OBSERVATIONS ON THE ROOT NODULES OF SHEPHERDIA

1957 ◽  
Vol 35 (3) ◽  
pp. 305-314 ◽  
Author(s):  
I. C. Gardner ◽  
G. Bond
Keyword(s):  
Nitrogen Content ◽  
Root Nodules ◽  
Solution Culture ◽  
Nodule Development ◽  
Culture Solution ◽  
Atmospheric Nitrogen ◽  
Related Genus ◽  
Combined Nitrogen ◽  
Ecological Importance ◽  
Shepherdia Canadensis

Nodulated plants of Shepherdia canadensis have been raised in solution culture and shown to be able to grow and increase their nitrogen content in a solution free of combined nitrogen. A fixation of atmospheric nitrogen by the nodules is indicated by the data obtained, and under the prevailing conditions it attained a maximum of about 8 mg. per plant during the first season of growth from seed. The nodule development was secured by the application of an inoculum prepared from nodules of the related genus Hippophaë. Nodulation occurred at pH 6 and 7 but not at pH 5; it was also suppressed by the presence of small amounts of combined nitrogen in the culture solution. The capacity of the nodulated Shepherdia plant to fix nitrogen is probably of ecological importance.

The Development and Significance of the Root Nodules of Casuarina

1957 ◽  
Vol 21 (3) ◽  
pp. 373-380 ◽  
Author(s):  
G. BOND
Keyword(s):  
Functional Significance ◽  
Root Nodules ◽  
Culture Solution ◽  
Atmospheric Nitrogen ◽  
Active Growth ◽  
Water Culture ◽  
Combined Nitrogen ◽  
Casuarina Cunninghamiana ◽  
Upward Growth

Abstract Young plants of Casuarina cunninghamiana and of C. equisetifolia growing in water culture developed macroscopic nodules in 26 to 35 days from inoculation, the nodulation being most successful at pH near to neutrality and falling off much more rapidly at lower pH than in other non-legume nodule-forming genera, confirming the distinctiveness of the Casuarina organism. The roots springing from the nodule lobes are shown to be characterized by upward growth and in this to resemble remarkably closely the corresponding roots of Myrica. Nodulated plants of Casuarina are able to grow vigorously in culture solution free of combined nitrogen, showing that fixation of atmospheric nitrogen occurs, amounting in C. cunninghamiana to 50 mg. per plant during 6 months of active growth. The evidence indicates that the fixation occurs in the nodules, and that these have exactly the same functional significance as those of legumes.

scholarly journals Some Observations on the Assimilation of Atmospheric Nitrogen by a Free Living Soil Organism.—Azotobacter Chroococcum of Beijerinck

1907 ◽  
Vol 2 (1) ◽  
pp. 35-51 ◽  
Author(s):  
S. F. Ashby
Keyword(s):  
Nitrogen Content ◽  
Total Nitrogen ◽  
Great Increase ◽  
Azotobacter Chroococcum ◽  
Atmospheric Nitrogen ◽  
Soil Organism ◽  
Free Living ◽  
Leguminous Plants ◽  
Combined Nitrogen ◽  
Free Element

Some years before the appearance of Hellriegel and Wilfarth's work on the sources of nitrogen of leguminous plants, and while the part played by atmospheric nitrogen in the nutrition of crops was under active discussion, Berthelot was making some exact observations on the behaviour of uncropped soils towards the free element. He found that when 50 kilograms of air-dry arable soil were exposed to the air and rain in a vessel for seven months a great increase in the nitrogen content could be observed; the total nitrogen of the original soil had increased from 50 grams to 63, or a gain of over 25 per cent, after allowing for the small amount of combined nitrogen brought down by rain; in another experiment where the soil had first been washed free from nitrates, a gain of 46 per cent, of nitrogen was proved. In many other cases, however, the gain was only from 10–15 per cent, of the original nitrogen present in the soil.

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.

Expression of Nodulin Genes During Nodule Development from Effective and Ineffective Root Nodules

1984 ◽  
pp. 579-586 ◽  
Author(s):  
Ton Bisseling ◽  
Francine Govers ◽  
Rita Wyndaele ◽  
Jan-Peter Nap ◽  
Jan-Willem Taanman ◽  
...  
Keyword(s):  
Root Nodules ◽  
Nodule Development ◽  
Nodulin Genes

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.

