scholarly journals Constitutive overexpression of RAM1 increases arbuscule density during arbuscular mycorrhizal symbiosis in Brachypodium distachyon

2020 ◽  
Author(s):  
Lena M. Müller ◽  
Lidia Campos-Soriano ◽  
Veronique Levesque-Tremblay ◽  
Armando Bravo ◽  
Dierdra A. Daniels ◽  
...  
Keyword(s):  
Brachypodium Distachyon ◽  
Relative Proportion ◽  
Cortical Cell ◽  
Constitutive Expression ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Growth Patterns ◽  
Cortical Cells ◽  
Altered Expression ◽  
Nutrient Exchange

AbstractArbuscular mycorrhizal (AM) symbiosis is a mutually beneficial association of plants and fungi of the sub-phylum Glomeromycotina. The endosymbiotic AM fungi colonize the inner cortical cells of the roots, where they form branched hyphae called arbuscules that function in nutrient exchange with the plant. To support arbuscule development and subsequently bidirectional nutrient exchange, the root cortical cells undergo substantial transcriptional re-programming. REDUCED ARBUSCULAR MYCORRHIZA 1 (RAM1), studied in several dicot plant species, is a major regulator of this cortical cell transcriptional program. Here, we generated ram1 mutants and RAM1 overexpressors in a monocot, Brachypodium distachyon. The AM phenotypes of two ram1 lines revealed that RAM1 is only partly required to enable arbuscule development in B. distachyon. Transgenic lines constitutively overexpressing BdRAM1 showed constitutive expression of AM-inducible genes even in the shoots. Following inoculation with AM fungi, BdRAM1-overexpressing roots showed higher arbuscule densities relative to controls, indicating the potential to manipulate the relative proportion of symbiotic interfaces via modulation of RAM1. However, the overexpressors also show altered expression of hormone biosynthesis genes and aberrant growth patterns including stunted bushy shoots and poor seed set. While these phenotypes possibly provide additional clues about BdRAM1’s scope of influence, they also indicate that directed approaches to increase the density of symbiotic interfaces will require a more focused, potentially cell-type specific manipulation of transcription factor gene expression.

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.

Overexpression of MdIAA24 improves apple drought resistance by positively regulating strigolactone biosynthesis and mycorrhization

2020 ◽  
Author(s):  
Dong Huang ◽  
Qian Wang ◽  
Guangquan Jing ◽  
Mengnan Ma ◽  
Chao Li ◽  
...  
Keyword(s):  
Drought Stress ◽  
Positive Impact ◽  
Growth Parameters ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Land Plant ◽  
Exchange Capacity ◽  
Cortical Cells ◽  
Relative Water ◽  
Am Symbiosis

Abstract Most land plant species have the ability to establish a symbiosis with arbuscular mycorrhizal (AM) fungi. These fungi penetrate into root cortical cells and form branched structures (known as arbuscules) for nutrient exchange. We cloned the MdIAA24 from apple (Malus domestica) following its up-regulation during AM symbiosis. Results demonstrate the positive impact of the overexpression (OE) of MdIAA24 in apple on AM colonization. We observed the strigolactone (SL) synthesis genes, including MdD27, MdCCD7, MdCCD8a, MdCCD8b and MdMAXa, to be up-regulated in the OE lines. Thus, the OE lines exhibited both a higher SL content and colonization rate. Furthermore, we observed that the OE lines were able to maintain better growth parameters under AM inoculation conditions. Under drought stress with the AM inoculation, the OE lines were less damaged, which was demonstrated by a higher relative water content, a lower relative electrolytic leakage, a greater osmotic adjustment, a higher reactive oxygen species scavenging ability, an improved gas exchange capacity and an increased chlorophyll fluorescence performance. Our findings demonstrate that the OE of MdIAA24 in apple positively regulates the synthesis of SL and the formation of arbuscules as a drought stress coping mechanism.

Effects of elevated O3 on microbes in the rhizosphere of mycorrhizal snap bean with different O3 sensitivity

2014 ◽  
Vol 60 (2) ◽  
pp. 93-103 ◽  
Author(s):  
Shuguang Wang ◽  
Fei Wang ◽  
Xiaojun Diao ◽  
Liansheng He
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Biomass ◽  
Microbial Community Structure ◽  
Relative Proportion ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Plant ◽  
Snap Bean ◽  
Elevated Ozone

