scholarly journals Endophytic Colonization of Rice (Oryza sativa L.) by the Symbiotic Strain Nostoc punctiforme PCC 73102

2020 ◽  
Vol 33 (8) ◽  
pp. 1040-1045
Author(s):  
Consolación Álvarez ◽  
José A. Navarro ◽  
Fernando P. Molina-Heredia ◽  
Vicente Mariscal
Keyword(s):  
Nitrogenase Activity ◽  
Oryza Sativa L ◽  
Nitrogen Deficiency ◽  
Nitrogen Fixing ◽  
Nostoc Punctiforme ◽  
Terrestrial Plants ◽  
Symbiotic Associations ◽  
Beneficial Effects ◽  
Hydroponic Cultures ◽  
Structural Levels

Cyanobacteria are phototrophic microorganisms able to establish nitrogen-fixing symbiotic associations with representatives of all four of the major phylogenetic divisions of terrestrial plants. Despite increasing knowledge on the beneficial effects of cyanobacteria in rice fields, the information about the interaction between these microorganisms and rice at the molecular and structural levels is still limited. We have used the model nitrogen-fixing cyanobacterium Nostoc punctiforme to promote a long-term stable endophytic association with rice. Inoculation with this strain of hydroponic cultures of rice produces a fast adherence of the cyanobacterium to rice roots. At longer times, cyanobacterial growth in the proximity of the roots increased until reaching a plateau. This latter phase coincides with the intracellular colonization of the root epidermis and exodermis. Structural analysis of the roots revealed that the cyanobacterium use an apoplastic route to colonize the plant cells. Moreover, plant roots inoculated with N. punctiforme show both the presence of heterocysts and nitrogenase activity, resulting in the promotion of plant growth under nitrogen deficiency, thus providing benefits for the plant.

Tripartite associations in snowbrush (Ceanothus velutinus): effect of vesicular–arbuscular mycorrhizae on growth, nodulation, and nitrogen fixation

1981 ◽  
Vol 59 (1) ◽  
pp. 34-39 ◽  
Author(s):  
S. L. Rose ◽  
C. T. Youngberg
Keyword(s):  
Host Plant ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Nitrogenase Activity ◽  
Mycorrhizal Fungus ◽  
Nodule Formation ◽  
Nitrogen Fixing ◽  
Symbiotic Associations ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi

Symbiotic associations were established between nitrogen-fixing nonleguminous (actinorrhizal) snowbrush (Ceanothus velutinus Dougl.) seedlings and two categories of microorganisms: vesicular–arbuscular (VA) mycorrhizal fungi and a filamentous actinomycete capable of inducing nodule formation. The actinomycete is housed in nodules where fixation of atmospheric dinitrogen occurs and is made available to the host plant; the mycorrhizal fungus is both inter- and intra-cellular within the root tissue and may be found within the nodules. The two major nutrients, N and P, are made available and can be supplied to the host plant by these two symbiotic microorganisms. The root system of snowbrush seedlings was dually colonized by VA mycorrhizal fungi and a nitrogen-fixing actinomycete and the possibility of a direct interaction between the endophytes in the symbioses was investigated. Dually infected plants showed increases in total dry weight of shoots and roots, number of nodules, weight of nodular tissue, as well as higher levels of N, Ca2+, and P, and an increase in nitrogenase activity as measured by acetylene reduction.

scholarly journals Integrative Transcriptomic and Proteomic Analysis Reveals an Alternative Molecular Network of Glutamine Synthetase 2 Corresponding to Nitrogen Deficiency in Rice (Oryza sativa L.)

