scholarly journals Spatiotemporal cytokinin response imaging and ISOPENTENYLTRANSFERASE 3 function in Medicago nodule development

2021 ◽  
Author(s):  
Paolo M Triozzi ◽  
Thomas B Irving ◽  
Henry W Schmidt ◽  
Zachary P Keyser ◽  
Sanhita Chakraborty ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nodule Development ◽  
Symbiotic Association ◽  
Loss Of Function ◽  
Tissue Specific ◽  
Temporal Regulation ◽  
Positive Regulators ◽  
Sequential Activation

Abstract Most legumes can establish a symbiotic association with soil rhizobia that trigger the development of root nodules. These nodules host the rhizobia and allow them to fix nitrogen efficiently. The perception of bacterial lipo-chitooligosaccharides (LCOs) in the epidermis initiates a signaling cascade that allows rhizobial intracellular infection in the root and de-differentiation and activation of cell division that gives rise to the nodule. Thus, nodule organogenesis and rhizobial infection need to be coupled in space and time for successful nodulation. The plant hormone cytokinin (CK) contributes to the coordination of this process, acting as an essential positive regulator of nodule organogenesis. However, the temporal regulation of tissue-specific CK signaling and biosynthesis in response to LCOs or Sinorhizobium meliloti inoculation in Medicago truncatula remains poorly understood. In this study, using a fluorescence-based CK sensor (pTCSn::nls:tGFP), we performed a high-resolution tissue-specific temporal characterization of the sequential activation of CK response during root infection and nodule development in M. truncatula after inoculation with S. meliloti. Loss-of-function mutants of the CK-biosynthetic gene ISOPENTENYLTRANSFERASE 3 (IPT3) showed impairment of nodulation, suggesting that IPT3 is required for nodule development in M. truncatula. Simultaneous live imaging of pIPT3::nls:tdTOMATO and the CK sensor showed that IPT3 induction in the pericycle at the base of nodule primordium contributes to CK biosynthesis, which in turn promotes expression of positive regulators of nodule organogenesis in M. truncatula.

scholarly journals Spatiotemporal cytokinin signaling imaging reveals IPT3 function in nodule development in Medicago truncatula

2021 ◽  
Author(s):  
Paolo M. Triozzi ◽  
Thomas B. Irving ◽  
Henry W. Schmidt ◽  
Zachary P. Keyser ◽  
Sanhita Chakraborty ◽  
...  
Keyword(s):  
High Resolution ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nodule Development ◽  
Nodule Formation ◽  
Symbiotic Association ◽  
Loss Of Function ◽  
Cytokinin Signaling ◽  
Tissue Specific

ABSTRACTMost legumes can establish a symbiotic association with soil rhizobia that triggers the development of root nodules. These nodules host the rhizobia and allow them to fix nitrogen efficiently. The perception of bacterial lipo-chitooligosaccharide (LCO) signal in the epidermis initiates a signaling cascade that allows rhizobial intracellular infection in the root and de-differentiation and activation of cell division that gives rise to the nodule. Nodule organogenesis and rhizobial infection need to be coupled in space and time for successful nodulation. The plant hormone cytokinin (CK) acts as an essential positive regulator of nodule organogenesis, and specific CK receptors are required for nodule formation. Temporal regulation of tissue-specific CK signaling and biosynthesis in response to LCOs or Sinorhizobium meliloti inoculation in Medicago truncatula remains poorly understood. In the present study, using a fluorescence-based CK sensor (TCSn::nls:tGFP), we performed a high-resolution tissue-specific temporal characterization of the CK response’s sequential activation during root infection and nodule development in M. truncatula after inoculation with S. meliloti. Loss-of-function mutants of the CK-biosynthetic gene ISOPENTENYL TRANSFERASE 3 (IPT3) showed impairment of nodulation, suggesting that IPT3 is required for nodule development in M. truncatula. Simultaneous live imaging of pIPT3::tdTOMATO and the CK sensor showed that IPT3 induction in the root stele at the base of nodule primordium contributes to CK biosynthesis, which in turn promotes expression of positive regulators of nodule organogenesis in M. truncatula.One-sentence summaryHigh-resolution spatiotemporal imaging of cytokinin signaling reveals IPT3 function during indeterminate nodule development in Medicago truncatula

scholarly journals PvRACK1 Loss-of-Function Impairs Cell Expansion and Morphogenesis in Phaseolus vulgaris L. Root Nodules