Elevated ozone (O3) generally affects microbial biomass and community structure in rhizosphere, but these effects are unclear in mycorrhizal plants because arbuscular mycorrhizal (AM) fungi often benefit microbial growth in the rhizosphere. Here, we investigate the effects of elevated O3 on microbial biomass and community structure in the rhizosphere of mycorrhizal snap bean (Phaseolus vulgaris L.) with different O3 sensitivity (R123: O3-tolerant plant; S156: O3-sensitive plant) based on the phospholipid fatty acids (PLFAs) method. Compared with ambient O3, elevated O3 significantly decreased mycorrhizal colonization rates in the 2 genotypes, especially in S156 plants. The wet masses of shoot and root were decreased by elevated O3 in the 2 genotypes independent of AM inoculation, but they were higher in the mycorrhizal plant than in the nonmycorrhizal plant independent of O3 concentration. Elevated O3 significantly decreased the relative proportion of specific fungal PLFAs in the nonmycorrhizal plant, but this effect disappeared in the mycorrhizal plant. The relative proportions of specific PLFAs of other microbial groups (Gram-positive, Gram-negative, and actinomycete) in the rhizosphere and all specific PLFAs in the hyphosphere were not affected by elevated O3 independent of AM inoculation. In the rhizosphere of the 2 genotypes, microbial community structure was changed by AM inoculation and elevated O3 as well as by their interaction; in the hyphosphere, however, microbial community structure was changed by elevated O3 only in R123 plants. It is concluded that AM inoculation can offset negative effect of elevated O3 on fungal biomass but seems to enhance shift of microbial community structure in rhizosphere under elevated O3.

scholarly journals OsRAM2 function in lipid biosynthesis is required for arbuscular mycorrhizal symbiosis in rice

2021 ◽  
Author(s):  
Ying-Na Liu ◽  
Cheng-Chen Liu ◽  
An-Qi Zhu ◽  
Ke-Xin Niu ◽  
Rui Guo ◽  
...  
Keyword(s):  
Expression Patterns ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Root Surface ◽  
Mycorrhizal Symbiosis ◽  
Cortical Cells ◽  
Mutualistic Symbiosis ◽  
Fungal Hyphae ◽  
Mutant Lines

Arbuscular mycorrhiza (AM) is a mutualistic symbiosis formed between most land plants and Glomeromycotina fungi. During the symbiosis, plants provide organic carbon to fungi in exchange for mineral nutrients. Previous legume studies showed that the Required for Arbuscular Mycorrhization2 (RAM2) gene is necessary for transferring lipids from plants to AM fungi (AMF) and is also likely to play a ‘signaling’ role at the root surface. To further explore RAM2 functions in other plant lineages, in this study, two rice (Oryza sativa) genes, OsRAM2 and OsRAM2L, were identified as orthologs of legume RAM2. Examining their expression patterns during symbiosis revealed that only OsRAM2 was strongly upregulated upon AMF inoculation. CRISPR/Cas9 mutagenesis was then performed to obtain three Osram2 mutant lines (-1, -2, and -3). After inoculation by AMF Rhizophagus irregularis or Funneliformis mosseae, all the mutant lines showed extremely low colonization rates and the rarely observed arbuscules were all defective, thus supporting a conserved ‘nutritional’ role of RAM2 between monocot and dicot lineages. As for the ‘signaling’ role, although the hyphopodia numbers formed by both AMF on Osram2 mutants were indeed reduced, their morphology showed no abnormality, with fungal hyphae invading roots successfully. Promoter activities further indicated OsRAM2 was not expressed in epidermal cells below hyphopodia or outer cortical cells enclosing fungal hyphae, but expressed exclusively in cortical cells containing arbuscules. It therefore suggested an indirect role of RAM2 rather than a direct involvement in determining the symbiosis signals at the root surface.

The mycoheterotroph Arachnitis uniflora has a unique association with arbuscular mycorrhizal fungi

Botany ◽  
2009 ◽  
Vol 87 (12) ◽  
pp. 1198-1208 ◽  
Author(s):  
Laura S. Domínguez ◽  
Lewis Melville ◽  
Alicia Sérsic ◽  
Antonella Faccio ◽  
R. Larry Peterson
Keyword(s):  
Host Cell ◽  
Mycorrhizal Fungi ◽  
Cortical Cell ◽  
Arbuscular Mycorrhizal ◽  
Structural Features ◽  
Wall Layer ◽  
Wall Material ◽  
Nutrient Exchange ◽  
Host Cell Wall ◽  
Hyphal Coils