Diffusible factors from Frankia modify nodulation kinetics in Discaria trinervis, an intercellular root-infected actinorhizal symbiosis

2011 ◽  
Vol 38 (9) ◽  
pp. 662 ◽  
Author(s):  
Luciano Andrés Gabbarini ◽  
Luis Gabriel Wall
Keyword(s):  
Root Hair ◽  
Root Nodules ◽  
Root Hairs ◽  
Basic Structure ◽  
Peptide Bond ◽  
Nodule Development ◽  
Actinorhizal Symbiosis ◽  
Biochemical Characterisation ◽  
Clade 1 ◽  
Discaria Trinervis

Frankia BCU110501 induces nitrogen-fixing root nodules in Discaria trinervis (Gillies ex Hook. & Arn.) Reiche (Rhamnaceae) via intercellular colonisation, without root hair deformation. It produces diffusible factors (DFs) that might be involved in early interactions with the D. trinervis roots, playing a role in the nodulation process. The induction of root nodule development in actinorhizal symbiosis would depend on the concentration of factors produced by the bacteria and the plant. A detailed analysis of nodulation kinetics revealed that these DFs produce changes at the level of initial rate of nodulation and also in nodulation profile. Diluted Frankia BCU110501 inoculum could be activated in less than 96 h by DFs produced by Frankia BCU110501 cells that had been previously washed. Biochemical characterisation showed that Frankia BCU110501 DFs have a molecular weight of <12 kDa, are negatively charged at pH 7.0 and seem to contain a peptide bond necessary for their activity. Frankia BCU110501, belonging to Frankia Clade 3, does not induce nodules in Alnus acuminata H.B.K. ssp. acuminata but is able to deform root hairs, as do Frankia strains from Clade 1. The root hair deforming activity of Frankia BCU110501 DFs show the same biochemical characteristics of the DFs involved in nodulation of D. trinervis. These results suggest that Frankia symbiotic factors have a basic structure regardless of the infection pathway of the host plant.

scholarly journals Expression Analysis of PIN Genes in Root Tips and Nodules of Lotus japonicus

2019 ◽  
Vol 20 (2) ◽  
pp. 235 ◽  
Author(s):  
Izabela Sańko-Sawczenko ◽  
Dominika Dmitruk ◽  
Barbara Łotocka ◽  
Elżbieta Różańska ◽  
Weronika Czarnocka
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Quantitative Polymerase Chain Reaction ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Vascular Bundles ◽  
Root Tips ◽  
Gus Reporter ◽  
Gene Assay ◽  
Development And Differentiation

Auxins are postulated to be one of the pivotal factors in nodulation. However, their transporters in Lotus japonicus, the model species for the study of the development of determinate-type root nodules, have been scarcely described so far, and thus their role in nodulation has remained unknown. Our research is the first focusing on polar auxin transporters in L. japonicus. We analyzed and compared expression of PINs in 20 days post rhizobial inoculation (dpi) and 54 dpi root nodules of L. japonicus by real-time quantitative polymerase chain reaction (qPCR) along with the histochemical β-glucuronidase (GUS) reporter gene assay in transgenic hairy roots. The results indicate that LjPINs are essential during root nodule development since they are predominantly expressed in the primordia and young, developing nodules. However, along with differentiation, expression levels of several PINs decreased and occurred particularly in the nodule vascular bundles, especially in connection with the root’s stele. Moreover, our study demonstrated the importance of both polar auxin transport and auxin intracellular homeostasis during L. japonicus root nodule development and differentiation.

scholarly journals Root Nodules on Podocarpus Lawrencei and Their Ecological Significance

1964 ◽  
Vol 17 (1) ◽  
pp. 44 ◽  
Author(s):  
FJ Bergersen ◽  
AB Costin
Keyword(s):  
Nitrogen Fixation ◽  
Slow Growth ◽  
Root Nodules ◽  
General Structure ◽  
Intracellular Bacteria ◽  
Atmospheric Nitrogen ◽  
Ecological Significance ◽  
Anatomical Studies ◽  
Isotopic Method ◽  
Mode Of Development

Nodulated roots from P. lawrencei growing on a scree on Mt. Ginini, near Canberra, have been shown by the isotopic method to fix atmospheric nitrogen. The importance of this in a plant which is a pioneer of exposed, rocky situations is discussed. Although significant, the amount of nitrogen fixed by the detached nodulated roots wa�s low: this may have been due to the small proportion of nodules with active tissue, but it is also consistent with the slow growth observed for this species. The nodulated roots also evolved hydrogen u.s observed during nitrogen fixation by legume nodules. Anatomical studies of the Podocarpu8 nodules confirmed early accounts of their general structure and mode of development but the symbiont was clearly a non-septate filamentous organism: no intracellular bacteria were observed.

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