2011 ◽  
Vol 24 (7) ◽  
pp. 819-826 ◽  
Author(s):  
Tania Islas-Flores ◽  
Gabriel Guillén ◽  
Xóchitl Alvarado-Affantranger ◽  
Miguel Lara-Flores ◽  
Federico Sánchez ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Cell Expansion ◽  
Root Nodules ◽  
Microscopic Analysis ◽  
Nodule Development ◽  
Loss Of Function ◽  
Rhizobium Tropici ◽  
Transcript Accumulation ◽  
Transgenic Roots ◽  
Plant Signal Transduction

Receptor for activated C kinase (RACK1) is a highly conserved, eukaryotic protein of the WD-40 repeat family. Its peculiar β-propeller structure allows its interaction with multiple proteins in various plant signal-transduction pathways, including those arising from hormone responses, development, and environmental stress. During Phaseolus vulgaris root development, RACK1 (PvRACK1) mRNA expression was induced by auxins, abscissic acid, cytokinin, and gibberellic acid. In addition, during P. vulgaris nodule development, PvRACK1 mRNA was highly accumulated at 12 to 15 days postinoculation, suggesting an important role after nodule meristem initiation and Rhizobium nodule infection. PvRACK1 transcript accumulation was downregulated by a specific RNA interference construct which was expressed in transgenic roots of composite plants of P. vulgaris inoculated with Rhizobium tropici. PvRACK1 downregulated transcript levels were monitored by quantitative reverse-transcription polymerase chain reaction analysis in individual transgenic roots and nodules. We observed a clear phenotype in PvRACK1-knockdown nodules, in which nodule number and nodule cell expansion were impaired, resulting in altered nodule size. Microscopic analysis indicated that, in PvRACK1-knockdown nodules, infected and uninfected cells were considerably smaller (80 and 60%, respectively) than in control nodules. In addition, noninfected cells and symbiosomes in silenced nodules showed significant defects in membrane structure under electron microscopy analysis. These findings indicate that PvRACK1 has a pivotal role in cell expansion and in symbiosome and bacteroid integrity during nodule development.

scholarly journals MtBZR1 Plays an Important Role in Nodule Development in Medicago truncatula

2019 ◽  
Vol 20 (12) ◽  
pp. 2941
Author(s):  
Can Cui ◽  
Hongfeng Wang ◽  
Limei Hong ◽  
Yiteng Xu ◽  
Yang Zhao ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Normal Growth ◽  
Dry Mass ◽  
Growth Conditions ◽  
Nodule Development ◽  
Functional Study ◽  
Loss Of Function ◽  
Wild Type

Brassinosteroid (BR) is an essential hormone in plant growth and development. The BR signaling pathway was extensively studied, in which BRASSINAZOLE RESISTANT 1 (BZR1) functions as a key regulator. Here, we carried out a functional study of the homolog of BZR1 in Medicago truncatula R108, whose expression was induced in nodules upon Sinorhizobium meliloti 1021 inoculation. We identified a loss-of-function mutant mtbzr1-1 and generated 35S:MtBZR1 transgenic lines for further analysis at the genetic level. Both the mutant and the overexpression lines of MtBZR1 showed no obvious phenotypic changes under normal growth conditions. After S. meliloti 1021 inoculation, however, the shoot and root dry mass was reduced in mtbzr1-1 compared with the wild type, caused by partially impaired nodule development. The transcriptomic analysis identified 1319 differentially expressed genes in mtbzr1-1 compared with wild type, many of which are involved in nodule development and secondary metabolite biosynthesis. Our results demonstrate the role of MtBZR1 in nodule development in M. truncatula, shedding light on the potential role of BR in legume–rhizobium symbiosis.