Achlorophyllous plants that are dependent on an association with fungi linked to photosynthetic plants for their carbon source are known as mycoheterotrophs. Arachnitis uniflora Phil., a monotypic member of the monocotyledonous family Corsiaceae, fits this category, as it relies on a glomalean fungus belonging to Glomus Group A for carbon acquisition. Although basic structural features of root colonization have been reported for A. uniflora, the nutrient exchange interface has not been studied. This is the first study to use confocal microscopy, transmission electron microscopy, and cytochemical procedures to study the interface between a glomalean fungus and the roots of a mycoheterotrophic species. Results showed that arbuscules are never formed, and that the “vesicles in bundles” reported earlier are unlike typical glomalean vesicles, in that they form in clusters by the enlargement of hyphal branches and have a complex multilayered wall. The thick inner wall layer consists primarily of β-1,3-glucans (callose) and is surrounded by a thin outer layer of chitin. Each structure is surrounded by host cell wall material and a perifungal membrane, suggesting an involvement in nutrient exchange. The cytoplasm contains a complex of small β-1,3-glucan-containing vacuoles, lipid bodies, endobacteria, and many nuclei. These structures enlarge to occupy most of the cortical cell volume and then degrade, releasing lipids and other materials into the host cell. We suggest that these structures should not be equated with typical glomalean vesicles but are unique structures that may be involved, along with the hyphal coils, in nutrient acquisition by the host.

Genetic supressors of Lotus japonicus har1-1 hypernodulation show altered interactions with Glomus intraradices

2006 ◽  
Vol 33 (8) ◽  
pp. 749 ◽  
Author(s):  
Jeremy Murray ◽  
Ryan Geil ◽  
Cameron Wagg ◽  
Bogumil Karas ◽  
Krzysztof Szczyglowski ◽  
...  
Keyword(s):  
Glomus Intraradices ◽  
Lotus Japonicus ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Parental Line ◽  
Cortical Cells ◽  
Root Colonisation ◽  
Genetic Suppressors ◽  
Am Fungus ◽  
Mutant Lines

Mutant lines of Lotus japonicus (Regel) Larsen that show defects in nodulation as well as in mycorrhiza formation are valuable resources for studying the events required for the establishment of functional symbioses. In this study, 11 mutant lines derived from a screen for genetic suppressors of har1-1 hypernodulation were assessed quantitatively for their ability to form arbuscular mycorrhizal (AM) symbiosis. The presence of extraradical mycelia, appressoria, intraradical hyphae, arbuscules and vesicles were scored. Roots of the har1-1 parental line were heavily colonised by six weeks after inoculation with the AM fungus Glomus intraradices showing the typical Arum-type colonisation pattern. Five mutants lacked internal root colonisation with blocks either at the surface of epidermal cells or at the outer tangential wall of cortical cells. These AM– lines showed some differences in relation to the amount of extraradical hyphae, the number of appressoria, and the degree of abnormal appressorium morphology. Four mutants had internal root colonisation but at a lower level than the parental line. Two mutants showed no difference from the parental line. Results of this study provide additional genetic resources for studying the mechanism of root colonisation by AM fungi.

scholarly journals Sugar transport in arbuscular mycorrhizal symbiosis

2009 ◽  
Vol 89 (2) ◽  
pp. 257-263 ◽  
Author(s):  
S. Sun ◽  
G. Xu
Keyword(s):  
Plasma Membrane ◽  
Sugar Transport ◽  
Cortical Cell ◽  
Arbuscular Mycorrhizal ◽  
Arbuscular Mycorrhizal Symbiosis ◽  
Mycorrhizal Symbiosis ◽  
Sugar Transporters ◽  
Nutrient Exchange ◽  
Am Symbiosis ◽  
Cell Interface

In arbuscular mycorrhizal (AM) symbioses, there is a reciprocal nutrient exchange, mainly sugar and phosphate, between partners. Transport of phosphate from fungus to plant has been well characterized, and this aspect of AM symbiosis has been reviewed. This mini-review is specifically devoted to sugar transport from plant to fungus in AM symbiosis and discusses the possible links between sugar transporters and AM-inducible inorganic phosphate (Pi) transporters and plasma membrane proton-ATPases in the arbuscule-cortical cell interface. Exploring the sugar transport mechanisms could further contribute to our understanding of nutrient exchange between the two symbiotic partners. Key words: Arbuscular mycorrhizal symbiosis, sugar flux, sugar transporter, phosphate transporter, plasma membrane, H+-ATPase

scholarly journals Colonization of mutualistic mycorrhizal and parasitic blast fungi requires OsRAM2-regulated fatty acid biosynthesis in rice

2021 ◽  
Author(s):  
Ertao Wang ◽  
Huiling Dai ◽  
Xiaowei Zhang ◽  
Boyu Zhao ◽  
Jincai Shi ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Pathogenic Fungi ◽  
Land Plants ◽  
Lipid Transport ◽  
Acid Biosynthesis ◽  
Cortical Cells ◽  
Mutualistic Fungi

