Sinorhizobium meliloti in Australian soils: population studies of the root-nodule bacteria for species of Medicago in soils of the Eyre Peninsula, South Australia

2001 ◽  
Vol 41 (6) ◽  
pp. 753 ◽  
Author(s):  
J. Brockwell
Keyword(s):  
Soil Ph ◽  
Soil Type ◽  
Sinorhizobium Meliloti ◽  
Root Nodule ◽  
South Australia ◽  
Farming Systems ◽  
Annual Rainfall ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Large Populations

Populations of Sinorhizobium meliloti(formerly Rhizobium meliloti — the root-nodule bacteria for Medicago) from soils at 32 sites on the Eyre Peninsula, South Australia, were enumerated and evaluated for nitrogen-fixing effectiveness in association with Medicago laciniata, M. littoralis, M. polymorpha, M. rugosa, M. tornata and M. truncatula. These symbiotic values were related to physical features of the environment, viz. soil type, soil reaction, mean annual rainfall, and the presence or absence and frequency of occurrence of sown and naturalised annual species of Medicago (medics). Large populations of S. meliloti (ranging from 270 to 460000 per gram of soil) were detected in 28 of the 29 soils where medics occurred. One or more species of medic were found in 29 of the 32 soils examined. The other 3 soils were relatively moist and acidic in reaction with a mean soil pH (CaCl 2 ) of 5.5. It could be inferred that the presence of populations of S. meliloti was dependent on the occurrence of species of Medicago. Other features of the environment had no impact on the size of S. melilotipopulations, except insofar as they influenced the occurrence of medics. All populations of S. meliloti were effective in nitrogen fixation for M. littoralis and M truncatula, the 2 species most commonly sown as legume components of the cereal–pasture farming systems of the Eyre Peninsula. Effectiveness of populations of S. meliloti for M. polymorpha, M. rugosa and M. tornata was significantly greater (P<0.05) in soils where M. polymorpha occurred than where it did not. Otherwise, the symbiotic capacity of the root-nodule bacteria was not influenced by soil type, soil pH, rainfall or the presence or absence of particular medics. There are many indications that medic productivity on the Eyre Peninsula is in decline with detrimental consequences for the nitrogen economy of the farming systems. The almost universal occurrence in soils of the Eyre Peninsula of large populations of S. meliloti that were effective for M. littoralis and M. truncatula indicated that, whatever the reasons for ‘medic decline’, the condition is not attributable to inadequacies of the naturally occurring populations of root-nodule bacteria.

scholarly journals pyd Genes of Rhizobium sp. Strain TAL1145 Are Required for Degradation of 3-Hydroxy-4-Pyridone, an Aromatic Intermediate in Mimosine Metabolism

2005 ◽  
Vol 187 (13) ◽  
pp. 4480-4487 ◽  
Author(s):  
Jonathan D. Awaya ◽  
Paul M. Fox ◽  
Dulal Borthakur
Keyword(s):  
Abc Transporter ◽  
Bradyrhizobium Japonicum ◽  
Sinorhizobium Meliloti ◽  
Root Nodule ◽  
Structural Genes ◽  
Nodule Bacteria ◽  
Mesorhizobium Loti ◽  
Root Nodule Bacteria ◽  
Low Levels ◽  
Rhizobium Sp

ABSTRACT Rhizobium sp. strain TAL1145 degrades the Leucaena toxin mimosine and its degradation product 3-hydroxy-4-pyridone (HP). The aim of this investigation is to characterize the Rhizobium genes for HP degradation and transport. These genes were localized by subcloning and mutagenesis on a previously isolated cosmid, pUHR263, containing mid genes of TAL1145 required for mimosine degradation. Two structural genes, pydA and pydB, encoding a metacleavage dioxygenase and a hydrolase, respectively, are required for degradation of HP, and three genes, pydC, pydD, and pydE, encoding proteins of an ABC transporter, are involved in the uptake of HP by TAL1145. These genes are induced by HP, although both pydA and pydB show low levels of expression without HP. pydA and pydB are cotranscribed, while pydC, pydD, and pydE are each transcribed from separate promoters. PydA and PydB show no homology with other dioxygenases and hydrolases in Sinorhizobium meliloti, Mesorhizobium loti, and Bradyrhizobium japonicum. Among various root nodule bacteria, the ability to degrade mimosine or HP is unique to some Leucaena-nodulating Rhizobium strains.

scholarly journals Diversity and numbers of root-nodule bacteria (rhizobia) in Polish soils

2011 ◽  
Vol 74 (1) ◽  
pp. 83-86 ◽  
Author(s):  
Stefan Martyniuk ◽  
Jadwiga Oroń ◽  
Maria Martyniuk
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Plant Infection ◽  
Physical And Chemical ◽  
And Chemical Properties

