Is cortical root colonization required for carbon transfer to arbuscular mycorrhizal fungi? Evidence from colonization phenotypes and spore production in the reduced mycorrhizal colonization (rmc) mutant of tomato

Botany ◽  
2008 ◽  
Vol 86 (9) ◽  
pp. 1009-1019 ◽  
Author(s):  
Maria Manjarrez ◽  
F. Andrew Smith ◽  
Petra Marschner ◽  
Sally E. Smith
Keyword(s):  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Colonization ◽  
Fungal Mycelium ◽  
Solanum Lycopersicum L ◽  
Carbon Transfer ◽  
External Mycelium ◽  
First Time

For the first time, the phenotypes formed in the reduced mycorrhizal colonization (rmc) Solanum lycopersicum  L. (tomato) mutant with different arbuscular mycorrhizal (AM) fungi were used to explore the potential of different fungal structures to support development of external fungal mycelium and spores. The life cycle of AM fungi with rmc was followed for up to 24 weeks. Results showed that production of external mycelium was slight and transitory for those fungi that did not penetrate the roots of rmc (Pen–) ( Glomus intraradices DAOM181602 and Glomus etunicatum ). For fungi that penetrated the root epidermis and hypodermis (Coi–, Glomus coronatum and Scutellospora calospora ) the mycelium produced varied in size, but was always smaller than with the wild-type 76R. Spores were formed by these fungi with 76R but not with rmc. The only fungus forming a Myc+ phenotype with rmc, G. intraradices WFVAM23, produced as much mycelium with rmc as with 76R. We observed lipid accumulation in hyphae and vesicles in both plant genotypes with this fungus. Mature spores were formed with 76R. However, with rmc, spores remained small and (presumably) immature for up to 24 weeks. We conclude that significant carbon transfer from plant to fungus can occur in Coi– interactions with rmc in which no cortical colonization occurs. We speculate that both carbon transfer and root signals are required for mature spores to be produced.

scholarly journals Growth model for arbuscular mycorrhizal fungi

2007 ◽  
Vol 5 (24) ◽  
pp. 773-784 ◽  
Author(s):  
A Schnepf ◽  
T Roose ◽  
P Schweiger
Keyword(s):  
Mycorrhizal Fungi ◽  
Trifolium Subterraneum ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Fungal Species ◽  
Foraging Strategies ◽  
Fungal Mycelium ◽  
Hyphal Length ◽  
Solute Uptake ◽  
Acaulospora Laevis

In order to quantify the contribution of arbuscular mycorrhizal (AM) fungi to plant phosphorus nutrition, the development and extent of the external fungal mycelium and its nutrient uptake capacity are of particular importance. We develop and analyse a model of the growth of AM fungi associated with plant roots, suitable for describing mechanistically the effects of the fungi on solute uptake by plants. The model describes the development and distribution of the fungal mycelium in soil in terms of the creation and death of hyphae, tip–tip and tip–hypha anastomosis, and the nature of the root–fungus interface. It is calibrated and corroborated using published experimental data for hyphal length densities at different distances away from root surfaces. A good agreement between measured and simulated values was found for three fungal species with different morphologies: Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders; Glomus sp.; and Acaulospora laevis Gerdemann & Trappe associated with Trifolium subterraneum L. The model and findings are expected to contribute to the quantification of the role of AM fungi in plant mineral nutrition and the interpretation of different foraging strategies among fungal species.

Rice phosphate transporters associated with phosphate uptake in rice roots colonised with arbuscular mycorrhizal fungi

2007 ◽  
Vol 85 (7) ◽  
pp. 644-651 ◽  
Author(s):  
Donna Glassop ◽  
Rosamond M. Godwin ◽  
Sally E. Smith ◽  
Frank W. Smith
Keyword(s):  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Rice Genome ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Growth Conditions ◽  
Cortical Cells ◽  
Symbiotic Associations ◽  
Rice Roots ◽  
Pi Acquisition

The completed rice-genome sequence was screened with a known inorganic phosphate (Pi) transporter sequence to reveal a family of 13 Pi transporters. This family can be used for studies into Pi acquisition and translocation throughout the plant. Plants that form symbiotic associations with arbuscular mycorrhizal (AM) fungi are of particular interest with respect to Pi acquisition because of their ability to utilize both direct and fungal pathways of uptake. Localization of transcripts of two Pi transporters by real-time RT-PCR and in situ hybridization were conducted in rice subjected to low Pi, high Pi, and AM colonization. One Pi transporter, ORYsa;Pht1;13, was detected in rice roots under all growth conditions. ORYsa;Pht1;11 was only expressed in roots colonized by AM fungi. Antisense RNA probes of ORYsa;Pht1;11 localized to cortical cells containing arbuscules and hyphal coils, formed by Glomus intraradices Schenck and Smith and Scutellospora calospora (Nicolson and Gerdemann) Walker and Sanders, respectively. Localization of the ORYsa;Pht1;13 probes was similar to that observed for ORYsa;Pht1;11 in colonized rice roots. This research proposes that at least two rice Pi transporters are involved in acquiring Pi via AM fungi, emphasising the complexity of Pi acquisition in plants with access to two Pi uptake pathways.