Arbuscular mycorrhizal (AM) fungi form a mutual association with the majority of land plants, including most angiosperms of the dicotyledon and monocotyledon lineages. The symbiosis is based upon bidirectional nutrient exchange between the host and symbiont that occurs between inner cortical cells of the root and branched AM hyphae called arbuscules that develop within these cells. Lipid transport and its regulation during the symbiosis have been intensively investigated in dicotyledon plants, especially legumes. Here, we characterize OsRAM2 and OsRAM2L, homologs of M. truncatula RAM2, and found that plants defective in OsRAM2 were unable to be colonized by AM fungi and showed impaired colonization by Magnaporthe oryzae. The induction of OsRAM2 and OsRAM2L is dependent on OsRAM1 and the CSSP pathway genes CCaMK and CYCLOPS, while overexpression of OsRAM1 results in increased expression of OsRAM2 and OsRAM2L. Collectively, our data show that the function and regulation of OsRAM2 is conserved in monocot and dicot plants and reveals that, similar to mutualistic fungi, pathogenic fungi have recruited RAM2-mediated fatty acid biosynthesis to facilitate invasion.

scholarly journals Resource allocation to growth or luxury consumption drives mycorrhizal responses

2019 ◽  
Author(s):  
Rohan Riley ◽  
Timothy Cavagnaro ◽  
Chris Brien ◽  
F. Andrew Smith ◽  
Sally Smith ◽  
...  
Keyword(s):  
Resource Allocation ◽  
Brachypodium Distachyon ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Host Genotype ◽  
Luxury Consumption ◽  
Non Invasive ◽  
P Limitation ◽  
Functional Understanding ◽  
High Throughput Phenotyping

Highly variable phenotypic responses in mycorrhizal plants challenge our functional understanding of plant-fungal mutualisms. Using non-invasive high-throughput phenotyping, we observed that arbuscular mycorrhizal (AM) fungi relieved phosphorus (P) limitation and enhanced growth of Brachypodium distachyon under P-limited conditions, while photosynthetic limitation under low nitrogen (N) was exacerbated by the fungus. However, these responses were strongly dependent on host genotype: only the faster growing genotype (Bd3-1) utilised P transferred from the fungus to achieve improved growth under P-limited conditions. Under low N, the slower growing genotype (Bd21) had a carbon and N surplus that was linked to a less negative growth response compared with the faster growing genotype. These responses were linked to the regulation of N:P stoichiometry, couples resource allocation to growth or luxury consumption in diverse plant lineages. Our results attest strongly to a mechanism in plants by which plant genotype-specific resource economics drive phenotypic outcomes during AM symbioses.

scholarly journals Tracking of Zinc Ferrite Nanoparticle Effects on Pea (Pisum sativum L.) Plant Growth, Pigments, Mineral Content and Arbuscular Mycorrhizal Colonization

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 583
Author(s):  
Reda E. Abdelhameed ◽  
Nagwa I. Abu-Elsaad ◽  
Arafat Abdel Hamed Abdel Latef ◽  
Rabab A. Metwally
Keyword(s):  
Pisum Sativum ◽  
Plant Growth ◽  
Zinc Ferrite ◽  
Crop Improvement ◽  
Nanocrystalline Structure ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Transmission Electron ◽  
Agricultural Applications ◽  
The Impact

Important gaps in knowledge remain regarding the potential of nanoparticles (NPs) for plants, particularly the existence of helpful microorganisms, for instance, arbuscular mycorrhizal (AM) fungi present in the soil. Hence, more profound studies are required to distinguish the impact of NPs on plant growth inoculated with AM fungi and their role in NP uptake to develop smart nanotechnology implementations in crop improvement. Zinc ferrite (ZnFe2O4) NPs are prepared via the citrate technique and defined by X-ray diffraction (XRD) as well as transmission electron microscopy for several physical properties. The analysis of the XRD pattern confirmed the creation of a nanocrystalline structure with a crystallite size equal to 25.4 nm. The effects of ZnFe2O4 NP on AM fungi, growth and pigment content as well as nutrient uptake of pea (Pisum sativum) plants were assessed. ZnFe2O4 NP application caused a slight decrease in root colonization. However, its application showed an augmentation of 74.36% and 91.89% in AM pea plant shoots and roots’ fresh weights, respectively, compared to the control. Moreover, the synthesized ZnFe2O4 NP uptake by plant roots and their contents were enhanced by AM fungi. These findings suggest the safe use of ZnFe2O4 NPs in nano-agricultural applications for plant development with AM fungi.

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