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 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 Defects in Rhizobial Cyclic Glucan and Lipopolysaccharide Synthesis Alter Legume Gene Expression During Nodule Development

2008 ◽  
Vol 21 (1) ◽  
pp. 50-60 ◽  
Author(s):  
Alejandra L. D'Antuono ◽  
Thomas Ott ◽  
Lene Krusell ◽  
Vera Voroshilova ◽  
Rodolfo A. Ugalde ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mutant Strain ◽  
Early Recognition ◽  
Lotus Japonicus ◽  
Cdna Array ◽  
Nodule Development ◽  
Marker Genes ◽  
Wild Type ◽  
Mesorhizobium Loti ◽  
Expression Of Genes

cDNA array technology was used to compare transcriptome profiles of Lotus japonicus roots inoculated with a Mesorhizobium loti wild-type and two mutant strains affected in cyclic β(1-2) glucan synthesis (cgs) and in lipopolysaccharide synthesis (lpsβ2). Expression of genes associated with the development of a fully functional nodule was significantly affected in plants inoculated with the cgs mutant. Array results also revealed that induction of marker genes for nodule development was delayed when plants were inoculated with the lpsβ2 mutant. Quantitative real-time reverse-transcriptase polymerase chain reaction was used to quantify gene expression of a subset of genes involved in plant defense response, redox metabolism, or genes that encode for nodulins. The majority of the genes analyzed in this study were more highly expressed in roots inoculated with the wild type compared with those inoculated with the cgs mutant strain. Some of the genes exhibited a transient increase in transcript levels during intermediate steps of normal nodule development while others displayed induced expression during the final steps of nodule development. Ineffective nodules induced by the glucan mutant showed higher expression of phenylalanine ammonia lyase than wild-type nodules. Differences in expression pattern of genes involved in early recognition and signaling were observed in plants inoculated with the M. loti mutant strain affected in the synthesis of cyclic glucan.

scholarly journals Whole-Genome Sequence of the Nitrogen-Fixing Symbiotic Rhizobium Mesorhizobium loti Strain TONO

2016 ◽  
Vol 4 (5) ◽  
Author(s):  
Yoshikazu Shimoda ◽  
Hideki Hirakawa ◽  
Shusei Sato ◽  
Kazuhiko Saeki ◽  
Makoto Hayashi
Keyword(s):  
Comparative Genomics ◽  
Genome Sequence ◽  
Lotus Japonicus ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Nitrogen Fixing ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Symbiotic Properties

Mesorhizobium loti is the nitrogen-fixing microsymbiont for legumes of the genus Lotus . Here, we report the whole-genome sequence of a Mesorhizobium loti strain, TONO, which is used as a symbiont for the model legume Lotus japonicus . The whole-genome sequence of the strain TONO will be a solid platform for comparative genomics analyses and for the identification of genes responsible for the symbiotic properties of Mesorhizobium species.

scholarly journals Spontaneous Root-Nodule Formation in the Model Legume Lotus japonicus: A Novel Class of Mutants Nodulates in the Absence of Rhizobia

2006 ◽  
Vol 19 (4) ◽  
pp. 373-382 ◽  
Author(s):  
Leïla Tirichine ◽  
Euan K. James ◽  
Niels Sandal ◽  
Jens Stougaard
Keyword(s):  
Root Nodule ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Nodule Formation ◽  
Wild Type ◽  
Model Legume ◽  
Isolation And Characterization ◽  
Mutant Lines ◽  
Spontaneous Nodules

Root-nodule development in legumes is an inducible developmental process initially triggered by perception of lipochitin-oligosaccharide signals secreted by the bacterial microsymbiont. In nature, rhizobial colonization and invasion of the legume root is therefore a prerequisite for formation of nitrogen-fixing root nodules. Here, we report isolation and characterization of chemically induced spontaneously nodulating mutants in a model legume amenable to molecular genetics. Six mutant lines of Lotus japonicus were identified in a screen for spontaneous nodule development under axenic conditions, i.e., in the absence of rhizobia. Spontaneous nodules do not contain rhizobia, bacteroids, or infection threads. Phenotypically, they resemble ineffective white nodules formed by some bacterial mutants on wild-type plants or certain plant mutants inoculated with wild-type Mesorhizobium loti. Spontaneous nodules formed on mutant lines show the ontogeny and characteristic histological features described for rhizobia-induced nodules on wild-type plants. Physiological responses to nitrate and ethylene are also maintained, as elevated levels inhibit spontaneous nodulation. Activation of the nodule developmental program in spontaneous nodules was shown for the early nodulin genes Enod2 and Nin, which are both upregulated in spontaneous nodules as well as in rhizobial nodules. Both monogenic recessive and dominant spontaneous nodule formation (snf) mutations were isolated in this mutant screen, and map positions were determined for three loci. We suggest that future molecular characterization of these mutants will identify key plant determinants involved in regulating nodulation and provide new insight into plant organ development.

