rate of barley roots was mainly explained by chemical soil properties and climatic characteristics. Whereas barley root mycorrhizal rates were inversely correlated with soil organic nitrogen (ON), available phosphorus amounts (P), altitude (Z), average annual rainfall (AAR), they were directly correlated with soil pH and temperature. Our results indicated that AMF root colonization of barley was strongly related to climatic characteristics than chemical soil properties. The current study highlights the importance of the PLS-SEM to understand the interactions between climate, soil properties and AMF symbiosis of barley in field conditions.


Assuntos
Hordeum/microbiologia , Micorrizas/crescimento & desenvolvimento , Solo/química , Hordeum/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Análise de Componente Principal , Chuva , Microbiologia do Solo , Temperatura , Tunísia
16.
Genes (Basel) ; 11(11)2020 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-33143066

RESUMO

Mycorrhizal desert truffles such as Terfezia boudieri, Tirmania nivea, and Terfezia claveryi, form mycorrhizal associations with plants of the Cistaceae family. These valued truffles are still collected from the wild and not cultivated under intensive farming due to the lack of basic knowledge about their biology at all levels. Recently, several genomes of desert truffles have been decoded, enabling researchers to attempt genetic manipulations to enable cultivation. To execute such manipulations, the development of molecular tools for genes transformation into truffles is needed. We developed an Agrobacterium tumefaciens-mediated genetic transformation system in T. boudieri. This system was optimized for the developmental stage of the mycelia explants, bacterial optical density, infection and co-cultivation durations, and concentrations of the selection antibiotics. The pFPL-Rh plasmid harboring hph gene conferring hygromycin resistance as a selection marker and the red fluorescent protein gene were used as visual reporters. The optimal conditions were incubation with 200 µM of acetosyringone, attaining a bacterial optical density of 0.3 OD600; transfer time of 45 min; and co-cultivation for 3 days. This is the first report on a transformation system for T. boudieri, and the proposed protocol can be adapted for the transformation of other important desert truffles as well as ectomycorrhizal species.


Assuntos
Agrobacterium tumefaciens/genética , Ascomicetos/genética , Transformação Genética/genética , Agrobacterium tumefaciens/crescimento & desenvolvimento , Ascomicetos/crescimento & desenvolvimento , Cistaceae/microbiologia , Engenharia Genética/métodos , Micélio/genética , Micélio/crescimento & desenvolvimento , Micorrizas/genética , Micorrizas/crescimento & desenvolvimento
17.
BMC Microbiol ; 20(1): 304, 2020 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-33045991

RESUMO

BACKGROUND: Establishing mixed plantations is an effective way to improve soil fertility and increase forest productivity. Arbuscular mycorrhizal (AM) fungi are obligate symbiotic fungi that can promote mineral nutrient absorption and regulate intraspecific and interspecific competition in plants. However, the effects of mixed plantations on the community structure and abundance of AM fungi are still unclear. Illumina MiSeq sequencing was used to investigate the AM fungal community in the roots and soils of pure and mixed plantations (Juglans mandshurica × Larix gmelinii). The objective of this study is to compare the differential responses of the root and rhizosphere soil AM fungal communities of Juglans mandshurica to long-term mixed plantation management. RESULTS: Glomus and Paraglomus were the dominant genera in the root samples, accounting for more than 80% of the sequences. Compared with that in the pure plantation, the relative abundance of Glomus was higher in the mixed plantation. Glomus, Diversispora and Paraglomus accounted for more than 85% of the sequences in the soil samples. The relative abundances of Diversispora and an unidentified genus of Glomeromycetes were higher and lower in the pure plantation, respectively. The Root_P samples (the roots in the pure plantation) had the highest number of unique OTUs (operational taxonomic units), which belonged mainly to an unidentified genus of Glomeromycetes, Paraglomus, Glomus and Acaulospora. The number of unique OTUs detected in the soil was lower than that in the roots. In both the root and soil samples, the forest type did not have a significant effect on AM fungal diversity, but the Sobs value and the Shannon, Chao1 and Ace indices of AM fungi in the roots were significantly higher than those in the soil. CONCLUSIONS: Mixed forest management had little effect on the AM fungal community of Juglans mandshurica roots and significantly changed the community composition of the soil AM fungi, but not the diversity.


