scholarly journals The model arbuscular mycorrhizal fungus Rhizophagus irregularis harbours endosymbiotic bacteria with a highly reduce genome

2021 ◽  
Author(s):  
Roman Savary ◽  
Frederic G Masclaux ◽  
Ian R Sanders
Keyword(s):  
Mycorrhizal Fungi ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Rhizophagus Irregularis ◽  
Gene Repertoire ◽  
True Nature ◽  
Endosymbiotic Bacteria ◽  
Strong Adaptation ◽  
The Ideal

Arbuscular mycorrhizal fungi (AMF; Glomeromycotina) are symbionts of most plant species that are known to possess unique intracytoplasmic endosymbiotic bacteria with an enigmatic role. Candidatus Moeniiplasma glomeromycotorum (CaMg) was shown to be widespread along the AMF phylogeny and present in most AMF species and isolates of those species. The model AMF species, Rhizophagus irregularis, that can be cultivated in vitro and for which a lot of genomic information now exists, would be the ideal model to study the true nature of the CaMg-AMF symbiosis. However, R. irregularis was never found to host endobacteria. Here we show by DNA sequencing that R. irregularis can, indeed, host CaMg (Ri-CaMg). However, this appears rare as only one R. irregularis isolate out of 58 hosted CaMg. In that isolate, the endosymbiotic bacterial population was genetically homogenous. By sequencing the complete genome of the bacteria, we found that its genome is among the smallest of all known CaMg and Mycoplasma-like genomes, with a highly reduced gene repertoire, suggesting a strong adaptation to the intracellular life. We discuss our findings in the light of previous literature on CaMg and on the same AMF isolates and suggest that these endosymbionts are more likely parasites than non-obligatory mutualists.

scholarly journals The methylome of the model arbuscular mycorrhizal fungus, Rhizophagus irregularis, shares characteristics with early diverging fungi and Dikarya

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Anurag Chaturvedi ◽  
Joaquim Cruz Corella ◽  
Chanz Robbins ◽  
Anita Loha ◽  
Laure Menin ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Plant Species ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Rhizophagus Irregularis ◽  
Functional Differences ◽  
Phosphate Regulation ◽  
Very High

AbstractEarly-diverging fungi (EDF) are distinct from Dikarya and other eukaryotes, exhibiting high N6-methyldeoxyadenine (6mA) contents, rather than 5-methylcytosine (5mC). As plants transitioned to land the EDF sub-phylum, arbuscular mycorrhizal fungi (AMF; Glomeromycotina) evolved a symbiotic lifestyle with 80% of plant species worldwide. Here we show that these fungi exhibit 5mC and 6mA methylation characteristics that jointly set them apart from other fungi. The model AMF, R. irregularis, evolved very high levels of 5mC and greatly reduced levels of 6mA. However, unlike the Dikarya, 6mA in AMF occurs at symmetrical ApT motifs in genes and is associated with their transcription. 6mA is heterogeneously distributed among nuclei in these coenocytic fungi suggesting functional differences among nuclei. While far fewer genes are regulated by 6mA in the AMF genome than in EDF, most strikingly, 6mA methylation has been specifically retained in genes implicated in components of phosphate regulation; the quintessential hallmark defining this globally important symbiosis.

In vitro culture of arbuscular mycorrhizal fungus and Frankia for inoculation of micropropagated Casuarina equisetifolia L.

1999 ◽  
Vol 77 (9) ◽  
pp. 1391-1397
Author(s):  
Genevieve Louise Mark ◽  
John E Hooker ◽  
Alexander Hahn ◽  
Chris T Wheeler
Keyword(s):  
Spore Germination ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Dichlorophenoxyacetic Acid ◽  
Casuarina Equisetifolia ◽  
Half Strength ◽  
2,4 Dichlorophenoxyacetic Acid