scholarly journals Fungal Lipid Accumulation and Development of Mycelial Structures by Two Arbuscular Mycorrhizal Fungi

2003 ◽  
Vol 69 (11) ◽  
pp. 6762-6767 ◽  
Author(s):  
Ingrid M. van Aarle ◽  
Pål Axel Olsson
Keyword(s):  
Fatty Acid ◽  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Neutral Lipids ◽  
Phospholipid Fatty Acid ◽  
Plantago Lanceolata ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Fungal Species ◽  
Opposite Pattern

ABSTRACT We monitored the development of intraradical and extraradical mycelia of the arbuscular mycorrhizal (AM) fungi Scutellospora calospora and Glomus intraradices when colonizing Plantago lanceolata. The occurrence of arbuscules (branched hyphal structures) and vesicles (lipid storage organs) was compared with the amounts of signature fatty acids. The fatty acid 16:1ω5 was used as a signature for both AM fungal phospholipids (membrane constituents) and neutral lipids (energy storage) in roots (intraradical mycelium) and in soil (extraradical mycelium). The formation of arbuscules and the accumulation of AM fungal phospholipids in intraradical mycelium followed each other closely in both fungal species. In contrast, the neutral lipids of G. intraradices increased continuously in the intraradical mycelium, while vesicle occurrence decreased after initial rapid root colonization by the fungus. S. calospora does not form vesicles and accumulated more neutral lipids in extraradical than in intraradical mycelium, while the opposite pattern was found for G. intraradices. G. intraradices allocated more of its lipids to storage than did S. calospora. Thus, within a species, the fatty acid 16:1ω5 is a good indicator for AM fungal development. The phospholipid fatty acid 16:1ω5 is especially suitable for indicating the frequency of arbuscules in the symbiosis. We propose that the ratio of neutral lipids to phospholipids is more important than is the presence of vesicles in determining the storage status of AM fungi.

scholarly journals Germinating Spore Exudates from Arbuscular Mycorrhizal Fungi: Molecular and Developmental Responses in Plants and Their Regulation by Ethylene

2011 ◽  
Vol 24 (2) ◽  
pp. 260-270 ◽  
Author(s):  
Arijit Mukherjee ◽  
Jean-Michel Ané
Keyword(s):  
Gene Expression ◽  
Genetic Control ◽  
Root Development ◽  
Mycorrhizal Fungi ◽  
Root Architecture ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Plant Responses ◽  
Symbiotic Gene

Arbuscular mycorrhizal (AM) fungi stimulate root development and induce expression of mycorrhization-specific genes in both eudicots and monocots. Diffusible factors released by AM fungi have been shown to elicit similar responses in Medicago truncatula. Colonization of roots by AM fungi is inhibited by ethylene. We compared the effects of germinating spore exudates (GSE) from Glomus intraradices in monocots and in eudicots, their genetic control, and their regulation by ethylene. GSE modify root architecture and induce symbiotic gene expression in both monocots and eudicots. The genetic regulation of root architecture and gene expression was analyzed using M. truncatula and rice symbiotic mutants. These responses are dependent on the common symbiotic pathway as well as another uncharacterized pathway. Significant differences between monocots and eudicots were observed in the genetic control of plant responses to GSE. However, ethylene inhibits GSE-induced symbiotic gene expression and root development in both groups. Our results indicate that GSE signaling shares similarities and differences in monocots versus eudicots, that only a subset of AM signaling pathways has been co-opted in legumes for the establishment of root nodulation with rhizobia, and that regulation of these pathways by ethylene is a feature conserved across higher land plants.

scholarly journals Mycorrhizal Fungi Enhance Resistance to Herbivores in Tomato Plants with Reduced Jasmonic Acid Production

Agronomy ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 131 ◽  
Author(s):  
Ludovico Formenti ◽  
Sergio Rasmann
Keyword(s):  
Plant Growth ◽  
Jasmonic Acid ◽  
Plant Resistance ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Wild Type ◽  
Tomato Plants ◽  
Solanum Lycopersicum L ◽  
Fungal Inoculation

Arbuscular mycorrhizal (AM) fungi favor plant growth by improving nutrient acquisition, but also by increasing their resistance against abiotic and biotic stressors, including herbivory. Mechanisms of AM fungal mediated increased resistance include a direct effect of AM fungi on plant vigor, but also a manipulation of the hormonal cascades, such as the systemic activation of jasmonic acid (JA) dependent defenses. However, how AM fungal inoculation and variation in the endogenous JA production interact to produce increased resistance against insect herbivores remains to be further elucidated. To address this question, three genotypes of Solanum lycopersicum L., a JA-biosynthesis deficient mutant, a JA over-accumulating mutant, and their wild-type were either inoculated with AM fungi or left un-inoculated. Plant growth-related traits and resistance against Spodoptera littoralis (Boisduval) caterpillars, a major crop pest, were measured. Overall, we found that deficiency in JA production reduced plant development and were the least resistant against S. littoralis. Moreover, AM fungi increased plant resistance against S. littoralis, but such beneficial effect was more pronounced in JA-deficient plant than on JA over-accumulating plants. These results highlight that AM fungi-driven increased plant resistance is negatively affected by the ability of plants to produce JA and that AM fungi complement JA-mediated endogenous plant defenses in this system.