scholarly journals Molecular Cloning and Characterization of cgt, the Brucella abortus Cyclic β-1,2-Glucan Transporter Gene, and Its Role in Virulence

2004 ◽  
Vol 72 (4) ◽  
pp. 2263-2271 ◽  
Author(s):  
Mara S. Roset ◽  
Andrés E. Ciocchini ◽  
Rodolfo A. Ugalde ◽  
Nora Iñón de Iannino
Keyword(s):  
Brucella Abortus ◽  
Sinorhizobium Meliloti ◽  
Nodule Development ◽  
Nucleotide Sequencing ◽  
Nodule Occupancy ◽  
Transporter Gene ◽  
Binding Motifs ◽  
Reading Frame ◽  
Intracellular Multiplication

ABSTRACT The animal pathogen Brucella abortus contains a gene cgt, which complemented Sinorhizobium meliloti nodule development (ndvA) and Agrobacterium tumefaciens chromosomal virulence (chvA) mutants. Complemented strains recovered the presence of anionic cyclic β-1,2-glucan, motility, tumor induction in A. tumefaciens, and nodule occupancy in S. meliloti, all traits strictly associated with the presence of cyclic β-1,2-glucan in the periplasm. Nucleotide sequencing revealed that B. abortus cgt contains a 1,797-bp open reading frame coding for a predicted membrane protein of 599 amino acids (65.9 kDa) that is 58.5 and 59.9% identical to S. meliloti NdvA and A. tumefaciens ChvA, respectively. Additionally, B. abortus cgt, like S. meliloti ndvA and A. tumefaciens chvA possesses ATP-binding motifs and the ABC signature domain features of a typical ABC transporter. Characterization of Cgt was carried out by the construction of null mutants in B. abortus 2308 and S19 backgrounds. Both mutants do not transport cyclic β-1,2-glucan to the periplasm, as shown by the absence of anionic cyclic glucan, and they display reduced virulence in mice and defective intracellular multiplication in HeLa cells. These results suggest that cyclic β-1,2-glucan must be transported into the periplasmatic space to exert its action as a virulence factor.

scholarly journals Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility

2015 ◽  
Vol 112 (49) ◽  
pp. 15244-15249 ◽  
Author(s):  
Paul A. Price ◽  
Houston R. Tanner ◽  
Brett A. Dillon ◽  
Mohammed Shabab ◽  
Graham C. Walker ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nodule Development ◽  
Range Restriction ◽  
Peptide Cleavage ◽  
Bacterial Proliferation ◽  
Naturally Occurring ◽  
Signaling Peptides ◽  
Late Stages ◽  
Host Range Restriction

Legume–rhizobium pairs are often observed that produce symbiotic root nodules but fail to fix nitrogen. Using the Sinorhizobium meliloti and Medicago truncatula symbiotic system, we previously described several naturally occurring accessory plasmids capable of disrupting the late stages of nodule development while enhancing bacterial proliferation within the nodule. We report here that host range restriction peptidase (hrrP), a gene found on one of these plasmids, is capable of conferring both these properties. hrrP encodes an M16A family metallopeptidase whose catalytic activity is required for these symbiotic effects. The ability of hrrP to suppress nitrogen fixation is conditioned upon the genotypes of both the host plant and the hrrP-expressing rhizobial strain, suggesting its involvement in symbiotic communication. Purified HrrP protein is capable of degrading a range of nodule-specific cysteine-rich (NCR) peptides encoded by M. truncatula. NCR peptides are crucial signals used by M. truncatula for inducing and maintaining rhizobial differentiation within nodules, as demonstrated in the accompanying article [Horváth B, et al. (2015) Proc Natl Acad Sci USA, 10.1073/pnas.1500777112]. The expression pattern of hrrP and its effects on rhizobial morphology are consistent with the NCR peptide cleavage model. This work points to a symbiotic dialogue involving a complex ensemble of host-derived signaling peptides and bacterial modifier enzymes capable of adjusting signal strength, sometimes with exploitative outcomes.