scholarly journals Mutants of Lotus japonicus deficient in flavonoid biosynthesis

2021 ◽  
Vol 134 (2) ◽  
pp. 341-352
Author(s):  
Toshio Aoki ◽  
Masayoshi Kawaguchi ◽  
Haruko Imaizumi-Anraku ◽  
Shoichiro Akao ◽  
Shin-ichi Ayabe ◽  
...  
Keyword(s):  
Anthocyanin Biosynthesis ◽  
Lotus Japonicus ◽  
Flavonoid Biosynthesis ◽  
Anthocyanin Accumulation ◽  
Type B ◽  
Wild Type ◽  
Ems Mutagenesis ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Wild Accessions

AbstractSpatiotemporal features of anthocyanin accumulation in a model legumeLotus japonicus(Regel) K.Larsen were elucidated to develop criteria for the genetic analysis of flavonoid biosynthesis. Artificial mutants and wild accessions, with lower anthocyanin accumulation in the stem than the standard wild type (B-129 ‘Gifu’), were obtained by ethyl methanesulfonate (EMS) mutagenesis and from a collection of wild-grown variants, respectively. The loci responsible for the green stem of the mutants were named asVIRIDICAULIS(VIC). Genetic and chemical analysis identified two loci, namely,VIC1andVIC2, required for the production of both anthocyanins and proanthocyanidins (condensed tannins), and two loci, namely,VIC3andVIC4, required for the steps specific to anthocyanin biosynthesis. A mutation inVIC5significantly reduced the anthocyanin accumulation. These mutants will serve as a useful system for examining the effects of anthocyanins and proanthocyanidins on the interactions with herbivorous pests, pathogenic microorganisms and nitrogen-fixing symbiotic bacteria,Mesorhizobium loti.

scholarly journals Αναπρογραμματισμός του μεταβολισμού του Lotus japonicus σε μεταγραφικό, βιοχημικό και μεταβολομικό επίπεδο κατά τη συμβιωτική αζωτοδέσμευση

2016 ◽  
Author(s):  
Χρυσάνθη Καλλονιάτη
Keyword(s):  
Nitrogen Fixation ◽  
Metabolite Profiling ◽  
Symbiotic Nitrogen Fixation ◽  
Sulfur Metabolism ◽  
Lotus Japonicus ◽  
Nitrogen Fixing ◽  
Model Legume ◽  
Whole Plant ◽  
Plant Level ◽  
Molecular And Biochemical Mechanisms