Phosphorus solubilization and pH changes as a result of the interactions between soil bacteria and arbuscular mycorrhizal fungi on a medium containing NH4+as nitrogen source

2001 ◽  
Vol 79 (8) ◽  
pp. 865-870 ◽  
Author(s):  
J Villegas ◽  
J A Fortin
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pseudomonas Putida ◽  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal ◽  
Serratia Plymuthica ◽  
Ph Changes ◽  
Phosphorus Solubilization ◽  
External Mycelium ◽  
Petri Plate

This paper reports the effects of Glomus intraradices (Schenck & Smith) external mycelium, mycorrhizal, and nonmycorrhizal transformed carrot roots (alone or in interaction with Pseudomonas aeruginosa (Schroeter) Migula, Pseudomonas putida (Trevisan) Migula, or Serratia plymuthica (Dyar) Bergey et al.) on phosphorus solubilization and pH changes of the medium. All experiments were conducted in a two-compartment Petri plate system with a NH4+medium containing an insoluble source of phosphorus (P). In interaction with P. aeruginosa, G. intraradices mycorrhizal roots and G. intraradices external mycelium enhanced solubilization of sparingly soluble sources of phosphates above the levels reached with each culture alone. These improvements were correlated with changes in the pH of the media.Key words: Glomus intraradices, P solubilization, external mycelium, Pseudomonas aeruginosa, Pseudomonas putida, Serratia plymuthica.

Microtubules of the mycorrhizal fungus Glomus intraradices in symbiosis with tomato roots

2001 ◽  
Vol 79 (3) ◽  
pp. 307-313 ◽  
Author(s):  
S Timonen ◽  
F A Smith ◽  
S E Smith
Keyword(s):  
Lycopersicon Esculentum ◽  
Filamentous Fungi ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Mycorrhizal Symbiosis ◽  
Tomato Roots ◽  
External Mycelium ◽  
First Time

In this study the presence and orientation of fungal microtubules were recorded in arbuscular mycorrhizal symbiosis for the first time. Visualization of the fungal microtubules was achieved by using a protocol specifically labelling only fungal tubulins. Microtubules of external mycelium, intraradical hyphae, arbuscules, and vesicles of the arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith were examined when in symbiosis with tomato (Lycopersicon esculentum Mill.). Microtubules were organized as bundles in both external and intraradical hyphae. The bundles of microtubules extended directly from intraradical hyphae into the arbuscules, where the microtubules remained as bundles in the larger hyphae. In the fine fungal branches of the arbuscules, microtubules were seen as thinner filaments. Fungal microtubules were seen to connect the intraradical hyphae and arbuscules. In addition, microtubules of adjacent arbuscules could continue directly from one arbuscule to another. Microtubules reached to the basal cone of each vesicle, but the live vesicles, containing many nuclei, seemed devoid of any microtubular labelling.Key words: cytoskeleton, endomycorrhiza, filamentous fungi, tomato, tubulin, Zygomycota.

Relationship between mycorrhizal activity, burning, and plant productivity in tallgrass prairie

1991 ◽  
Vol 69 (12) ◽  
pp. 2597-2602 ◽  
Author(s):  
S. P. Bentivenga ◽  
B. A. D. Hetrick
Keyword(s):  
Plant Growth ◽  
Tallgrass Prairie ◽  
Mycorrhizal Fungi ◽  
Warm Season ◽  
Arbuscular Mycorrhizal ◽  
Mycorrhizal Colonization ◽  
Prairie Grasses ◽  
Vesicular Arbuscular ◽  
The Impact ◽  
First Time

The impact of benomyl fungicide and spring burning on mycorrhizal activity and plant growth was assessed in tallgrass prairie in Kansas. We report for the first time that the productivity of mycotrophic plants can be reduced by inhibition of indigenous vesicular–arbuscular mycorrhizal fungi under field conditions. A vital stain, nitro blue tetrazolium, used to assess active mycorrhizal colonization, proved to be a more sensitive measure of treatment effects than the cell wall stain, trypan blue. Burning stimulated both plant growth and active mycorrhizal colonization. However, by 32 days after burning no differences in colonization were detected. Our observations support the hypothesis that mycorrhizal fungi play an important role in the growth of warm-season tallgrass prairie grasses and may contribute to enhanced plant growth of warm-season tallgrass prairie grasses and may contribute to enchanced plant growth following spring burning. Key words: burning, benomyl fungicide, phosphorus, tallgrass prairie, VA mycorrhizae, warm-season grasses.

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.

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