scholarly journals The Pre-Symbiotic Growth of Arbuscular Mycorrhizal Fungi Is Induced by a Branching Factor Partially Purified from Plant Root Exudates

2000 ◽  
Vol 13 (6) ◽  
pp. 693-698 ◽  
Author(s):  
M. Buee ◽  
M. Rossignol ◽  
A. Jauneau ◽  
R. Ranjeva ◽  
G. Bécard
Keyword(s):  
Plant Species ◽  
Root Exudates ◽  
Mycorrhizal Fungi ◽  
Plant Root ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Flavonoid Pathway ◽  
Highly Active ◽  
Nonhost Plant

Arbuscular mycorrhizal (AM) symbiosis is an association between obligate biotrophic fungi and more than 80% of land plants. During the pre-symbiotic phase, the host plant releases critical metabolites necessary to trigger fungal growth and root colonization. We describe the isolation of a semipurified fraction from exudates of carrot hairy roots, highly active on germinating spores of Gigaspora gigantea, G. rosea, and G. margarita. This fraction, isolated on the basis of its activity on hyphal branching, contains a root factor (one or several molecules) that stimulates, directly or indirectly, G. gigantea nuclear division. We demonstrate the presence of this active factor in root exudates of all mycotrophic plant species tested (eight species) but not in those of nonhost plant species (four species). We negatively tested the hypothesis that it was a flavonoid or a compound synthesized via the flavonoid pathway. We propose that this root factor, yet to be chemically characterized, is a key plant signal for the development of AM fungi.

scholarly journals Use of the Signature Fatty Acid 16:1ω5 as a Tool to Determine the Distribution of Arbuscular Mycorrhizal Fungi in Soil

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Christopher Ngosong ◽  
Elke Gabriel ◽  
Liliane Ruess
Keyword(s):  
Fatty Acid ◽  
Mycorrhizal Fungi ◽  
Plant Root ◽  
Background Level ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Biomass Estimation ◽  
Lipid Fatty Acid ◽  
Neutral Lipid Fatty Acid ◽  
Root Symbionts

Biomass estimation of arbuscular mycorrhiza (AM) fungi, widespread plant root symbionts, commonly employs lipid biomarkers, predominantly the fatty acid 16:1ω5. We briefly reviewed the application of this signature fatty acid, followed by a case study comparing biochemical markers with microscopic techniques in an arable soil following a change to AM non-host plants after 27 years of continuous host crops, that is, two successive cropping seasons with wheat followed by amaranth. After switching to the non-host amaranth, spore biomass estimated by the neutral lipid fatty acid (NLFA) 16:1ω5 decreased to almost nil, whereas microscopic spore counts decreased by about 50% only. In contrast, AM hyphal biomass assessed by the phospholipid (PLFA) 16:1ω5 was greater under amaranth than wheat. The application of PLFA 16:1ω5 as biomarker was hampered by background level derived from bacteria, and further enhanced by its incorporation from degrading spores used as microbial resource. Meanwhile, biochemical and morphological assessments showed negative correlation for spores and none for hyphal biomass. In conclusion, the NLFA 16:1ω5 appears to be a feasible indicator for AM fungi of the Glomales group in the complex field soils, whereas the use of PLFA 16:1ω5 for hyphae is unsuitable and should be restricted to controlled laboratory studies.

Root-colonizing and soil-borne communities of arbuscular mycorrhizal fungi in a temperate forest understorey

Botany ◽  
2014 ◽  
Vol 92 (4) ◽  
pp. 277-285 ◽  
Author(s):  
Ülle Saks ◽  
John Davison ◽  
Maarja Öpik ◽  
Martti Vasar ◽  
Mari Moora ◽  
...  
Keyword(s):  
Plant Species ◽  
Mycorrhizal Fungi ◽  
Plant Root ◽  
Arbuscular Mycorrhizal ◽  
Small Subunit ◽  
Plant Roots ◽  
Individual Plant ◽  
Amf Communities ◽  
Arbuscular Mycorrhizal Fungal ◽  
Phylogenetic Dispersion

