A morphometric study of effective nodules induced by Rhizobium loti and Bradyrhizobium sp. (Lotus) on Lotus pedunculatus

1985 ◽  
Vol 63 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Susan M. Wood ◽  
David B. Layzell ◽  
William Newcomb ◽  
Clive E. Pankhurst
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Morphometric Study ◽  
Polar Bodies ◽  
Rhizobium Loti ◽  
Bradyrhizobium Sp ◽  
Infected Cells ◽  
Peribacteroid Space ◽  
Lotus Pedunculatus

Effective root nodules formed on Lotus pedunculatus by Rhizobium loti NZP2037 and Bradyrhizobium sp. (Lotus) CC814s were examined by light and electron microscopy. NZP2037 nodules were larger than CC814s nodules as a result of a much thicker nodule cortex. The smaller CC814s nodules had a much larger infected zone and, consequently, larger volumes of infected cells, peribacteroid space, and host cytosol per nodule. As well, CC814s nodules demonstrated a significantly higher number of bacteria which typically contained prominent polar bodies and beta-polyhydroxybutyrate (PHB) granules. The bacteria of NZP2037 nodules lacked the polar bodies, but PHB deposits were occasionally observed. A correlated physiological study in which acetylene reduction was used to estimate nitrogen fixation showed CC814s nodules to be more active than NZP2037 nodules (Pankhurst, C. E., and D. B. Layzell. 1984. Physiol. Plant. 62(3) : 404–409.). This measured difference in nitrogen-fixing activity was considered due to the degree of infection and bacterial proliferation as well as differences in the carbon and nitrogen metabolism of the two nodule types. The significance of the structural observations and morphometric analyses and their relationship to differences in nitrogen fixation are discussed.

Effective and ineffective root nodules in Myrica faya

1976 ◽  
Vol 194 (1116) ◽  
pp. 285-293 ◽  
Keyword(s):  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Nodule Formation ◽  
Culture Solution ◽  
Myrica Gale ◽  
Main Site ◽  
Myrica Faya ◽  
Modern Methods ◽  
Infected Cells ◽  
Nodule Endophytes

In cross-inoculation trials, inocula containing the nodule endophytes of Myrica gale, M. cerifera, M. cordifolia and M. pilulifera respectively were applied to the roots of young plants of M. faya Ait. growing in nitrogen-free culture solution. All four inocula induced nodule formation, and except where the M. gale inoculum had been used the nodules were of effective type and enabled the plants bearing them to grow nearly as well as other M. faya plants associated with the normal endophyte. The nodules induced by the M. gale endophyte were very numerous, but remained small and fixed no significant amount of nitrogen, and were thus ineffective. Light and electron microscopy showed that in the effective nodules induced by the normal endophyte or by that of M. cordifolia , the endophyte was confined to a layer 1-2 cells deep near the middle of the nodule cortex, and that in respect of the width of the hyphae and their production of club-shaped internally subdivided vesicles, the endophytes resembled closely those in the nodules of the few other species of Myrica that have been studied by modern methods of microscopy. In ineffective nodules the disposition of the infected cells was unchanged, but within the cells only a sparse development of the endophyte was observed, and no vesicles were found. The finding that nodules lacking vesicles showed little or no fixation is consistent with other evidence that the vesicles normally produced by non-legume nodule endophytes are the main site of nitrogen fixation.

Morphological and biochemical changes in peanut nodules during photosynthate stress

1992 ◽  
Vol 38 (6) ◽  
pp. 526-533 ◽  
Author(s):  
A. B. M. Siddique ◽  
A. K. Bal
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Ultrastructural Level ◽  
Malate Synthase ◽  
Morphological Evidence ◽  
Lipid Bodies ◽  
Biochemical Status ◽  
Short Period ◽  
Infected Cells ◽  
Ultrastructural Damage

