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.

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 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

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.

scholarly journals Genetic Suppressors of the Lotus japonicus har1-1 Hypernodulation Phenotype

2006 ◽  
Vol 19 (10) ◽  
pp. 1082-1091 ◽  
Author(s):  
Jeremy Murray ◽  
Bogumil Karas ◽  
Loretta Ross ◽  
Andreas Brachmann ◽  
Cameron Wagg ◽  
...  
Keyword(s):  
Glomus Intraradices ◽  
Lotus Japonicus ◽  
Introgression Line ◽  
Nodule Development ◽  
Genetic Dissection ◽  
Kinase Gene ◽  
Mesorhizobium Loti ◽  
Genetic Suppressors ◽  
Nodulation Capacity ◽  
Mutant Lines

Lotus japonicus har1 mutants respond to inoculation with Mesorhizobium loti by forming an excessive number of nodules due to genetic lesions in the HAR1 autoregulatory receptor kinase gene. In order to expand the repertoire of mutants available for the genetic dissection of the root nodule symbiosis (RNS), a screen for suppressors of the L. japonicus har1-1 hypernodulation phenotype was performed. Of 150,000 M2 plants analyzed, 61 stable L. japonicus double-mutant lines were isolated. In the context of the har1-1 mutation, 26 mutant lines were unable to form RNS, whereas the remaining 35 mutant lines carried more subtle symbiotic phenotypes, either forming white ineffective nodules or showing reduced nodulation capacity. When challenged with Glomus intraradices, 18 of the 61 suppressor lines were unable to establish a symbiosis with this arbuscular mycorrhiza fungus. Using a combined approach of genetic mapping, targeting induced local lesions in genomics, and sequencing, all non-nodulating mutant lines were characterized and shown to represent new alleles of at least nine independent symbiotic loci. The class of mutants with reduced nodulation capacity was of particular interest because some of them may specify novel plant functions that regulate nodule development in L. japonicus. To facilitate mapping of the latter class of mutants, an introgression line, in which the har1-1 allele was introduced into a polymorphic background of L. japonicus ecotype MG20, was constructed.

scholarly journals The Lotus japonicus LjSym4 Gene Is Required for the Successful Symbiotic Infection of Root Epidermal Cells

2000 ◽  
Vol 13 (10) ◽  
pp. 1109-1120 ◽  
Author(s):  
Paola Bonfante ◽  
Andrea Genre ◽  
Antonella Faccio ◽  
Isabella Martini ◽  
Leif Schauser ◽  
...  
Keyword(s):  
Root Hair ◽  
Glomus Intraradices ◽  
Lotus Japonicus ◽  
Am Fungi ◽  
Epidermal Cells ◽  
Parental Line ◽  
Entry Site ◽  
Symbiotic Interaction ◽  
Successful Infection ◽  
Infection Threads

The role of the Lotus japonicus LjSym4 gene during the symbiotic interaction with Mesorhizobium loti and arbuscular mycorrhizal (AM) fungi was analyzed with two mutant alleles conferring phenotypes of different strength. Ljsym4-1 and Ljsym4-2 mutants do not form nodules with M. loti.Normal root hair curling and infection threads are not observed, while a nodC-dependent deformation of root hair tips indicates that nodulation factors are still perceived by Ljsym4 mutants. Fungal infection attempts on the mutants generally abort within the epidermis, but Ljsym4-1 mutants allow rare, successful, infection events, leading to delayed arbuscule formation. On roots of mutants homozygous for the Ljsym4-2 allele, arbuscule formation was never observed upon inoculation with either of the two AM fungi, Glomus intraradices or Gigaspora margarita. The strategy of epidermal penetration by G. margarita was identical for Ljsym4-2 mutants and the parental line, with appressoria, hyphae growing between two epidermal cells, penetration of epidermal cells through their anticlinal wall. These observations define a novel, genetically controlled step in AM colonization. Although rhizobia penetrate the tip of root hairs and AM fungi access an entry site near the base of epidermal cells, the LjSym4 gene is necessary for the appropriate response of this cell type to both microsymbionts. We propose that LjSym4 is required for the initiation or coordinated expression of the host plant cell's accommodation program, allowing the passage of both microsymbionts through the epidermis layer.

scholarly journals Expression of Maize and Fungal Nitrate Reductase Genes in Arbuscular Mycorrhiza

1998 ◽  
Vol 11 (6) ◽  
pp. 439-448 ◽  
Author(s):  
Michael Kaldorf ◽  
Elmon Schmelzer ◽  
Hermann Bothe
Keyword(s):  
Nitrate Reductase ◽  
Glomus Intraradices ◽  
Mrna Level ◽  
Nitrate Assimilation ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Gene Coding ◽  
Polymerase Chain Reaction Technology ◽  
Am Fungus

