scholarly journals Lotus japonicus Forms Early Senescent Root Nodules with Rhizobium etli

2001 ◽  
Vol 14 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Mari Banba ◽  
Abu-Baker M. Siddique ◽  
Hiroshi Kouchi ◽  
Katsura Izui ◽  
Shingo Hata
Keyword(s):  
Root Nodules ◽  
Nitrogen Deficiency ◽  
Lotus Japonicus ◽  
Acetylene Reduction Activity ◽  
Rhizobium Etli ◽  
Transcription Activator ◽  
Membrane Structures ◽  
Mesorhizobium Loti ◽  
Reduction Activity ◽  
Infected Cells

Mesorhizobium loti and Rhizobium etli are microsymbionts of the Lotus and Phaseolus spp., respectively, and secrete essentially the same Nod factors. Lotus japonicus efficiently formed root nodules with R. etli CE3, irrespective of the presence or absence of a flavonoid-independent transcription activator nodD gene. On a nitrogen-free medium, however, the host plant inoculated with R. etli showed a severe nitrogen deficiency symptom. Initially, the nodules formed with R. etli were pale pink and leghemoglobin mRNA was detectable at significant levels. Nevertheless, the nodules became greenish with time. Acetylene-reduction activity of nodules formed with R. etli was comparable with that formed by M. loti 3 weeks postinoculation, but thereafter it decreased rapidly. The nodules formed with R. etli contained much more starch granules than those formed with M. loti. R. etli developed into bacteroids in the L. japonicus nodules, although the density of bacteroids in the infected cells was lower than that in the nodules formed with M. loti. The nodules formed with R. etli were of the early senescence type, in that membrane structures were drastically disintegrated in the infected cells of the greenish nodules. Thus, L. japonicus started and then ceased a symbiotic relationship with R. etli at the final stage.

scholarly journals A Novel Fix¯ Symbiotic Mutant of Lotus japonicus, Ljsym105, Shows Impaired Development and Premature Deterioration of Nodule Infected Cells and Symbiosomes

2006 ◽  
Vol 19 (7) ◽  
pp. 780-788 ◽  
Author(s):  
Md. Shakhawat Hossain ◽  
Yosuke Umehara ◽  
Hiroshi Kouchi
Keyword(s):  
Nitrogen Deficiency ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Acetylene Reduction Activity ◽  
Nitrogen Fixing ◽  
Wild Type ◽  
Electron Microscopic ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Infected Cells

Nitrogen-fixing symbiosis between legume plants and rhizobia is established through complex interactions between two symbiotic partners. To identify the host legume genes that play crucial roles in such interactions, we isolated a novel Fix¯ mutant, Ljsym105, from a model legume Lotus japonicus MG-20. The Ljsym105 plants displayed nitrogen-deficiency symptoms after inoculation with Mesorhizobium loti under nitrogen-free conditions, but their growth recovered when supplied with nitrogen-rich nutrients. Ljsym105 was recessive and monogenic and mapped on the upper portion of chromosome 4. The mutant Ljsym105 formed an increased number of small and pale-pink nodules. Nitrogenase (acetylene reduction) activity per nodule fresh weight was low but retained more than 50% of that of the wild-type nodules. Light and electron microscopic observations revealed that the Ljsym105 nodule infected cells were significantly smaller than those of wild-type plants, contained enlarged symbiosomes with multiple bacteroids, and underwent deterioration of the symbiosomes prematurely as well as disintegration of the whole infected cell cytoplasm. These results indicate that the ineffectiveness of the Ljsym105 nodules is primarily due to impaired growth of infected cells accompanied with the premature senescence induced at relatively early stages of nodule development. These symbiotic phenotypes are discussed in respect to possible functions of the LjSym105 locus in the symbiotic interactions required for establishment of the nitrogen-fixing symbiosis.

scholarly journals Photorespiratory Metabolism and Nodule Function: Behavior of Lotus japonicus Mutants Deficient in Plastid Glutamine Synthetase