scholarly journals Characterization of the Twin-Arginine Transport Secretome in Sinorhizobium meliloti and Evidence for Host-Dependent Phenotypes

2012 ◽  
Vol 78 (19) ◽  
pp. 7141-7144 ◽  
Author(s):  
Brad S. Pickering ◽  
Harry Yudistira ◽  
Ivan J. Oresnik
Keyword(s):  
Cell Viability ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Sweet Clover ◽  
Content Type ◽  
Arginine Transport ◽  
Plant Hosts ◽  
Tat System

ABSTRACTThe twin-arginine transport (Tat) system is essential for cell viability inSinorhizobium melilotiand may play a role during the development of root nodules. Utilizing anin vivorecombination strategy, we have constructed 28 strains that contain deletions in predicted Tat substrates. Testing of these mutations for symbiotic proficiency on the plant hosts alfalfa and sweet clover shows that some of these mutations affect associations with these hosts differentially.

scholarly journals Circadian Regulation of a Drosophila Homolog of the Mammalian Clock Gene: PER and TIM Function as Positive Regulators

1998 ◽  
Vol 18 (10) ◽  
pp. 6142-6151 ◽  
Author(s):  
Kiho Bae ◽  
Choogon Lee ◽  
David Sidote ◽  
Keng-yu Chuang ◽  
Isaac Edery
Keyword(s):  
Circadian Clock ◽  
Clock Gene ◽  
Clock Genes ◽  
Temporal Regulation ◽  
Helix Loop Helix ◽  
Circadian Oscillators ◽  
Drosophila Homolog ◽  
Circadian Clock Genes ◽  
Positive Regulators

ABSTRACT The Clock gene plays an essential role in the manifestation of circadian rhythms (≅24 h) in mice and is a member of the basic helix-loop-helix (bHLH) PER-ARNT-SIM (PAS) superfamily of transcription factors. Here we report the characterization of a novelDrosophila bHLH-PAS protein that is highly homologous to mammalian CLOCK. (Similar findings were recently described by Allada et al. Cell 93:791–804, 1998, and Darlington et al., Science 280:1599–1603, 1998.) Transcripts from this putative Clockortholog (designated dClock) undergo daily rhythms in abundance that are antiphase to the cycling observed for the RNA products from the Drosophila melanogaster circadian clock genes period (per) and timeless(tim). Furthermore, dClock RNA cycling is abolished and the levels are at trough values in the absence of either PER or TIM, suggesting that these two proteins can function as transcriptional activators, a possibility which is in stark contrast to their previously characterized role in transcriptional autoinhibition. Finally, the temporal regulation of dClock expression is quickly perturbed by shifts in light-dark cycles, indicating that this molecular rhythm is closely connected to the photic entrainment pathway. The isolation of a Drosophila homolog ofClock together with the recent discovery of mammalian homologs of per indicate that there is high structural conservation in the integral components underlying circadian oscillators in Drosophila and mammals. Nevertheless, because mammalian Clock mRNA is constitutively expressed, our findings are a further example of striking differences in the regulation of putative circadian clock orthologs in different species.

scholarly journals Determinants of Host Range Specificity in Legume-Rhizobia Symbiosis

2020 ◽  
Vol 11 ◽  
Author(s):  
Liam Walker ◽  
Beatriz Lagunas ◽  
Miriam L. Gifford
Keyword(s):  
Host Range ◽  
Host Plant ◽  
Molecular Mechanisms ◽  
High Efficiency ◽  
Current Knowledge ◽  
Root Nodules ◽  
Partner Choice ◽  
Nodule Development ◽  
Symbiotic Association ◽  
Nitrogen Fixing

