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 Expression Analysis of the First Arbuscular Mycorrhizal Fungi Aquaporin Described Reveals Concerted Gene Expression Between Salt-Stressed and Nonstressed Mycelium

2009 ◽  
Vol 22 (9) ◽  
pp. 1169-1178 ◽  
Author(s):  
Ricardo Aroca ◽  
Alberto Bago ◽  
Moira Sutka ◽  
José Antonio Paz ◽  
Custodia Cano ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Water Channel ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Beneficial Effects ◽  
Host Root ◽  
Soil Water Resources

Roots of most plants in nature are colonized by arbuscular mycorrhizal (AM) fungi. Among the beneficial effects of this symbiosis to the host plant is the transport of water by the AM mycelium from inaccessible soil water resources to host roots. Here, an aquaporin (water channel) gene from an AM fungus (Glomus intraradices), which was named GintAQP1, is reported for the first time. From experiments in different colonized host roots growing under several environmental conditions, it seems that GintAQP1 gene expression is regulated in a compensatory way regarding host root aquaporin expression. At the same time, from in vitro experiments, it was shown that a signaling communication between NaCl-treated mycelium and untreated mycelium took place in order to regulate gene expression of both GintAQP1 and host root aquaporins. This communication could be involved in the transport of water from osmotically favorable growing mycelium or host roots to salt-stressed tissues.

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.

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 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 A role for the mevalonate pathway in early plant symbiotic signaling

2015 ◽  
Vol 112 (31) ◽  
pp. 9781-9786 ◽  
Author(s):  
Muthusubramanian Venkateshwaran ◽  
Dhileepkumar Jayaraman ◽  
Mireille Chabaud ◽  
Andrea Genre ◽  
Allison J. Balloon ◽  
...  
Keyword(s):  
Gene Expression ◽  
Plasma Membrane ◽  
Mycorrhizal Fungi ◽  
Mevalonate Pathway ◽  
Arbuscular Mycorrhizal ◽  
Cation Channel ◽  
Symbiotic Gene ◽  
Heterologous System ◽  
Key Enzyme ◽  
Coa Reductase

Rhizobia and arbuscular mycorrhizal fungi produce signals that are perceived by host legume receptors at the plasma membrane and trigger sustained oscillations of the nuclear and perinuclear Ca2+ concentration (Ca2+ spiking), which in turn leads to gene expression and downstream symbiotic responses. The activation of Ca2+ spiking requires the plasma membrane-localized receptor-like kinase Does not Make Infections 2 (DMI2) as well as the nuclear cation channel DMI1. A key enzyme regulating the mevalonate (MVA) pathway, 3-Hydroxy-3-Methylglutaryl CoA Reductase 1 (HMGR1), interacts with DMI2 and is required for the legume–rhizobium symbiosis. Here, we show that HMGR1 is required to initiate Ca2+ spiking and symbiotic gene expression in Medicago truncatula roots in response to rhizobial and arbuscular mycorrhizal fungal signals. Furthermore, MVA, the direct product of HMGR1 activity, is sufficient to induce nuclear-associated Ca2+ spiking and symbiotic gene expression in both wild-type plants and dmi2 mutants, but interestingly not in dmi1 mutants. Finally, MVA induced Ca2+ spiking in Human Embryonic Kidney 293 cells expressing DMI1. This demonstrates that the nuclear cation channel DMI1 is sufficient to support MVA-induced Ca2+ spiking in this heterologous system.

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 A Phosphate-Dependent Requirement for Transcription Factors IPD3 and IPD3L During Arbuscular Mycorrhizal Symbiosis in Medicago truncatula

2019 ◽  
Vol 32 (10) ◽  
pp. 1277-1290
Author(s):  
Penelope L. Lindsay ◽  
Brandon N. Williams ◽  
Allyson MacLean ◽  
Maria J. Harrison
Keyword(s):  
Gene Expression ◽  
Signaling Pathway ◽  
Medicago Truncatula ◽  
Lotus Japonicus ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Symbiosis ◽  
Wild Type ◽  
Symbiotic Gene ◽  
Am Symbiosis

During arbuscular mycorrhizal (AM) symbiosis, activation of a symbiosis signaling pathway induces gene expression necessary for accommodation of AM fungi. Here, we focus on pathway components Medicago truncatula INTERACTING PROTEIN OF DOES NOT MAKE INFECTIONS 3 (IPD3) and IPD3 LIKE (IPD3L), which are potential orthologs of Lotus japonicus CYCLOPS, a transcriptional regulator essential for AM symbiosis. In the double mutant ipd3 ipd3l, hyphal entry through the epidermis and overall colonization levels are reduced relative to the wild type but fully developed arbuscules are present in the cortex. In comparison with the wild type, colonization of ipd3 ipd3l is acutely sensitive to higher phosphate levels in the growth medium, with a disproportionate decrease in epidermal penetration, overall colonization, and symbiotic gene expression. When constitutively expressed in ipd3 ipd3l, an autoactive DOES NOT MAKE INFECTIONS 3 induces the expression of transcriptional regulators REDUCED ARBUSCULAR MYCORRHIZA 1 and REQUIRED for ARBUSCULE DEVELOPMENT 1, providing a possible avenue for arbuscule development in the absence of IPD3 and IPD3L. An increased sensitivity of ipd3 ipd3l to GA3 suggests an involvement of DELLA. The data reveal partial redundancy in the symbiosis signaling pathway, which may ensure robust signaling in low-phosphorus environments, while IPD3 and IPD3L maintain signaling in higher-phosphorus environments. The latter may buffer the pathway from short-term variation in phosphorus levels encountered by roots during growth in heterogeneous soil environments.

Effects of external phosphate concentration on glucose-6-phosphate dehydrogenase gene expression in the arbuscular mycorrhizal fungus Glomus intraradices

2006 ◽  
Vol 52 (9) ◽  
pp. 823-830 ◽  
Author(s):  
L I Stewart ◽  
S Jabaji-Hare ◽  
B T Driscoll
Keyword(s):  
Gene Expression ◽  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Pentose Phosphate ◽  
Dehydrogenase Gene ◽  
Significant Difference ◽  
Glucose 6 Phosphate Dehydrogenase

Specific primers were developed to amplify a 227 bp segment of the arbuscular mycorrhizal fungus Glomus intraradices gene encoding glucose-6-phosphate dehydrogenase (G6PDH), an enzyme involved in the pentose phosphate pathway. G6PDH gene expression was measured by real-time quantitative reverse transcriptase – polymerase chain reaction in response to phosphorus (P) concentrations in the growth medium of colonized transformed carrot roots. We investigated the effects of different P concentration treatments on carbon (C) metabolism within the intraradical mycelia of G. intraradices. The results showed a significant (P = 0.017) down-regulation of G6PDH expression in the intraradical mycelia of G. intraradices cultures grown in high P than low P conditions but no significant difference in regulation in excessive P concentrations when compared with the low P or high P concentrations. These results indicate that a reduction in the C flow from the host could be occurring as a result of elevated P and that a decrease in fungal G6PDH gene expression occurs, but not in the short term (less than 2 h). Reduced C flow from the host could lead to reduced fungal growth and root colonization, as was observed under high soil P conditions.Key words: arbuscular mycorrhizal fungi, phosphorus, nutrient uptake, glucose-6-phosphate dehydrogenase, gene expression.

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