We analyzed arbuscular mycorrhizal fungal (AMF) communities in plant root samples from a natural forest ecosystem — a primeval forest in Järvselja, Estonia. AMF small-subunit (SSU) ribosomal RNA genes were subjected to 454-pyrosequencing and BLAST-based taxonomic identification. Seventy-six AMF sequence groups (virtual taxa, VT) were identified from plant roots. Taken together with seven additional VT recorded in an earlier investigation of soil AMF communities at the site, this represents the highest number of AMF reported from a single ecosystem to date. The six study plant species hosted similar AMF communities. However, AMF community composition in plant roots was significantly different from that in soil and considerably more VT were retrieved from roots than from soil. AMF VT identified from plant roots as a whole and from individual plant species were frequently phylogenetically clustered compared with local and global taxon pools, suggesting that nonrandom assembly processes, notably habitat filtering, may have shaped fungal assemblages. In contrast, the phylogenetic dispersion of AMF communities in soil did not differ from random subsets of the local or global taxon pools.

scholarly journals 406 Plant Diversity Influences Effectiveness of Associated Arbuscular–Mycorrhizal Fungi

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 463A-463
Author(s):  
Rhoda Burrows ◽  
Francis Pfleger
Keyword(s):  
Plant Species ◽  
Plant Diversity ◽  
Fungal Community ◽  
Mycorrhizal Fungi ◽  
Fungal Spores ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Schizachyrium Scoparium ◽  
Plant Host ◽  
Little Bluestem

Growing a plant host in association with other plant species (i.e., increasing diversity) changes the composition of the associated arbuscular–mycorrhizal (AM) fungal community. We tested whether this alteration in the fungal community causes significant differences in the growth of Schizachyrium scoparium L. (Little Bluestem, a C4 grass) or Lespedeza capitata L. (Bush clover, a legume). Seedlings were transplanted into pasteurized soil inoculated with soil from monoculture plots of Schizachyrium or Lespedeza, respectively, vs. plots containing one, seven, or 15 additional plant species. Soil washes from a composite of the plots were added to all pots, including non-inoculated controls, to reduce differences in the non-AM microbial communities. Spore counts of the inoculum from Lespedeza plots showed increasing numbers of AM fungal spores and species richness with increasing plant diversity; this was not true with the Schizachyrium plots, possibly because Schizachyrium may be a better host to more species of AM fungi than Lespedeza. Both Schizachyrium and Lespedeza responded to inoculation with increased growth compared to non-inoculated controls. Tissue analyses of both species showed that inoculation increased the percentage of Cu, and lowered the percentage of Mn compared to control plants. Schizachyrium showed no significant differences in growth due to inoculum source (1-, 2-, 8-, or 16-species plots); while Lespedeza showed increases in root and shoot weights with increasing source-plot diversity.

scholarly journals Myristate can be used as a carbon and energy source for the asymbiotic growth of arbuscular mycorrhizal fungi

2019 ◽  
Author(s):  
Yuta Sugiura ◽  
Rei Akiyama ◽  
Sachiko Tanaka ◽  
Koji Yano ◽  
Hiromu Kameoka ◽  
...  
Keyword(s):  
Energy Source ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Mycorrhizal Fungi ◽  
Unsaturated Fatty Acids ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Land Plants ◽  
Symbiotic Associations

AbstractArbuscular mycorrhizal (AM) fungi, forming symbiotic associations with land plants, are obligate symbionts that cannot complete their natural life cycle without a host. Recently, fatty acid auxotrophy of AM fungi is supported by 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 (1-7). 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–C18) and two β-monoacylglycerols. Only myristate (C14:0) led to an increase in 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. In conclusion, here we demonstrate that myristate boosts asymbiotic growth of AM fungi and can also serve as a carbon and energy source.Significance statementThe origins of arbuscular mycorrhizal (AM) fungi, which form symbiotic associations with land plants, date back over 460 million years ago. During evolution, these fungi acquired an obligate symbiotic lifestyle, and thus depend on their host for essential nutrients. In particular, fatty acids are regarded as crucial nutrients for the survival of AM fungi owing to the absence of genes involved in de novo fatty acid biosynthesis in the AM fungal genomes that have been sequenced so far. Here, we show that myristate initiates AM fungal growth under asymbiotic conditions. These findings will advance pure culture of AM fungi.

scholarly journals Arbuscular mycorrhizal fungi increase Pb uptake of colonized and non-colonized Medicago truncatula root and deliver extra Pb to colonized root