Micropropagated, rooted, and calli explants of Casuarina equisetifolia L. were inoculated with Frankia UGL 020605S and the arbuscular mycorrhizal fungus (AMF) Glomus mosseae, in single and dual co-culture, in vitro. Different micropropagation media formulations were evaluated for their capacity to stimulate germination of G. mosseae spores and growth of Frankia. Murashige and Skoog basal nutrient (half strength) medium, supplemented with 6-benzylaminopurine (BAP), 2,4-dichlorophenoxyacetic acid (2,4-D), and pyruvate was selected for the in vitro co-culture of C. equisetifolia callus explants, G. mosseae, and Frankia. This medium (M4) supported 70% AMF spore germination with 44 and 34% of the germinating spores producing single and branched hyphal strands, respectively. Hoaglands (quarter strength, modified by Hoaglands and Arnon (1950)) nutrient medium (M5) with no supplements was selected for the in vitro co-culture of rooted C. equisetifolia explants, G. mosseae, and Frankia and supported 57% AMF spore germination with 29 and 40% of the germinating spores producing single and branched hyphal strands, respectively. Both media supported significant growth of Frankia. In both cases agar was substituted with Terragreen(r). AMF appressoria and intercellular hyphae were observed in rooted C. equisetifolia at 28 days; arbuscule formation occurred at 56 days postinoculation. Frankia infection was evident after 28 days. This was observed in both dual and single in vitro co-cultures. No specific immunofluorescent or immunogold reactions to monoclonal antibodies (mABs) anti-Frankia < 8C5 > and anti-G. mosseae < F5G5 > were evident in C. equisetifolia callus explants.Key words: arbuscular mycorrhizal fungi (AMF), Frankia, Casuarina, micropropagation, immunofluorescent labelling.

scholarly journals Evaluación de un sistema para la micorrización in vitro en plantas de mora de castilla (Rubus glaucus, Benth)

2012 ◽  
Vol 17 (2) ◽  
pp. 140 ◽  
Author(s):  
Urley Adrian Pérez-Moncada ◽  
María Margarita Ramírez-Gómez ◽  
Víctor Manuel Núñez-Zarante ◽  
Marcela Franco-Correa ◽  
Gabriel Roveda-Hoyos
Keyword(s):  
Mycorrhizal Fungi ◽  
Culture System ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Extraradical Mycelium ◽  
Direct Inoculation ◽  
Autotrophic Culture ◽  
Glomus Sp

<strong>Objective</strong>. Obtain an in vitro mycorrhization system in autotrophic culture systems of blackberry plants (Rubus glaucus, Benth). <strong>Materials and methods</strong>. We used spores and root fragments with vesicles of Arbuscular Mycorrhizal Fungus (AMF) Glomus sp (GEV02). We established an autotrophic culture system of blackberry plantlets comparing two methods of direct inoculation of the AMF. We measured the number of spores produced, the length of the extraradical mycelium as well as the percentage of colonization of the AMF. Additionally, we measured the shoot and root length, and the fresh and dry weight of the leaf and root parts to determine the plant development. <strong>Results</strong>. The autotrophic culture system was successful for blackberry plants (Rubus glaucus, Benth; an optimal shoot and root growth was observed. Additionally, we obtained a system that allowed the development of Glomus sp. in in vitro conditions, with the formation of structures typical of the symbiosis as well as a good intraradical colonization, with the production of arbuscules and vesicles, development of extraradical mycelium with branched hyphae, and formation of new spores. <strong>Conclusion</strong>. For the first time, micropropagated blackberry plants associated successfully with an AMF under in vitro conditions, enabling the development of the symbiotic system AMF Glomus sp. associated to roots of micropropagated blackberry plantlets.<br /><strong>Key words</strong>: arbuscular mycorrhizal fungi (AMF), autotrophic culture, Rubus glaucus Benth, Glomus sp. (GEV02), in vitro mycorrhization.

Identification of a Δ11 desaturase from the arbuscular mycorrhizal fungus Rhizophagus irregularis

2020 ◽  
Author(s):  
Henry Cheeld ◽  
Govindprasad Bhutada ◽  
Frederic Beaudoin ◽  
Peter J Eastmond
Keyword(s):  
Fatty Acid ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal Fungus ◽  
Vaccenic Acid ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Fatty Acyl ◽  
Rhizophagus Irregularis ◽  
Fatty Acyl Moiety ◽  
Fatty Acid Species

AbstractArbuscular mycorrhizal fungi are oleaginous organisms and the most abundant fatty acyl moiety usually found in their lipids is palmitvaccenic acid (16:1Δ11cis). However, it is not known how this uncommon fatty acid species is made. Here we have cloned two homologs of Lepidopteran fatty acyl-CoenzymeA Δ11 desaturases from Rhizophagus irregularis. Both DES1 and DES2 are expressed in intraradicle mycelium and can complement the unsaturated fatty acid-requiring auxotrophic growth phenotype of the Saccharomyces cerevisiae ole1Δ mutant. DES1 expression leads almost exclusively to oleic acid (18:1Δ9cis) production, whereas DES2 expression results in the production of 16:1Δ11cis and vaccenic acid (18:1Δ11cis). DES2 therefore encodes a Δ11 desaturase that is likely to be responsible for the synthesis of 16:1Δ11cis in R. irregularis.