2012 ◽  
Vol 25 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Margarita García-Calderón ◽  
Maurizio Chiurazzi ◽  
M. Rosario Espuny ◽  
Antonio J. Márquez
Keyword(s):  
Nitrogen Fixation ◽  
Glutamine Synthetase ◽  
Carbon Metabolism ◽  
Lotus Japonicus ◽  
Acetylene Reduction Activity ◽  
Symbiotic Association ◽  
Atmospheric Nitrogen ◽  
Mesorhizobium Loti ◽  
Reduction Activity ◽  
Air Atmosphere

Two photorespiratory mutants of Lotus japonicus deficient in plastid glutamine synthetase (GS2) were examined for their capacity to establish symbiotic association with Mesorhizobium loti bacteria. Biosynthetic glutamine synthetase (GS) activity was reduced by around 40% in crude nodule extracts from mutant plants as compared with the wild type (WT). Western blot analysis further confirmed the lack of GS2 polypeptide in mutant nodules. The decrease in GS activity affected the nodular carbon metabolism under high CO2 (suppressed photorespiration) conditions, although mutant plants were able to form nodules and fix atmospheric nitrogen. However, when WT and mutant plants were transferred to an ordinary air atmosphere (photorespiratory active conditions) the nodulation process and nitrogen fixation were substantially affected, particularly in mutant plants. The number and fresh weight of mutant nodules as well as acetylene reduction activity showed a strong inhibition compared with WT plants. Optical microscopy studies from mutant plant nodules revealed the anticipated senescence phenotype linked to an important reduction in starch and sucrose levels. These results show that, in Lotus japonicus, photorespiration and, particularly, GS2 deficiency result in profound limitations in carbon metabolism that affect the nodulation process and nitrogen fixation.

scholarly journals Differential Effects of Combined N Sources on Early Steps of the Nod Factor–Dependent Transduction Pathway in Lotus japonicus

2007 ◽  
Vol 20 (8) ◽  
pp. 994-1003 ◽  
Author(s):  
Ani Barbulova ◽  
Alessandra Rogato ◽  
Enrica D'Apuzzo ◽  
Selim Omrane ◽  
Maurizio Chiurazzi
Keyword(s):  
Root Nodules ◽  
Lotus Japonicus ◽  
Small Scale ◽  
Nodule Formation ◽  
Inhibitory Effects ◽  
Nod Factor ◽  
Mesorhizobium Loti ◽  
N Sources ◽  
N Starvation ◽  
And Function

The development of nitrogen-fixing nodules in legumes is induced by perception of lipochitin-oligosaccharide signals secreted by a bacterial symbiont. Nitrogen (N) starvation is a prerequisite for the formation, development, and function of root nodules, and high levels of combined N in the form of nitrate or ammonium can completely abolish nodule formation. We distinguished between nitrate and ammonium inhibitory effects by identifying when and where these combined N sources interfere with the Nod-factor-induced pathway. Furthermore, we present a small-scale analysis of the expression profile, under different N conditions, of recently identified genes involved in the Nod-factor-induced pathway. In the presence of high levels of nitrate or ammonium, the NIN gene fails to be induced 24 h after the addition of Nod factor compared with plants grown under N-free conditions. This induction is restored in the hypernodulating nitrate-tolerant har1-3 mutant only in the presence of 10 and 20 mM KNO3. These results were confirmed in Lotus plants inoculated with Mesorhizobium loti. NIN plays a key role in the nodule organogenesis program and its downregulation may represent a crucial event in the nitrate-dependent pathway leading to the inhibition of nodule organogenesis.