Symbiotic nitrogen fixation in legumes takes place in specialized organs called nodules,which become the main source of assimilated nitrogen for the whole plant. Symbiotic nitro‐gen fixation requires exquisite integration of plant and bacterial metabolism and involvesglobal changes in gene expression and metabolite accumulation in both rhizobia and thehost plant. In order to study the metabolic changes mediated by symbiotic nitrogen fixationon a whole‐plant level, metabolite levels were profiled by gas chromatography–mass spec‐trometry in nodules and non‐symbiotic organs of Lotus japonicus plants uninoculated or in‐oculated with M. loti wt,  ΔnifA or  ΔnifH fix‐ strains. Furthermore, transcriptomic andbiochemical approaches were combined to study sulfur metabolism in nodules, its link tosymbiotic nitrogen fixation, and the effect of nodules on whole‐plant sulfur partitioning andmetabolism. It is well established that nitrogen and sulfur (S) metabolism are tightly en‐twined and sulfur is required for symbiotic nitrogen fixation, however, little is known aboutthe molecular and biochemical mechanisms governing sulfur uptake and assimilation duringsymbiotic nitrogen fixation. Transcript profiling in Lotus japonicus was combined with quan‐tification of S‐metabolite contents and APR activity in nodules and in non‐symbiotic organsof plants uninoculated or inoculated with M. loti wt, ΔnifA or ΔnifH fix‐ strains. Moreover,sulfate uptake and its distribution into different plant organs were analyzed and 35S‐flux intodifferent S‐pools was monitored. Metabolite profiling revealed that symbiotic nitrogen fixa‐tion results in dramatic changes of many aspects of primary and secondary metabolism innodules which leads to global reprogramming of metabolism of the model legume on awhole‐plant level. Moreover, our data revealed that nitrogen fixing nodules represent athiol‐rich organ. Their high APR activity and 35S‐flux into cysteine and its metabolites in com‐bination with the transcriptional up‐regulation of several genes involved in sulfur assimila‐tion highlight the function of nodules as a new site of sulfur assimilation. The higher thiolcontent observed in non‐symbiotic organs of nitrogen fixing plants in comparison touninoculated plants cannot be attributed to local biosynthesis, indicating that nodules couldserve as a novel source of reduced sulfur for the plant, which triggers whole‐plant repro‐gramming of sulfur metabolism. Interestingly, the changes in metabolite profiling and theenhanced thiol biosynthesis in nodules and their impact on the whole‐plant sulfur, carbonand nitrogen economy are dampened in fix‐ plants, which in most respects metabolically re‐sembled uninoculated plants, indicating a strong interaction between nitrogen fixation andsulfur and carbon metabolism.

scholarly journals Expression Islands Clustered on the Symbiosis Island of the Mesorhizobium loti Genome

2004 ◽  
Vol 186 (8) ◽  
pp. 2439-2448 ◽  
Author(s):  
Toshiki Uchiumi ◽  
Takuji Ohwada ◽  
Manabu Itakura ◽  
Hisayuki Mitsui ◽  
Noriyuki Nukui ◽  
...  
Keyword(s):  
Acid Metabolism ◽  
Symbiotic Nitrogen Fixation ◽  
Transcriptional Profiling ◽  
Lotus Japonicus ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Genome Region ◽  
Transcriptional Dynamics ◽  
Rhizobial Symbiosis ◽  
Highly Expressed Genes

ABSTRACT Rhizobia are symbiotic nitrogen-fixing soil bacteria that are associated with host legumes. The establishment of rhizobial symbiosis requires signal exchanges between partners in microaerobic environments that result in mutualism for the two partners. We developed a macroarray for Mesorhizobium loti MAFF303099, a microsymbiont of the model legume Lotus japonicus, and monitored the transcriptional dynamics of the bacterium during symbiosis, microaerobiosis, and starvation. Global transcriptional profiling demonstrated that the clusters of genes within the symbiosis island (611 kb), a transmissible region distinct from other chromosomal regions, are collectively expressed during symbiosis, whereas genes outside the island are downregulated. This finding implies that the huge symbiosis island functions as clustered expression islands to support symbiotic nitrogen fixation. Interestingly, most transposase genes on the symbiosis island were highly upregulated in bacteroids, as were nif, fix, fdx, and rpoN. The genome region containing the fixNOPQ genes outside the symbiosis island was markedly upregulated as another expression island under both microaerobic and symbiotic conditions. The symbiosis profiling data suggested that there was activation of amino acid metabolism, as well as nif-fix gene expression. In contrast, genes for cell wall synthesis, cell division, DNA replication, and flagella were strongly repressed in differentiated bacteroids. A highly upregulated gene in bacteroids, mlr5932 (encoding 1-aminocyclopropane-1-carboxylate deaminase), was disrupted and was confirmed to be involved in nodulation enhancement, indicating that disruption of highly expressed genes is a useful strategy for exploring novel gene functions in symbiosis.