2021 ◽  
Vol 22 (14) ◽  
pp. 7674
Author(s):  
Ting Liang ◽  
Zhengqing Yuan ◽  
Lu Fu ◽  
Menghan Zhu ◽  
Xiaoyun Luo ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Oryza Sativa L ◽  
Alternative Pathway ◽  
Rice Variety ◽  
Nitrogen Deficiency ◽  
Primary Root ◽  
Phenotypic Characterization ◽  
Glutathione Metabolism ◽  
N Assimilation ◽  
N Deficiency

Nitrogen (N) is an essential nutrient for plant growth and development. The root system architecture is a highly regulated morphological system, which is sensitive to the availability of nutrients, such as N. Phenotypic characterization of roots from LY9348 (a rice variety with high nitrogen use efficiency (NUE)) treated with 0.725 mM NH4NO3 (1/4N) was remarkable, especially primary root (PR) elongation, which was the highest. A comprehensive analysis was performed for transcriptome and proteome profiling of LY9348 roots between 1/4N and 2.9 mM NH4NO3 (1N) treatments. The results indicated 3908 differential expression genes (DEGs; 2569 upregulated and 1339 downregulated) and 411 differential abundance proteins (DAPs; 192 upregulated and 219 downregulated). Among all DAPs in the proteome, glutamine synthetase (GS2), a chloroplastic ammonium assimilation protein, was the most upregulated protein identified. The unexpected concentration of GS2 from the shoot to the root in the 1/4N treatment indicated that the presence of an alternative pathway of N assimilation regulated by GS2 in LY9348 corresponded to the low N signal, which was supported by GS enzyme activity and glutamine/glutamate (Gln/Glu) contents analysis. In addition, N transporters (NRT2.1, NRT2.2, NRT2.3, NRT2.4, NAR2.1, AMT1.3, AMT1.2, and putative AMT3.3) and N assimilators (NR2, GS1;1, GS1;2, GS1;3, NADH-GOGAT2, and AS2) were significantly induced during the long-term N-deficiency response at the transcription level (14 days). Moreover, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that phenylpropanoid biosynthesis and glutathione metabolism were significantly modulated by N deficiency. Notably, many transcription factors and plant hormones were found to participate in root morphological adaptation. In conclusion, our study provides valuable information to further understand the response of rice roots to N-deficiency stress.

scholarly journals Rhizobium tropici Genes Involved in Free-Living Salt Tolerance are Required for the Establishment of Efficient Nitrogen-Fixing Symbiosis with Phaseolus vulgaris

2002 ◽  
Vol 15 (3) ◽  
pp. 225-232 ◽  
Author(s):  
Joaquina Nogales ◽  
Rosario Campos ◽  
Hanaa BenAbdelkhalek ◽  
José Olivares ◽  
Carmen Lluch ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Phaseolus Vulgaris ◽  
Environmental Changes ◽  
Nitrogenase Activity ◽  
Regulation Of Gene Expression ◽  
Elongation Factor ◽  
Regulatory System ◽  
Trna Synthetase ◽  
Nitrogen Fixing ◽  
Rhizobium Tropici

Characterization of nine transposon-induced mutants of Rhizobium tropici with decreased salt tolerance (DST) allowed the identification of eight gene loci required for adaptation to high external NaCl. Most of the genes also were involved in adaptation to hyperosmotic media and were required to overcome the toxicity of LiCl. According to their possible functions, genes identified could be classified into three groups. The first group included two genes involved in regulation of gene expression, such as ntrY, the sensor element of the bacterial ntrY/ntrX two-component regulatory system involved in regulation of nitrogen metabolism, and greA, which encodes a transcription elongation factor. The second group included genes related to synthesis, assembly, or maturation of proteins, such as alaS coding for alanine-tRNA synthetase, dnaJ, which encodes a molecular chaperone, and a nifS homolog probably encoding a cysteine desulfurase involved in the maturation of Fe-S proteins. Genes related with cellular build-up and maintenance were in the third group, such as a noeJ-homolog, encoding a mannose-1-phosphate guanylyltransferase likely involved in lipopolysaccharide biosynthesis, and kup, specifying an inner-membrane protein involved in potassium uptake. Another gene was identified that had no homology to known genes but that could be conserved in other rhizobia. When inoculated on Phaseolus vulgaris growing under nonsaline conditions, all DST mutants displayed severe symbiotic defects: ntrY and noeJ mutants were impaired in nodulation, and the remaining mutants formed symbiosis with very reduced nitrogenase activity. The results suggest that bacterial ability to adapt to hyper-osmotic and salt stress is important for the bacteroid nitrogen-fixing function inside the legume nodule and provide genetic evidence supporting the suggestion that rhizobia face severe environmental changes after their release into plant cells.