The role of arbuscular mycorrhizal (AM) fungi in assisting their host plant in nitrate assimilation was studied. With polymerase chain reaction technology, part of the gene coding for the nitrate reductase (NR) apoprotein from either the AM fungus Glomus intraradices or from maize was specifically amplified and subsequently cloned and sequenced. Northern (RNA) blot analysis with these probes indicated that the mRNA level of the maize gene was lower in roots and shoots of mycorrhizal plants than in noncolonized controls, whereas the fungal gene was transcribed in roots of AM plants. The specific NR activity of leaves was significantly lower in AM-colonized maize than in the controls. Nitrite formation catalyzed by NR was mainly NADPH-dependent in roots of AM-colonized plants but not in those of the controls, which is consistent with the fact that NRs of fungi preferentially utilize NADPH as reductant. The fungal NR mRNA was detected in arbuscules but not in vesicles by in situ RNA hybridization experiments. This appears to be the first demonstration of differential formation of transcripts of a gene coding for the same function in both symbiotic partners.

scholarly journals Target of rapamycin, PvTOR, is a key regulator of arbuscule development during mycorrhizal symbiosis in Phaseolus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manoj-Kumar Arthikala ◽  
Kalpana Nanjareddy ◽  
Lourdes Blanco ◽  
Xóchitl Alvarado-Affantranger ◽  
Miguel Lara
Keyword(s):  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Target Of Rapamycin ◽  
Mycorrhizal Symbiosis ◽  
Energy Status ◽  
Symbiotic Associations ◽  
Expression Of Genes ◽  
Fungal Symbiosis ◽  
Am Fungus ◽  
Am Symbiosis

AbstractTarget of rapamycin (TOR) is a conserved central growth regulator in eukaryotes that has a key role in maintaining cellular nutrient and energy status. Arbuscular mycorrhizal (AM) fungi are mutualistic symbionts that assist the plant in increasing nutrient absorption from the rhizosphere. However, the role of legume TOR in AM fungal symbiosis development has not been investigated. In this study, we examined the function of legume TOR in the development and formation of AM fungal symbiosis. RNA-interference-mediated knockdown of TOR transcripts in common bean (Phaseolus vulgaris) hairy roots notably suppressed AM fungus-induced lateral root formation by altering the expression of root meristem regulatory genes, i.e., UPB1, RGFs, and sulfur assimilation and S-phase genes. Mycorrhized PvTOR-knockdown roots had significantly more extraradical hyphae and hyphopodia than the control (empty vector) roots. Strong promoter activity of PvTOR was observed at the site of hyphal penetration and colonization. Colonization along the root length was affected in mycorrhized PvTOR-knockdown roots and the arbuscules were stunted. Furthermore, the expression of genes induced by AM symbiosis such as SWEET1, VPY, VAMP713, and STR was repressed under mycorrhized conditions in PvTOR-knockdown roots. Based on these observations, we conclude that PvTOR is a key player in regulating arbuscule development during AM symbiosis in P. vulgaris. These results provide insight into legume TOR as a potential regulatory factor influencing the symbiotic associations of P. vulgaris and other legumes.

scholarly journals Intraradical Dynamics of Two Coexisting Isolates of the Arbuscular Mycorrhizal Fungus Glomus intraradices Sensu Lato as Estimated by Real-Time PCR of Mitochondrial DNA

2012 ◽  
Vol 78 (10) ◽  
pp. 3630-3637 ◽  
Author(s):  
Karol Krak ◽  
Martina Janoušková ◽  
Petra Caklová ◽  
Miroslav Vosátka ◽  
Helena Štorchová
Keyword(s):  
Mitochondrial Dna ◽  
Real Time ◽  
Real Time Pcr ◽  
Glomus Intraradices ◽  
Large Subunit ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Content Type ◽  
Copy Numbers ◽  
Pcr Assays

ABSTRACTReal-time PCR in nuclear ribosomal DNA (nrDNA) is becoming a well-established tool for the quantification of arbuscular mycorrhizal (AM) fungi, but this genomic region does not allow the specific amplification of closely related genotypes. The large subunit of mitochondrial DNA (mtDNA) has a higher-resolution power, but mtDNA-based quantification has not been previously explored in AM fungi. We applied real-time PCR assays targeting the large subunit of mtDNA to monitor the DNA dynamics of two isolates ofGlomus intraradicessensu lato coexisting in the roots of medic (Medicago sativa). The mtDNA-based quantification was compared to quantification in nrDNA. The ratio of copy numbers determined by the nrDNA- and mtDNA-based assays consistently differed between the two isolates. Within an isolate, copy numbers of the nuclear and the mitochondrial genes were closely correlated. The two quantification approaches revealed similar trends in the dynamics of both isolates, depending on whether they were inoculated alone or together. After 12 weeks of cultivation, competition between the two isolates was observed as a decrease in the mtDNA copy numbers of one of them. The coexistence of two closely related isolates, which cannot be discriminated by nrDNA-based assays, was thus identified as a factor influencing the dynamics of AM fungal DNA in roots. Taken together, the results of this study show that real-time PCR assays targeted to the large subunit of mtDNA may become useful tools for the study of coexisting AM fungi.