Relative contributions to nitrogenase (acetylene reducing) activity of stem and root nodules in Sesbania rostrata

1992 ◽  
Vol 38 (6) ◽  
pp. 577-583 ◽  
Author(s):  
J. K. Ladha ◽  
Minviluz Garcia ◽  
R. P. Pareek ◽  
G. Rarivoson
Keyword(s):  
Acetylene Reduction ◽  
Root Nodule ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Dry Weight ◽  
Acetylene Reduction Activity ◽  
Sesbania Rostrata ◽  
Reduction Activity ◽  
Acetylene Reducing Activity ◽  
Aerial Stem

Six experiments, two each in the phytotron, greenhouse, and field, were conducted to assess the contribution of nitrogenase activity (acetylene reduction) by stem nodules in the presence and absence of root nodules of Sesbania rostrata (Brem & Oberm). In a greenhouse experiment, the effect of detaching already formed aerial stem nodules on the restoration of root nodules and nitrogenase activity was studied. The field experiment compared nodulation and acetylene-reduction activity by dual-nodulating S. rostrata and root-nodulating Sesbania cannabina. Acetylene-reduction activity expressed per gram of nodule dry weight was higher for stem nodules than for root nodules. Root nodule dry weight and acetylene-reduction activity failed to increase after stem inoculation, but root nodule dry weight and acetylene-reduction activity increased several fold within 15 days of detachment of aerial stem nodules. Stem nodulation, which occurred without inoculation under lowland field condition, suppressed root nodulation, thus accounting for more than 75% of total nitrogenase activity. Sesbania rostrata showed higher acetylene-reduction activity than S. cannabina. In dual-nodulating plants, root and stem nodules appeared to strike a balance in competition for energy, which may be controlled by stem nodulation. Key words: Sesbania rostrata, Azorhizobium caulinodans, stem nodule, root nodule, acetylene-reducing activity.

An SEM/TEM study of structures associated with bacteroids in peanut (Arachis hyppogaea L.) root nodules

1988 ◽  
Vol 46 ◽  
pp. 288-289
Author(s):  
C. J. Emerson ◽  
A. K. Bal
Keyword(s):  
Arachis Hypogaea ◽  
Acetylene Reduction ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Root Nodules ◽  
Acetylene Reduction Activity ◽  
Reduction Activity ◽  
Dense Bodies ◽  
Growth Chambers ◽  
Large Spherical

Nitrogen-fixing peanut root nodules have highly specialized, large spherical bacteroids and show higher acetylene-reduction activity than the nodules of other legumes induced by the same strain of rhizobia. Differences are also found in their anatomical organization and with regard to bacteroid-associated organelles and other structures (dense bodies) found on the host-symbiont interface. In this investigation, further description of these organelles and structures was made at different stages of development in a correlated SEM/TEM study.Arachis hypogaea L. cv. Jumbo Virginia plants were grown in environmental growth chambers and inoculated with Rhizobium sp. 32Hl. For TEM, slices of nodules were fixed in Karnovsky's fixative in Sorensen's phosphate buffer, pH 7.2 for 1 h at 4°C. Tissues were rinsed in buffer, post-fixed with 1% phosphate-buffered osmium tetroxide for 1 h at 4°C and dehydrated in ethanol. 1% p-phenylenediamine was added at the 70% ethanol step (30 min) to preserve lipids.

scholarly journals Tissue-Specific Transcriptome Analysis in Nodules of Lotus japonicus

2012 ◽  
Vol 25 (7) ◽  
pp. 869-876 ◽  
Author(s):  
Kojiro Takanashi ◽  
Hirokazu Takahashi ◽  
Nozomu Sakurai ◽  
Akifumi Sugiyama ◽  
Hideyuki Suzuki ◽  
...  
Keyword(s):  
Transcriptome Analysis ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Phenylpropanoid Pathway ◽  
Specific Expression ◽  
Model Legume ◽  
Tissue Specific ◽  
Highly Expressed Genes ◽  
Infected Cells ◽  
Nitrogen Nutrients