New marine nitrogen-fixing bacteria isolated from an eelgrass (Zostera marina) bed

1988 ◽  
Vol 34 (7) ◽  
pp. 886-890 ◽  
Author(s):  
Wung Yang Shieh ◽  
Usio Simidu ◽  
Yoshiharu Maruyama
Keyword(s):  
Zostera Marina ◽  
Nitrogenase Activity ◽  
Molecular Nitrogen ◽  
Exponential Growth Phase ◽  
Nitrogen Fixing ◽  
Low Oxygen ◽  
Nitrogen Fixing Bacteria ◽  
Nitrogen Fixation Activity ◽  
The Family ◽  
Ph Decrease

Four strains of marine nitrogen-fixing bacteria were isolated from the roots of eelgrass (Zostera marina) and from sediments in an eelgrass bed in Aburatsubo Inlet, Kanagawa Prefecture, Japan. Significant levels of nitrogenase activity were detected in all four strains after a few hours of incubation under anaerobic conditions. Nitrogenase activity in all cases was Na+ dependent. These strains grew anaerobically or under conditions of low oxygen, using molecular nitrogen as the sole nitrogen source. Bacterial growth in liquid nitrogen-free medium was accompanied by a marked pH decrease during the exponential growth phase. Neither yeast extract nor vitamins were required for the nitrogen fixation activity of these strains. Taxonomically, all strains were facultatively anaerobic, Gram-negative rods. They were motile in liquid medium by means of a single polar flagellum and required NaCl for their growth. These characteristics, as well as the guanine + cytosine content of their DNA (43.5 – 44.8 mol%), placed them in the family Vibrionaceae. These strains, however, could not be identified to the genus level because they were distinct from the two halophilic genera Vibrio and Photobacterium of the family Vibrionaceae by a variety of characteristics.

Nitrogen fixation

1976 ◽  
Vol 274 (934) ◽  
pp. 341-358 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Metabolic Regulation ◽  
Higher Plants ◽  
Focal Point ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Blue Green Algae ◽  
International Biological Programme ◽  
The 1960S ◽  
Biological Programme

The International Biological Programme served as a focal point for studies on biological nitrogen fixation during the 1960s. The introduction of the acetylene reduction technique for measuring nitrogenase activity in the field led to estimates becoming available of the contribution of lichens, blue-green algae, nodulated non-legumes and bacterial-grass associations, as well as of legumes. Other studies carried out on the physiology and biochemistry of the process led to the eventual purification and characterization of the nitrogenase enzyme. These studies, collectively, provided the springboard for current work, so essential in view of the present energy crisis, on how to increase the use and efficiency of nitrogen-fixing plants, on the metabolic regulation of the nitrogenase enzyme and on the genetics of the nitrogen-fixing process, both in higher plants and in free-living micro-organisms.

Optimal conditions for induction of competence in nitrogen-fixing Azotobacter vinelandii

1982 ◽  
Vol 28 (4) ◽  
pp. 389-397 ◽  
Author(s):  
William J. Page
Keyword(s):  
Dissolved Oxygen ◽  
Sodium Acetate ◽  
Azotobacter Vinelandii ◽  
Nitrogenase Activity ◽  
Cell Mass ◽  
Apparent Competition ◽  
Competence Development ◽  
Optimal Conditions ◽  
Nitrogen Fixing ◽  
Ph Range

Competence development in nitrogen-fixing Azotobacter vinelandii cells was optimal at pH 7.2–7.4 which necessitated additional buffering of the iron-limited nitrogen-free competence medium or the addition of a suitable organic acid salt, e.g., sodium acetate. An autolysin was active in this pH range and competent cells were more susceptible to autolysis than the general cell population. Competence development also required restricted aeration of the culture, and only those cultures that attained zero dissolved oxygen became competent. Restricted aeration served to protect the iron-limited cell nitrogenase from oxygen inactivation thus allowing the culture to reach zero dissolved oxygen. The inclusion of additional sources of reductant, e.g., malate, in buffered competence medium resulted in increased respiration and protection of nitrogenase, increased cell mass, and poly-β-hydroxybutyrate synthesis, but decreased competence. A possible explanation for the apparent competition between competence development and nitrogenase activity is discussed.

scholarly journals Screening of Nitrogen Fixing Endophytic Bacteria in Oryza sativa L.