scholarly journals Homo- and Dikaryons of the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis Differ in Life History Strategy

2021 ◽  
Vol 12 ◽  
Author(s):  
Edward Umberto Serghi ◽  
Vasilis Kokkoris ◽  
Calvin Cornell ◽  
Jeremy Dettman ◽  
Franck Stefani ◽  
...  
Keyword(s):  
Life History ◽  
Mycorrhizal Fungi ◽  
Life History Traits ◽  
Mycorrhizal Fungus ◽  
Life History Strategy ◽  
Arbuscular Mycorrhizal ◽  
Rhizophagus Irregularis ◽  
Life History Strategies ◽  
Organ Cultures ◽  
Symbiotic Functioning

Arbuscular mycorrhizal fungi (AMF) are obligate plant symbionts that have the potential to improve crop yield. These multinucleate organisms are either “homokaryotic” or “dikaryotic”. In AMF dikaryons, thousands of nuclei originating from two parental strains coexist in the same cytoplasm. In other fungi, homokaryotic and dikaryotic strains show distinct life history traits (LHTs), such as variation in growth rates and fitness. However, how such traits compare between dikaryons and homokaryons of AMF is unknown. To address this, we measured 20 LHT of four dikaryons and five homokaryons of the model fungus Rhizophagus irregularis across root organ cultures of three host plants (carrot, chicory, and tobacco). Our analyses show that dikaryons have clearly distinct life history strategies (LHSs) compared to homokaryons. In particular, spores of homokaryons germinate faster and to a higher proportion than dikaryons, whereas dikaryons grow significantly faster and create a more complex hyphal network irrespective of host plant species. Our study links AMF nuclear status with key LHT with possible implications for mycorrhizal symbiotic functioning.

scholarly journals The Arbuscular Mycorrhizal Fungus Rhizophagus irregularis MUCL 41833 Modulates Metabolites Production of Anchusa officinalis L. Under Semi-Hydroponic Cultivation

2021 ◽  
Vol 12 ◽  
Author(s):  
Annalisa Cartabia ◽  
Evangelia Tsiokanos ◽  
Nikolaos Tsafantakis ◽  
Ismahen Lalaymia ◽  
Aikaterini Termentzi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mycorrhizal Fungi ◽  
High Resolution Mass Spectrometry ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Building Blocks ◽  
Rhizophagus Irregularis ◽  
Cultivation System ◽  
Enhanced Production ◽  
Anchusa Officinalis

Anchusa officinalis is recognized for its therapeutic properties, which are attributed to the production of different metabolites. This plant interacts with various microorganisms, including the root symbiotic arbuscular mycorrhizal fungi (AMF). Whether these fungi play a role in the metabolism of A. officinalis is unknown. In the present study, two independent experiments, associating A. officinalis with the AMF Rhizophagus irregularis MUCL 41833, were conducted in a semi-hydroponic (S-H) cultivation system. The experiments were intended to investigate the primary and secondary metabolites (PMs and SMs, respectively) content of shoots, roots, and exudates of mycorrhized (M) and non-mycorrhized (NM) plants grown 9 (Exp. 1) or 30 (Exp. 2) days in the S-H cultivation system. Differences in the PMs and SMs were evaluated by an untargeted ultrahigh-performance liquid chromatography high-resolution mass spectrometry metabolomics approach combined with multivariate data analysis. Differences in metabolite production were shown in Exp. 1. Volcano-plots analysis revealed a strong upregulation of 10 PMs and 23 SMs. Conversely, in Exp. 2, no significant differences in PMs and SMs were found in shoots or roots between M and NM plants whereas the coumarin scoparone and the furanocoumarin byakangelicin, accumulated in the exudates of the M plants. In Exp. 1, we noticed an enhanced production of PMs, including organic acids and amino acids, with the potential to act as precursors of other amino acids and as building blocks for the production of macromolecules. Similarly, SMs production was significantly affected in Exp 1. In particular, the phenolic compounds derived from the phenylpropanoid pathway. Fifteen di-, tri-, and tetra-meric C6-C3 derivatives of caffeic acid were induced mainly in the roots of M plants, while four oleanane-types saponins were accumulated in the shoots of M plants. Two new salvianolic acid B derivatives and one new rosmarinic acid derivative, all presenting a common substitution pattern (methylation at C-9”' and C-9' and hydroxylation at C-8), were detected in the roots of M plants. The accumulation of diverse compounds observed in colonized plants suggested that AMF have the potential to affect specific plant biosynthetic pathways.