scholarly journals Lipo-chitooligosaccharide Signaling in Endosymbiotic Plant-Microbe Interactions

2011 ◽  
Vol 24 (8) ◽  
pp. 867-878 ◽  
Author(s):  
Clare Gough ◽  
Julie Cullimore
Keyword(s):  
Glomus Intraradices ◽  
Mutual Recognition ◽  
Arbuscular Mycorrhizal ◽  
Defense Responses ◽  
Fungal Cell ◽  
Root Branching ◽  
Bacterial Endosymbionts ◽  
Microbe Interactions ◽  
Am Fungus ◽  
Am Symbiosis

The arbuscular mycorrhizal (AM) and the rhizobia-legume (RL) root endosymbioses are established as a result of signal exchange in which there is mutual recognition of diffusible signals produced by plant and microbial partners. It was discovered 20 years ago that the key symbiotic signals produced by rhizobial bacteria are lipo-chitooligosaccharides (LCO), called Nod factors. These LCO are perceived via lysin-motif (LysM) receptors and activate a signaling pathway called the common symbiotic pathway (CSP), which controls both the RL and the AM symbioses. Recent work has established that an AM fungus, Glomus intraradices, also produces LCO that activate the CSP, leading to induction of gene expression and root branching in Medicago truncatula. These Myc-LCO also stimulate mycorrhization in diverse plants. In addition, work on the nonlegume Parasponia andersonii has shown that a LysM receptor is required for both successful mycorrhization and nodulation. Together these studies show that structurally related signals and the LysM receptor family are key components of both nodulation and mycorrhization. LysM receptors are also involved in the perception of chitooligosaccharides (CO), which are derived from fungal cell walls and elicit defense responses and resistance to pathogens in diverse plants. The discovery of Myc-LCO and a LysM receptor required for the AM symbiosis, therefore, not only raises questions of how legume plants discriminate fungal and bacterial endosymbionts but also, more generally, of how plants discriminate endosymbionts from pathogenic microorganisms using structurally related LCO and CO signals and of how these perception mechanisms have evolved.

scholarly journals Stable C and N isotope natural abundances of intraradical hyphae of arbuscular mycorrhizal fungi

Mycorrhiza ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 773-780
Author(s):  
Saskia Klink ◽  
Philipp Giesemann ◽  
Timo Hubmann ◽  
Johanna Pausch
Keyword(s):  
Mycorrhizal Fungi ◽  
Isotope Composition ◽  
Fungal Spores ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mineral Nutrient ◽  
Carbohydrate Source ◽  
Lipid Source ◽  
Am Fungus ◽  
C And N

Abstract Data for stable C and N isotope natural abundances of arbuscular mycorrhizal (AM) fungi are currently sparse, as fungal material is difficult to access for analysis. So far, isotope analyses have been limited to lipid compounds associated with fungal membranes or storage structures (biomarkers), fungal spores and soil hyphae. However, it remains unclear whether any of these components are an ideal substitute for intraradical AM hyphae as the functional nutrient trading organ. Thus, we isolated intraradical hyphae of the AM fungus Rhizophagus irregularis from roots of the grass Festuca ovina and the legume Medicago sativa via an enzymatic and a mechanical approach. In addition, extraradical hyphae were isolated from a sand-soil mix associated with each plant. All three approaches revealed comparable isotope signatures of R. irregularis hyphae. The hyphae were 13C- and 15N-enriched relative to leaves and roots irrespective of the plant partner, while they were enriched only in 15N compared with soil. The 13C enrichment of AM hyphae implies a plant carbohydrate source, whereby the enrichment was likely reduced by an additional plant lipid source. The 15N enrichment indicates the potential of AM fungi to gain nitrogen from an organic source. Our isotope signatures of the investigated AM fungus support recent findings for mycoheterotrophic plants which are suggested to mirror the associated AM fungi isotope composition. Stable isotope natural abundances of intraradical AM hyphae as the functional trading organ for bi-directional carbon-for-mineral nutrient exchanges complement data on spores and membrane biomarkers.

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