2021 ◽  
Author(s):  
Haoqiang Zhang ◽  
Wei Ren ◽  
Yaru Zheng ◽  
Fei Zhao ◽  
Ming Tang
Keyword(s):  
Medicago Truncatula ◽  
Mycorrhizal Fungi ◽  
Plant Root ◽  
Biomass Accumulation ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Shoot Biomass ◽  
Terrestrial Plants ◽  
Split Root ◽  
Split Root System

Abstract Aims Arbuscular mycorrhizal (AM) fungi form symbiosis with terrestrial plants and improve lead (Pb) tolerance of host plants. The AM plants accumulate more Pb in root than their non-mycorrhizal counterparts. However, the direct contribution of the mycorrhizal pathway to host plant Pb uptake was less reported. Methods In this study, the AM fungi colonized and non-colonized root of Medicago truncatula was separated by a split-root system, and their differences in responding to Pb application was compared. Results Inoculation of Rhizophagus irregularis increased shoot biomass accumulation and transpiration, and decreased both colonized and non-colonized root biomass accumulation. Application of Pb in the non-colonized root compartment increased the colonization rate of R. irregularis and up-regulated the relative expressions of MtPT4 and MtBCP1 in the colonized root compartment. Inoculation of R. irregularis increased the Pb uptake in both colonized and non-colonized plant root, while R. irregularis transferred Pb to the colonized root. The Pb transferred through the mycorrhizal pathway had low mobility move from root to shoot, and might be sequestrated and compartmented by R. irregularis. Conclusions The Pb uptake of plant root might follow water flow that facilitated by the aquaporin MtPIP2. The quantification of Pb transfer via mycorrhizal pathway and the involvement of MtPIP2 deserve further study.

scholarly journals Tillage, Glyphosate and Beneficial Arbuscular Mycorrhizal Fungi: Optimising Crop Management for Plant–Fungal Symbiosis

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 520 ◽  
Author(s):  
Thomas I. Wilkes ◽  
Douglas J. Warner ◽  
Keith G. Davies ◽  
Veronica Edmonds-Brown
Keyword(s):  
Mycorrhizal Fungi ◽  
Fungal Biomass ◽  
Negative Impact ◽  
Cropping Systems ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Soil Microbiome ◽  
Epsp Synthase ◽  
The Impact

Zero till cropping systems typically apply broad-spectrum herbicides such as glyphosate as an alternative weed control strategy to the physical inversion of the soil provided by cultivation. Glyphosate targets 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase in plants. There is growing evidence that this may have a detrimental impact on non-target organisms such as those present in the soil microbiome. Species of commercial importance, such as arbuscular mycorrhizal (AM) fungi that form a symbiotic relationship with plant roots are an important example. This study investigates the impact of soil cultivation and glyphosate application associated with conventional tillage (CT) and zero tillage (ZT) respectively on AM fungi populations under field and glasshouse conditions. Topsoil (<10 cm) was extracted from CT and ZT fields cropped with winter wheat, plus non-cropped control plots within the same field boundary, throughout the cropping year. Glyphosate was applied in glasshouse experiments at rates between 0 and 350 g L−1. Ergosterol, an indicator of fungal biomass, was measured using high performance liquid chromatography before and after glyphosate application. Fungal root arbuscules, an indicator of AM fungi–root symbiosis, were quantified from the roots of wheat plants. Under glasshouse conditions root arbuscules were consistently higher in wheat grown in ZT field extracted soils (P = 0.01) compared to CT. Glyphosate application however inhibited fungal biomass in both the ZT (P < 0.00001) and CT (P < 0.001) treatments. In the absence of glyphosate, the number of stained root arbuscules increased significantly. Ergosterol levels, used as a proxy for fungal biomass, remained lower in the soil post glyphosate application. The results suggest that CT has a greater negative impact on AM fungal growth than ZT and glyphosate, but that glyphosate is also detrimental to AM fungal growth and hinders subsequent population recovery.

scholarly journals Artificial intelligence enables the identification and quantification of arbuscular mycorrhizal fungi in plant roots