Assuntos
Fungos/classificação , Juglans/microbiologia , Larix/microbiologia , Consórcios Microbianos/fisiologia , Micorrizas/crescimento & desenvolvimento , Rizosfera , China , Conservação dos Recursos Naturais/métodos , DNA Fúngico/genética , Fungos/genética , Fungos/isolamento & purificação , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Juglans/crescimento & desenvolvimento , Larix/crescimento & desenvolvimento , Técnicas de Tipagem Micológica , Solo/química , Microbiologia do Solo
18.
Proc Natl Acad Sci U S A ; 117(41): 25779-25788, 2020 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-32999061

RESUMO

Arbuscular mycorrhizal (AM) fungi, forming symbiotic associations with land plants, are obligate symbionts that cannot complete their natural life cycle without a host. The fatty acid auxotrophy of AM fungi is supported by recent studies showing that lipids synthesized by the host plants are transferred to the fungi, and that the latter lack genes encoding cytosolic fatty acid synthases. Therefore, to establish an asymbiotic cultivation system for AM fungi, we tried to identify the fatty acids that could promote biomass production. To determine whether AM fungi can grow on medium supplied with fatty acids or lipids under asymbiotic conditions, we tested eight saturated or unsaturated fatty acids (C12 to C18) and two ß-monoacylglycerols. Only myristate (C14:0) led to an increase in the biomass of Rhizophagus irregularis, inducing extensive hyphal growth and formation of infection-competent secondary spores. However, such spores were smaller than those generated symbiotically. Furthermore, we demonstrated that R. irregularis can take up fatty acids in its branched hyphae and use myristate as a carbon and energy source. Myristate also promoted the growth of Rhizophagus clarus and Gigaspora margarita Finally, mixtures of myristate and palmitate accelerated fungal growth and induced a substantial change in fatty acid composition of triacylglycerol compared with single myristate application, although palmitate was not used as a carbon source for cell wall biosynthesis in this culture system. Our findings demonstrate that myristate boosts the asymbiotic growth of AM fungi and can also serve as a carbon and energy source.


Assuntos
Glomeromycota/metabolismo , Micorrizas/metabolismo , Miristatos/metabolismo , Carbono/metabolismo , Parede Celular/metabolismo , Metabolismo Energético , Glomeromycota/crescimento & desenvolvimento , Hifas/crescimento & desenvolvimento , Hifas/metabolismo , Micorrizas/crescimento & desenvolvimento
19.
Pak J Biol Sci ; 23(10): 1231-1236, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32981255

RESUMO

Microbes play a vital role in ecosystem stability. Here, microbes-Acacia association is discussed with particular reference to Arbuscular Mycorrhizal Fungi (AMF) which help in the establishment of crop-plants, especially in arid and semi-arid areas. The association helps to restore the structural composition of soil from the hazardous impact of agrochemicals, increase resistance against various pathogenic attack as well as several abiotic stresses. Further, a comparative account of microbes found in the rhizosphere of Acacia is illustrated. Among these, Rhizobia, Acetobacter, Bradyrhizobium, Bacillus, Pseudomonas and Trichoderma were described in detail. All these microbes can be regarded as Plant Growth Promoting Rhizospheric Microbes (PGPM), some of PGPM are Phosphate Solubilizing Microbe (PSM). Both of them help AMF for infecting mycorrhizal hyphae inside the plant cell. Overall, microbes can be used as biofertilizers along with other organic compounds, that can compensate for the nutrient's availability.


Assuntos
Acacia/crescimento & desenvolvimento , Acacia/microbiologia , Ecossistema , Micorrizas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Rizosfera , Microbiologia do Solo , Agricultura/métodos , Biodiversidade , Fertilizantes , Fungos , Nitrogênio , Fósforo , Solo/química , Simbiose
20.
PLoS One ; 15(9): e0237256, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32915795

RESUMO

Arbuscular mycorrhizal fungi (AMF) strongly affect ecosystem functioning. To understand and quantify the mechanisms of this control, knowledge about the relationship between the actual abundance and community composition of AMF in the soil and in plant roots is needed. We collected soil and root samples in a natural dune grassland to test whether, across a plant community, the abundance of AMF in host roots (measured as the total length of roots colonized) is related to soil AMF abundance (using the neutral lipid fatty acids (NLFA) 16:1ω5 as proxy). Next-generation sequencing was used to explore the role of community composition in abundance patterns. We found a strong positive relationship between the total length of roots colonized by AMF and the amount of NLFA 16:1ω5 in the soil. We provide the first field-based evidence of proportional biomass allocation between intra-and extraradical AMF mycelium, at ecosystem level. We suggest that this phenomenon is made possible by compensatory colonization strategies of individual fungal species. Finally, our findings open the possibility of using AMF total root colonization as a proxy for soil AMF abundances, aiding further exploration of the AMF impacts on ecosystems functioning.


Assuntos
Ecossistema , Micorrizas/crescimento & desenvolvimento , Microbiologia do Solo
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