scholarly journals Establishing monoxenic culture of arbuscular mycorrhizal fungus Glomus intraradices through root organ culture

2014 ◽  
Vol 6 (1) ◽  
pp. 290-293 ◽  
Author(s):  
M. Srinivasan ◽  
K. Kumar ◽  
K. Kumutha ◽  
P. Marimuthu
Keyword(s):  
Hairy Root ◽  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Petri Dish ◽  
Monoxenic Culture ◽  
Surface Sterilization ◽  
Traditional System

Arbuscular mycorrhizal fungi are soil fungi distributed worldwide, forming symbiosis with most of the vascular plants for their growth and survival, which is used for sustainable agriculture and ecosystem management. This study investigated the establishment of monoxenic cultures of Glomus intraradices in association with transformed carrot hairy root. The G.intraradices spores were isolated from sugarcane rhizosphere by wet sieving and decanting technique and propagated in open pot culture. Transformation in to carrot hairy root was done using Agrobacterium rhizogenes. Surface sterilization of G.intraradices spores co-cultured with transformed carrot hairy root in Modified Strulla and Romand (MSR) medium was found the host root growth as well as for germination AM spores. After three months of incubation in dark condition, significant production of extensive hyphal growth on MSR medium and an average of 8500-9000 spores per petri dish was observed. The in vitro inoculum exhibited higher potential of root colonization due to numerous intraradices mycelium with extensive spore load. The produced monoxenic inoculum can be used in place of traditional system where it has a advantage of producing contaminant free propagulas. Thus the monoxenic culture system, a powerful tool, of AM sporulation, can be used for the mass production of monoxenic inoculum of AM fungi besides studying its biology.

scholarly journals Investigating unexplained genetic variation and its expression in the arbuscular mycorrhizal fungus Rhizophagus irregularis

2019 ◽  
Author(s):  
Frédéric G. Masclaux ◽  
Tania Wyss ◽  
Marco Pagni ◽  
Pawel Rosikiewicz ◽  
Ian R. Sanders
Keyword(s):  
Genetic Variation ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Rhizophagus Irregularis ◽  
Published Data ◽  
Strong Indication ◽  
Distinct Nucleus

SummaryArbuscular mycorrhizal fungi (AMF) are important symbionts of plants. Recently, studies of the AMF Rhizophagus irregularis recorded within-isolate genetic variation that does not completely match the proposed homokaryon or heterokaryon state (where heterokaryons comprise a population of two distinct nucleus genotypes). We re-analysed published data showing that bi-allelic sites (and their frequencies), detected in proposed homo- and heterokaryote R. irregularis isolates, were similar across independent studies using different techniques. This indicated that observed within-fungus genetic variation was not an artefact of sequencing and that such within-fungus genetic variation possibly exists. We looked to see if bi-allelic transcripts from three R. irregularis isolates matched those observed in the genome as this would give a strong indication of whether bi-allelic sites recorded in the genome were reliable variants. In putative homokaryon isolates, very few bi-allelic transcripts matched those in the genome. In a putative heterokaryon, a large number of bi-allelic transcripts matched those in the genome. Bi-allelic transcripts also occurred in the same frequency in the putative heterokaryon as predicted from allele frequency in the genome. Our results indicate that while within-fungus genome variation in putative homokaryon and heterokaryon AMF was highly similar in 2 independent studies, there was little support that this variation is transcribed in homokaryons. In contrast, within-fungus variation thought to be segregated among two nucleus genotypes in a heterokaryon isolate was indeed transcribed in a way that is proportional to that seen in the genome.

scholarly journals Alkaline extract of the seaweed Ascophyllum nodosum stimulates arbuscular mycorrhizal fungi and their endomycorrhization of plant roots

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sarah Hines ◽  
Timo van der Zwan ◽  
Kevin Shiell ◽  
Katy Shotton ◽  
Balakrishnan Prithiviraj
Keyword(s):  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Ascophyllum Nodosum ◽  
Tube Length ◽  
Direct Stimulation ◽  
Mycorrhizal Associations ◽  
Stimulation Of

AbstractAscophyllum 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.

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