A D-pinitol transporter, LjPLT11, regulates plant growth and nodule development in Lotus japonicus

2021 ◽  
Author(s):  
Lu Tian ◽  
Leru Liu ◽  
Shaoming Xu ◽  
Rufang Deng ◽  
Pingzhi Wu ◽  
...  
Keyword(s):  
Plant Growth ◽  
Nitrogenase Activity ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Xenopus Laevis Oocytes ◽  
Oxygen Species ◽  
In Planta ◽  
Osmotic Balance ◽  
Infected Cells ◽  
Functional Analyses

Abstract Polyol transporters (PLTs) have been functionally characterized in yeast and Xenopus laevis oocytes as H +-symporters with broad substrate specificity, but little is known about their physiological roles in planta. To extend this knowledge we investigated roles of LjPLT11 in Lotus japonicus-Mesorhizobium symbiosis. Functional analyses of the LjPLT11 in yeast characterized this protein as an energy-independent transporter of xylitol, two O-methyl inositols, xylose and galactose. We also showed that LjPLT11 is located on peribacteroid membranes (PBMs) and functions as a facilitative transporter of D-pinitol within infected cells of L. japonicus nodules. Knockdown of LjPLT11 (LjPLT11i) in L. japonicus accelerated plant growth under nitrogen-sufficiency, but resulted in abnormal bacteroids with corresponding reductions in nitrogenase activity in nodules and plant growth in the nitrogen-fixing symbiosis. LjPLT11i nodules had higher osmotic pressure in cytosol and fewer in bacteroids than wildtype nodules both three and four weeks after inoculation of M. loti. Levels and distributions of reactive oxygen species were also perturbed in infected cells of four-week-old nodules in LjPLT11i plants. The results indicate that LjPLT11 plays a key role in adjustment of levels of its substrate pinitol, and thus maintenance of osmotic balance in infected cells and PBM stability during nodule development.

Glutamine synthetase I-deficiency in Mesorhizobium loti differentially affects nodule development and activity in Lotus japonicus

2014 ◽  
Vol 171 (5) ◽  
pp. 104-108 ◽  
Author(s):  
Sirinapa Chungopast ◽  
Pilunthana Thapanapongworakul ◽  
Hiroyuki Matsuura ◽  
Tan Van Dao ◽  
Toshimasa Asahi ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Mesorhizobium Loti ◽  
Glutamine Synthetase I

scholarly journals Responses of a Model Legume Lotus japonicus to Lipochitin Oligosaccharide Nodulation Factors Purified from Mesorhizobium loti JRL501

2001 ◽  
Vol 14 (7) ◽  
pp. 848-856 ◽  
Author(s):  
Shinobu Niwa ◽  
Masayoshi Kawaguchi ◽  
Haruko Imaizumi-Anraku ◽  
Svetlana A. Chechetka ◽  
Masumi Ishizaka ◽  
...  
Keyword(s):  
High Performance ◽  
Molecular Genetic ◽  
Lotus Japonicus ◽  
Cytoplasmic Bridge ◽  
Cortical Cells ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Root Hair Deformation ◽  
Early Nodulin ◽  
Microbe Interactions

Lotus japonicus has been proposed as a model legume for molecular genetic studies of symbiotic plant-microbe interactions leading to the fixation of atmospheric nitrogen. Lipochitin oligosaccharides (LCOs), or Nod factors, were isolated from the culture of Mesorhizobium loti strain JRL501 (MAFF303099), an efficient microsymbiont of L. japonicus B-129 cv. Gifu. High-performance liquid chromatography and mass spectrometric analyses allowed us to identify at least five different structures of LCOs that were produced by JRL501. The major component was NodMl-V(C18:1, Me, Cb, AcFuc), an N-acetyl-glucosamine pentamer in which the nonreducing residue is N-acylated with a C18:1 acyl moiety, N-methylated, and carries a carbamoyl group and the reducing N-acetyl-glucosamine residue is substituted with 4-O-acetyl-fucose. Additional novel LCO structures bearing fucose instead of acetyl-fucose at the reducing end were identified. Mixtures of these LCOs could elicit abundant root hair deformation on L. japonicus roots at a concentration of 10-7 to 10-9 M. Spot inoculation of a few nanograms of LCOs on L. japonicus roots induced the formation of nodule primordia in which the early nodulin genes, ENOD40 and ENOD2, were expressed in a tissue-specific manner. We also observed the formation of a cytoplasmic bridge (preinfection thread) in the swollen outermost cortical cells. This is the first description of cytoplasmic bridge formation by purified LCOs alone in a legume-forming determinate nodules.

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