Nitrogen fixation in legume root nodules is believed to be supported by the supply of photosynthate of the current photoperiod. However, in peanut nodules, prolonged periods of darkness or detopping do not disrupt nitrogen fixation for at least 48 h. During this period, nodule oleosomes (lipid bodies) have been shown to decrease in number within the infected cells, and it has been suggested that lipids from oleosomes are mobilized to maintain the energy and carbon requirements of the nitrogen-fixing nodules. We present morphological evidence, at the ultrastructural level, for the utilization of oleosomes during photosynthate stress. The biochemical status of the nodule has also been assessed and correlated with ultrastructure. For comparison cowpea nodules were used that totally lacked oleosomes. In peanut nodules leghemoglobin and total protein remained unchanged along with integrated ultrastructure on nodule cells for 48 h, whereas in cowpea a decline in proteins with ultrastructural damage became apparent within a very short period of photosynthate stress. In peanut nodules empty or partially empty oleosomes were taken as evidence for their utilization during the stress period. Key words: N2 fixation, photosynthate stress, lipid bodies, catalase, malate synthase, peanut nodule, β-oxidation.

Symbiotic properties of Lotus pedunculitis root nodules induced by Rhizobium loti and Bradyrhizobium sp. (Lotus)

1987 ◽  
Vol 69 (3) ◽  
pp. 435-442 ◽  
Author(s):  
Carroll P. Vance ◽  
Paul H. Reibach ◽  
Clive E. Pankhurst
Keyword(s):  
Root Nodules ◽  
Rhizobium Loti ◽  
Bradyrhizobium Sp ◽  
Symbiotic Properties

Comparative morphology and flavolan content of Rhizobium loti induced effective and ineffective root nodules on Lotus species, Leuceana leucocephala, Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus

1987 ◽  
Vol 65 (12) ◽  
pp. 2676-2685 ◽  
Author(s):  
Clive E. Pankhurst ◽  
Douglas H. Hopcroft ◽  
William T. Jones
Keyword(s):  
Plasma Membrane ◽  
Root Nodules ◽  
Comparative Morphology ◽  
Lotus Corniculatus ◽  
Rhizobium Loti ◽  
Infection Threads ◽  
Membrane Bound ◽  
Lotus Pedunculatus ◽  
Ornithopus Sativus

The morphology of Rhizobium loti induced root nodules and the flavolan content of nodulated roots of several Lotus species, Leuceana leucocephala, Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus were examined. Rhizobium loti strain NZP2037 formed effective (Nod+Fix+) nodules on all legumes, but strain NZP2213 formed Nod+Fix+ nodules only on Lotus corniculatus var. cree and ineffective (Nod+Fix−) nodules on all other legumes. The Nod+Fix− nodules developed by NZP2213 showed morphologies ranging from the complete absence of bacteria within “tumour-like” structures to the development of nodules containing bacteria that were either not released or only incompletely released from infection threads. Within nodules formed by NZP2213 on Lotus corniculatus var. hirsutus and Carmichaelia flagelliformis the rhizobia had multiplied extensively within unwalled, plasma membrane bound, infection droplets. Flavolans rich in prodelphinidin, which is toxic towards NZP2213, were present in the roots of Lotus angustissimus, Lotus pedunculatus, Lotus subbiflorus, and Leuceana leucocephala, but only trace amounts of flavolan were found in the roots of Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus.

scholarly journals Proliferation of peroxisomes in pea root nodules - an influence of NaCI- or Hg2+- stress conditions

2011 ◽  
Vol 76 (4) ◽  
pp. 287-298 ◽  
Author(s):  
Wojciech Borucki
Keyword(s):  
Oxidative Stress ◽  
Electron Microscopy ◽  
Nitrogen Fixation ◽  
Pisum Sativum ◽  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Nitrogen Fixing ◽  
Morphometric Measurements ◽  
Meristematic Cells ◽  
Pea Root