2014 ◽  
Vol 6 (6) ◽  
Author(s):  
Prathana Hongrittipun ◽  
Somchit Youpensuk ◽  
Benjavan Rerkasem
Keyword(s):  
Oryza Sativa ◽  
Endophytic Bacteria ◽  
Oryza Sativa L ◽  
Nitrogen Fixing

scholarly journals Nitrogen-fixing bacteria and Oxalis – evidence for a vertically inherited bacterial symbiosis

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Michelle Jooste ◽  
Francois Roets ◽  
Guy F. Midgley ◽  
Kenneth C. Oberlander ◽  
Léanne L. Dreyer
Keyword(s):  
Endophytic Bacteria ◽  
Sequence Data ◽  
Fluorescent Microscopy ◽  
Nitrogen Deficiency ◽  
Nitrogen Fixing ◽  
Vertical Inheritance ◽  
Bacterial Symbiosis ◽  
Plant Growth Promoting ◽  
Potential Benefits ◽  
Exclusion Experiments

Abstract Background Plant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly to crop plants, and to date no such system has been reported for geophytes. Methods Bacterial endophytes associated with Oxalis, the most species-rich geophytic genus form the Cape Flora in southern Africa was studied. Culturable endophytes were isolated from surface-sterilized vegetative and reproductive plant organs for six host species at three locations. Colonies of microbes on various artificial media were morphotyped, enumerated and identified using sequence data. Filter exclusion experiments were conducted to determine if endophytes were vertically transmitted to seeds, determine if mucilage plays a role to actively attract microbes from the soil and to assess microbial richness isolated from the mucilage of Oxalis seedlings. Fluorescent microscopy was implemented in order to visualize endophytic bacteria in cryo-sectioned seeds. Results Evidence for a novel, vertically transmitted symbiosis was reported. Communities of nitrogen-fixing and plant growth-promoting Bacillus endophytes were found to associate with selected Oxalis hosts from nitrogen-deficient environments of the Cape. Bacillus endophytes were ubiquitous and diverse across species and plant bodies, and were prominent in seeds. Three common nitrogen-fixing Bacillus have known oxalotrophic properties and appear to be housed inside specialised cavities (containing oxalates) within the plant body and seeds. Conclusions The discovery of vertical transmission and potential benefits to both host and endophyte suggest a particularly tight mutualism in the Oxalis-endophyte system. This discovery suggests unexpected ways in which geophytes might avoid nitrogen deficiency, and suggest that such symbioses are more common than previously expected.

scholarly journals The nitrogen-fixing symbiotic cyanobacterium, Nostoc punctiforme can regulate plant programmed cell death

2020 ◽  
Author(s):  
Samuel P. Belton ◽  
Paul F. McCabe ◽  
Carl K. Y. Ng
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Molecular Mechanisms ◽  
Differential Regulation ◽  
Nitrogen Fixing ◽  
Nostoc Punctiforme ◽  
Transcriptional Reprogramming ◽  
Cell Growth And Differentiation ◽  
Transcriptome Resource ◽  
Developmental Signalling

AbstractCyanobacteria such as Nostoc spp. can form nitrogen-fixing symbioses with a broad range of plant species. Unlike other plant-bacteria symbioses, little is understood about the immunological and developmental signalling events induced by Nostoc cyanobionts (symbiotic cyanobacteria). Here, we used suspension cell cultures to elucidate the early molecular mechanisms underpinning the association between cyanobionts and plants by studying the effects of conditioned medium (CM) from Nostoc punctiforme cultures on plant programmed cell death (PCD), a typical immune response activated during incompatible interactions. We showed that N. punctiforme-CM could suppress PCD induced by a temperature stress. Interestingly, this was preceded by significant transcriptional reprogramming, as evidenced by the differential regulation of a network of defence-associated genes, as well as genes implicated in regulating cell growth and differentiation. This work is the first to show that cyanobionts can regulate PCD in plants and provides a valuable transcriptome resource for the early immunological and developmental signalling events elicited by Nostoc cyanobionts.

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