Leguminous plants possess the almost unique ability to enter symbiosis with soil-resident, nitrogen fixing bacteria called rhizobia. During this symbiosis, the bacteria physically colonize specialized organs on the roots of the host plant called nodules, where they reduce atmospheric nitrogen into forms that can be assimilated by the host plant and receive photosynthates in return. In order for nodule development to occur, there is extensive chemical cross-talk between both parties during the formative stages of the symbiosis. The vast majority of the legume family are capable of forming root nodules and typically rhizobia are only able to fix nitrogen within the context of this symbiotic association. However, many legume species only enter productive symbiosis with a few, or even single rhizobial species or strains, and vice-versa. Permitting symbiosis with only rhizobial strains that will be able to fix nitrogen with high efficiency is a crucial strategy for the host plant to prevent cheating by rhizobia. This selectivity is enforced at all stages of the symbiosis, with partner choice beginning during the initial communication between the plant and rhizobia. However, it can also be influenced even once nitrogen-fixing nodules have developed on the root. This review sets out current knowledge about the molecular mechanisms employed by both parties to influence host range during legume-rhizobia symbiosis.

scholarly journals Glycine-Rich Proteins Encoded by a Nodule-Specific Gene Family Are Implicated in Different Stages of Symbiotic Nodule Development in Medicago Spp.

2002 ◽  
Vol 15 (9) ◽  
pp. 922-931 ◽  
Author(s):  
Zoltán Kevei ◽  
José María Vinardell ◽  
György B. Kiss ◽  
Adam Kondorosi ◽  
Eva Kondorosi
Keyword(s):  
Bacterial Infection ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Gene Activation ◽  
Nodule Development ◽  
Specific Gene ◽  
Amino Terminal ◽  
Repeat Structure ◽  
Small Proteins ◽  
Genes Encoding

Four genes encoding small proteins with significantly high glycine content have been identified from root nodules of Medicago sativa. All of these proteins as well as their Medicago truncatula homologues carried an amino terminal signal peptide and a glycine-rich carboxy terminal domain. All except nodGRP3 lacked the characteristic repeat structure described for cell wall and stress response-related glycinerich proteins (GRP). Expression of these GRP genes was undetectable in flower, leaf, stem, and hypocotyl cells, whereas expression was highly induced during root nodule development, suggesting that GRP genes act as nodulins. Moreover, none of these nodule-expressed GRP genes were activated by hormones or stress treatments, which are inducers of many other GRPs. In Rhizobium-free spontaneous nodules and in nodules induced by a noninfective mutant strain of Sinorhizobium meliloti, all these genes were repressed, while they were induced in Fix¯ nodules, unaffected in bacterial infection, but halted in bacteroid differentiation. These results demonstrated that bacterial infection but not bacteroid differentiation is required for the induction of the nodule-specific GRP genes. Differences in kinetics and localization of gene activation as well as in the primary structure of proteins suggest nonredundant roles for these GRPs in nodule organogenesis.

scholarly journals Characterization of the growth of Rhizobium trifolii and Sinorhizobium meliloti in different culture media

2013 ◽  
Vol 70 (1) ◽  
pp. 80-86
Author(s):  
Monica NISTE ◽  
Roxana VIDICAN ◽  
Ioan ROTAR ◽  
Rodica POP
Keyword(s):  
Sinorhizobium Meliloti ◽  
Trifolium Pratense ◽  
Culture Media ◽  
Root Nodules ◽  
Plant Host ◽  
Symbiotic Interactions ◽  
Rhizobium Strains ◽  
Yeast Extract Mannitol ◽  
Different Strains

Legumes have the ability to form symbiotic interactions with soil bacteria, called rhizobia. Bacteria of the genus Rhizobium are able to convert atmospheric nitrogen into ammonia when compounds are exchanged between the bacteroid and its plant host. The present study describes the characterization of Rhizobium strains isolated from root nodules of Trifolium pratense and Medicago sativa grown in a greenhouse. The main objective of the experiment was to identify which medium is more suitable for the development of different strains of rhizobia. The Rhizobium strains are rod shaped, Gram negative and mucus producing. The rhizobia were identified and isolated using different media yeast extract mannitol agar (YEMA) containing Congo red, and a medium including boron (B), an essential micronutrient. The Petri plates were incubated at 28ºC and inspected three days after the inoculation. The colony morphology was analysed based on type, appearance, transparency, colour and the effectiveness of boron on Rhizobium growth.

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