Legume plants can establish symbiotic nitrogen fixation (SNF) with rhizobia mostly in root nodules, where rhizobia-infected cells are accompanied by uninfected cells in a mosaic pattern. Inside the mature nodules of the legume, carbon and nitrogen nutrients between host plant cells and their resident bacteria are actively exchanged. To elucidate the metabolite dynamics relevant for SNF in nodules, three tissues from a nodule of a model legume, Lotus japonicus, were isolated using laser microdissesction, and transcriptome analysis was done by an oligoarray of 60-mer length representing 21,495 genes. In our tissue-specific profiling, many genes were identified as being expressed in nodules in a spatial-specific manner. Among them, genes coding for metabolic enzymes were classified according to their function, and detailed data analysis showed that a secondary metabolic pathway was highly activated in the nodule cortex. In particular, a number of metabolic genes for a phenylpropanoid pathway were found as highly expressed genes accompanied by those encoding putative transporters of secondary metabolites. These data suggest the involvement of a novel physiological function of phenylpropanoids in SNF. Moreover, five representative genes were selected, and detailed tissue-specific expression was characterized by promoter-β-glucuronidase experiments. Our results provide a new data source for investigation of both nodule differentiation and tissue-specific physiological functions in nodules.

scholarly journals Expressed Sequence Tags from Roots and Nodule Primordia of Lotus japonicus Infected with Mesorhizobium loti

2002 ◽  
Vol 15 (4) ◽  
pp. 376-379 ◽  
Author(s):  
Carsten Poulsen ◽  
Lone Pødenphant
Keyword(s):  
Expressed Sequence Tags ◽  
Messenger Rna ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Cdna Expression Library ◽  
Expression Library ◽  
Mesorhizobium Loti ◽  
Pcr Products ◽  
Plant Genes ◽  
Expressed Sequence

Messenger RNA from young Lotus japonicus roots carrying root nodule primordia appearing after inoculation with Mesorhizobium loti bacteria were used to construct a cDNA expression library. Single-pass sequencing employing colony-polymerase chain reaction (PCR) and analysis of PCR products established a total of 2,397 new expressed sequence tags (ESTs). We have putatively identified 1,236 known and 484 hypothetical proteins coded by the corresponding mRNAs. The remaining cDNAs are unknown (316) or redundant overlapping cDNAs (361). We hope that this batch of ESTs will assist in the recognition of plant genes involved during development of nitrogen-fixing root nodules.

scholarly journals Mesorhizobium loti Produces nodPQ-Dependent Sulfated Cell Surface Polysaccharides

2006 ◽  
Vol 188 (24) ◽  
pp. 8560-8572 ◽  
Author(s):  
Guy E. Townsend ◽  
Lennart S. Forsberg ◽  
David H. Keating
Keyword(s):  
Growth Rate ◽  
Cell Surface ◽  
Capsular Polysaccharide ◽  
Physiological Function ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Sulfated Polysaccharides ◽  
Nodule Formation ◽  
Mesorhizobium Loti ◽  
Surface Polysaccharides

ABSTRACT Leguminous plants and bacteria from the family Rhizobiaceae form a symbiotic relationship, which culminates in novel plant structures called root nodules. The indeterminate symbiosis that forms between Sinorhizobium meliloti and alfalfa requires biosynthesis of Nod factor, a β-1,4-linked lipochitooligosaccharide that contains an essential 6-O-sulfate modification. S. meliloti also produces sulfated cell surface polysaccharides, such as lipopolysaccharide (LPS). The physiological function of sulfated cell surface polysaccharides is unclear, although mutants of S. meliloti with reduced LPS sulfation exhibit symbiotic abnormalities. Using a bioinformatic approach, we identified a homolog of the S. meliloti carbohydrate sulfotransferase, LpsS, in Mesorhizobium loti. M. loti participates in a determinate symbiosis with the legume Lotus japonicus. We showed that M. loti produces sulfated forms of LPS and capsular polysaccharide (KPS). To investigate the physiological function of sulfated polysaccharides in M. loti, we identified and disabled an M. loti homolog of the sulfate-activating genes, nodPQ, which resulted in undetectable amounts of sulfated cell surface polysaccharides and a cysteine auxotrophy. We concomitantly disabled an M. loti cysH homolog, which disrupted cysteine biosynthesis without reducing cell surface polysaccharide sulfation. Our experiments demonstrated that the nodPQ mutant, but not the cysH mutant, showed an altered KPS structure and a diminished ability to elicit nodules on its host legume, Lotus japonicus. Interestingly, the nodPQ mutant also exhibited a more rapid growth rate and appeared to outcompete wild-type M. loti for nodule colonization. These results suggest that sulfated cell surface polysaccharides are required for optimum nodule formation but limit growth rate and nodule colonization in M. loti.