2021 ◽  
Author(s):  
Edouard Evangelisti ◽  
Carl Turner ◽  
Alice McDowell ◽  
Liron Shenhav ◽  
Temur Yunusov ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Plant Root ◽  
Lotus Japonicus ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Root Systems ◽  
Experimental Conditions ◽  
Root Colonisation ◽  
Fungal Colonisation ◽  
Identification And Quantification

Soil fungi establish mutualistic interactions with the roots of most vascular land plants. Arbuscular mycorrhizal (AM) fungi are among the most extensively characterised mycobionts to date. Current approaches to quantifying the extent of root colonisation and the relative abundance of intraradical hyphal structures in mutant roots rely on staining and human scoring involving simple, yet repetitive tasks prone to variations between experimenters. We developed the software AMFinder which allows for automatic computer vision-based identification and quantification of AM fungal colonisation and intraradical hyphal structures on ink-stained root images using convolutional neural networks. AMFinder delivered high-confidence predictions on image datasets of colonised roots of Medicago truncatula, Lotus japonicus, Oryza sativa and Nicotiana benthamiana obtained via flatbed scanning or digital microscopy enabling reproducible and transparent data analysis. A streamlined protocol for sample preparation and imaging allowed us to quantify dynamic increases in colonisation in whole root systems over time. AMFinder adapts to a wide array of experimental conditions. It enables accurate, reproducible analyses of plant root systems and will support better documentation of AM fungal colonisation analyses. AMFinder can be accessed here: https://github.com/SchornacklabSLCU/amfinder.git

Strigolactones seem not to be involved in the nonsusceptibilty of arbuscular mycorrhizal (AM) nonhost plants to AM fungi

Botany ◽  
2011 ◽  
Vol 89 (4) ◽  
pp. 285-288 ◽  
Author(s):  
Antonio Illana ◽  
José M. García-Garrido ◽  
Inmaculada Sampedro ◽  
Juan A. Ocampo ◽  
Horst Vierheilig
Keyword(s):  
Mycorrhizal Fungi ◽  
Host Plants ◽  
Glomus Intraradices ◽  
Experimental System ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Wild Type ◽  
Nonhost Plant ◽  
Plant Families ◽  
Pea Mutant

Although most land plants are hosts for arbuscular mycorrhizal fungi (AMF), a small number of plant families are arbuscular mycorrhizal (AM) nonhosts. There are indications that strigolactone levels in root exudates of AM nonhost plants are lower than in AM host plants, and it has been shown that in the strigolactone-deficient rms1 mutant (ccd8) of the AM host plant pea, the AMF colonization of roots is highly reduced. Application of the synthetic strigolactone analogue GR24 to this strigolactones-deficient mutant restored AMF colonization of roots. Our objective was to determine whether the application of GR24 to AM nonhost plants can affect their susceptibility to AMF. To test whether GR24 affects AMF colonization in our experimental system, we added GR24 to the strigolactone-deficient pea ccd8 mutant. Application of GR24 increased AMF colonization in the pea mutant to a similar level as in the pea wild type with normal strigolactone levels, showing clearly that in our experimental setup, application of the GR24 positively affects AMF colonization in strigolactone-deficient plants. Observation of cleared roots after application of GR24 to four AM nonhost plant species inoculated with the AMF Glomus intraradices showed that colonization did not occur.

scholarly journals Myristate can be used as a carbon and energy source for the asymbiotic growth of arbuscular mycorrhizal fungi

2020 ◽  
Vol 117 (41) ◽  
pp. 25779-25788
Author(s):  
Yuta Sugiura ◽  
Rei Akiyama ◽  
Sachiko Tanaka ◽  
Koji Yano ◽  
Hiromu Kameoka ◽  
...  
Keyword(s):  
Energy Source ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Mycorrhizal Fungi ◽  
Unsaturated Fatty Acids ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Hyphal Growth ◽  
Symbiotic Associations

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 β-monoacylglycerols. Only myristate (C14:0) led to an increase in the biomass ofRhizophagus irregularis, inducing extensive hyphal growth and formation of infection-competent secondary spores. However, such spores were smaller than those generated symbiotically. Furthermore, we demonstrated thatR. irregulariscan take up fatty acids in its branched hyphae and use myristate as a carbon and energy source. Myristate also promoted the growth ofRhizophagus clarusandGigaspora 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.

Sign in / Sign up

Export Citation Format

Share Document