Morphometric procedures were used to examine peroxisome number and di-stribution in pea (<em>Pisum sativum</em> L.) root nodules under NaCl (50 mM) or HgCl<sub>2</sub> (7.3 µM) treatment. Peroxisomes were visualized cytochemically in meristem, invasion zone and prefixing zone of pea root nodules by catalase (EC 1.11.1.6) activity. The observations using light and electron microscopy revealed that the peroxisomes were predominantly spherical in shape and showed catalase activity. In nitrogen fixation zone, catalase active peroxisomes were observed occasionally. Bacteroids of nitrogen fixing zone showed enhanced cata-lase activity probably as a response to higher level of oxidative stress. Fluorescence microscopy investigations revealed enhanced level of (homo)glutathione in prefixing and nitrogen-fixing zone of NaCl- and Hg<sup>2+</sup>treated nodules, which served as an indicator of antioxidative response. Morphometric measurements revealed that during differentiation of meristematic cells into central tissue (bacteroidal tissue) cells an increase in peroxisome number was observed in unstressed nodules. Peroxisomes located in meristem, invasion zone and prefixing zone of NaCl- and Hg<sup>2+</sup>-treated nodules outnumbered that in control nodules. A substantial enlargement of peroxisome profiles was detected in NaCl- and Hg<sup>2+</sup>treated nodules. Peroxisome divisions observed in meristematic and infection thread penetration zone were responsible for an increase in peroxisome number.

scholarly journals Enhanced Nitrogen Fixation and Competitiveness for Nodulation of Lotus pedunculatus by a Plasmid-cured Derivative of Rhizobium loti

Microbiology ◽  
1986 ◽  
Vol 132 (8) ◽  
pp. 2321-2328 ◽  
Author(s):  
C. E. Pankhurst ◽  
P. E. Macdonald ◽  
J. M. Reeves
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Loti ◽  
Lotus Pedunculatus

scholarly journals Mutation in the ntrR Gene, a Member of the vap Gene Family, Increases the Symbiotic Efficiency of Sinorhizobium meliloti

2001 ◽  
Vol 14 (7) ◽  
pp. 887-894 ◽  
Author(s):  
Boglárka Oláh ◽  
Erno Kiss ◽  
Zoltán Györgypál ◽  
Judit Borzi ◽  
Gyöngyi Cinege ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nifh Gene ◽  
Dry Weight ◽  
Nodule Occupancy ◽  
Gene Encoding ◽  
Symbiotic Efficiency ◽  
Host Interactions

In specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner Sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. Here, we report that a derivative of S. meliloti carrying a mutation in the chromosomal ntrR gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. The efficient nitrogen fixation is a result of the higher expression level of the nifH gene, encoding one of the subunits of the nitrogenase enzyme, and nifA, the transcriptional regulator of the nif operon. The ntrR gene, controlled negatively by its own product and positively by the symbiotic regulator syrM, is expressed in the same zone of nodules as the nif genes. As a result of the nitrogen-tolerant phenotype of the strain, the beneficial effect of the mutation on efficiency is not abolished in the presence of the exogenous nitrogen source. The ntrR mutant is highly competitive in nodule occupancy compared with the wild-type strain. Sequence analysis of the mutant region revealed a new cluster of genes, termed the “ntrPR operon,” which is highly homologous to a group of vap-related genes of various pathogenic bacteria that are presumably implicated in bacterium-host interactions. On the basis of its favorable properties, the strain is a good candidate for future agricultural utilization.

scholarly journals NITROGEN FIXATION BY EXCISED SOY BEAN ROOT NODULES

1954 ◽  
Vol 208 (1) ◽  
pp. 29-39
Author(s):  
M.H. Aprison ◽  
Wayne E. Magee ◽  
R.H. Burris
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Bean Root

The Role of Dryas Drummondii in Vegetation Development Following Ice Recession at Glacier Bay, Alaska, with Special Reference to Its Nitrogen Fixation by Root Nodules

1967 ◽  
Vol 55 (3) ◽  
pp. 793 ◽  
Author(s):  
D. B. Lawrence ◽  
R. E. Schoenike ◽  
A. Quispel ◽  
G. Bond
Keyword(s):  
Nitrogen Fixation ◽  
Special Reference ◽  
Root Nodules ◽  
Vegetation Development ◽  
Glacier Bay
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