scholarly journals Expression of the 1-Aminocyclopropane-1-Carboxylic Acid Deaminase Gene Requires Symbiotic Nitrogen-Fixing Regulator Gene nifA2 in Mesorhizobium loti MAFF303099

2006 ◽  
Vol 72 (7) ◽  
pp. 4964-4969 ◽  
Author(s):  
Noriyuki Nukui ◽  
Kiwamu Minamisawa ◽  
Shin-Ichi Ayabe ◽  
Toshio Aoki
Keyword(s):  
Carboxylic Acid ◽  
Soil Bacteria ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Acc Deaminase ◽  
Regulator Gene ◽  
Gene Encoding ◽  
Mesorhizobium Loti ◽  
Reverse Transcription Pcr ◽  
Enhanced Expression

ABSTRACT Many soil bacteria contain 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, which degrades ACC, a precursor of the phytohormone ethylene. In order to examine the regulation of the acdS gene encoding ACC deaminase in Mesorhizobium loti MAFF303099 during symbiosis with the host legume Lotus japonicus, we introduced the β-glucuronidase (GUS) gene into acdS so that GUS was expressed under control of the acdS promoter, and we also generated disruption mutants with mutations in a nitrogen fixation regulator gene, nifA. The histochemical GUS assay showed that there was exclusive expression of acdS in mature root nodules. Two homologous nifA genes, mll5857 and mll5837, were found in the symbiosis island of M. loti and were designated nifA1 and nifA2, respectively. Quantitative reverse transcription-PCR demonstrated that nifA2 disruption resulted in considerably diminished expression of acdS, nifH, and nifA1 in bacteroid cells. In contrast, nifA1 disruption slightly enhanced expression of the acdS transcripts and suppressed nifH to some extent. These results indicate that the acdS gene and other symbiotic genes are positively regulated by the NifA2 protein, but not by the NifA1 protein, in M. loti. The mode of gene expression suggests that M. loti acdS participates in the establishment and/or maintenance of mature nodules by interfering with the production of ethylene, which induces negative regulation of nodulation.

Effects of Protein Synthesis Inhibitors on Acetylene Reduction Activity of Lupin Root Nodules

1980 ◽  
Vol 7 (3) ◽  
pp. 261 ◽  
Author(s):  
WD Sutton
Keyword(s):  
Protein Synthesis ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Acetylene Reduction Activity ◽  
Cytoplasmic Protein ◽  
Protein Synthesis Inhibitors ◽  
Cytoplasmic Fraction ◽  
Reduction Activity ◽  
Pure Cultures

Rifampicin and D-threo-chloramphenicol inhibited the incorporation of [35S]methionine into purified bacteroid suspensions, and into the bacteroid fraction but not the plant cytoplasmic fraction of cultured nodules. Cycloheximide and anisomycin inhibited [35S]methionine incorporation into the plant cytoplasmic fraction of cultured nodules; at early times they inhibited incorporation into the bacteroid fraction, but at later times this effect was reversed. Chloramphenicol, rifampicin, spectinomycin, cycloheximide and anisomycin all prevented the induction of acetylene reduction activity in immature nodules; spectinomycin did not prevent induction in nodules containing a spectinomycin-resistant Rhizobium. Neither rifampicin nor chloramphenicol inhibited the acetylene reduction activity of mature nodules, but cycloheximide and anisomycin caused rapid loss of activity. Cycloheximide did not inhibit the acetylene reduction activity of Rhizobium strain 32H1 in pure cultures. The results suggest that both plant cytoplasmic protein synthesis and bacteroid protein synthesis are needed for the induction of nitrogenase activity in developing lupin nodules, and that plant cytoplasmic protein synthesis but not bacteroid protein synthesis is needed for the maintenance of nitrogenase activity at high levels.

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