Using a sand pouch-plant infection method, populations of several species of root-nodule bacteria (rhizobia) were enumerated in eighty soils collected throughout Poland. <em>Rhizobium leguminosarum</em> bv. <em>viciae</em> (symbionts of pea, faba bean, vetch) and <em>R. leguminosarum</em> bv. <em>trifolii</em> (symbionts of clover) were detected in 77 and 76 soils, respectively. Most of these soils contained moderate and high numbers of these species of the rhizobia. Symbionts of beans, <em>R. leguminosarum</em> bv.<em> phaseoli</em>, were assessed in 76 soils; of this number 15 soils had no detectable populations of bean rhizobia and in 40 soils high or moderate numbers of these bacteria were found. <em>Bradyrhizobium</em> sp. (<em>Lupinus</em>), root-nodule bacteria of lupine and serradella, were absent in 19 soils, out of 80 tested, and 34 soils were colonised by high or moderate populations of bradyrhizobia. <em>Sinorhizobium meliloti</em>, rhizobia nodulating alfalfa, were sparse in the examined soils; with 56 soil containing no detectable numbers of <em>S. meliloti</em> and only 6 soils harbouring high or moderate populations of this species. The estimated numbers of the rhizobia in the studied soils were also related to some physical and chemical properties of these soils.

scholarly journals Draft Genome Sequence of Sinorhizobium meliloti Strain AK170

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Olga A. Baturina ◽  
Victoria S. Muntyan ◽  
Maria E. Cherkasova ◽  
Alla S. Saksaganskaya ◽  
Nikolay I. Dzuybenko ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Sinorhizobium Meliloti ◽  
Root Nodule ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Symbiotic Relationship ◽  
Nodule Bacteria ◽  
Content Type ◽  
Root Nodule Bacteria ◽  
Meliloti Strain

Root nodule bacteria of Sinorhizobium meliloti species live in a symbiotic relationship with alfalfa plants. We report here the draft genome sequence of S. meliloti strain AK170, recovered from nodules of Medicago orthoceras (Kar.

Functional Specificity of the nifA Gene Product within the Group of Root Nodule Bacteria

Microbiology ◽  
2021 ◽  
Vol 90 (4) ◽  
pp. 481-488
Author(s):  
A. A. Vladimirova ◽  
R. S. Gumenko ◽  
E. S. Akimova ◽  
Al. Kh. Baymiev ◽  
An. Kh. Baymiev
Keyword(s):  
Gene Product ◽  
Root Nodule ◽  
Nodule Bacteria ◽  
Functional Specificity ◽  
Root Nodule Bacteria ◽  
Nifa Gene

scholarly journals Quantitative evaluation of acidity tolerance of root nodule bacteria

1999 ◽  
Vol 30 (3) ◽  
pp. 203-208 ◽  
Author(s):  
Luiz Antonio de Oliveira ◽  
Hélio Paracaima de Magalhães
Keyword(s):  
Root Nodule ◽  
Maximum Growth ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Soil Persistence ◽  
Statistical Precision ◽  
Visible Growth ◽  
Selection For ◽  
Growth Scores ◽  
Selection Of

Quantification of acidity tolerance in the laboratory may be the first step in rhizobial strain selection for the Amazon region. The present method evaluated rhizobia in Petri dishes with YMA medium at pH 6.5 (control) and 4.5, using scores of 1.0 (sensitive, "no visible" growth) to 4.0 (tolerant, maximum growth). Growth evaluations were done at 6, 9, 12, 15 and 18 day periods. This method permits preliminary selection of root nodule bacteria from Amazonian soils with statistical precision. Among the 31 rhizobia strains initially tested, the INPA strains 048, 078, and 671 presented scores of 4.0 at both pHs after 9 days of growth. Strain analyses using a less rigorous criterion (growth scores higher than 3.0) included in this highly tolerant group the INPA strains 511, 565, 576, 632, 649, and 658, which grew on the most diluted zone (zone 4) after 9 days. Tolerant strains still must be tested for nitrogen fixation effectiveness, competitiveness for nodule sites, and soil persistence before their recommendation as inoculants.

Application of molecular techniques to studies in Rhizobium ecology: a review

2001 ◽  
Vol 41 (3) ◽  
pp. 299 ◽  
Author(s):  
J. E. Thies ◽  
E. M. Holmes ◽  
A. Vachot
Keyword(s):  
Root Nodule ◽  
Molecular Techniques ◽  
Nodule Bacteria ◽  
Bacterial Genomes ◽  
Root Nodule Bacteria ◽  
Bacterial Signaling ◽  
Field Environment ◽  
Background Population ◽  
Insight Into ◽  
Made In

The symbiosis between legumes and their specific root-nodule bacteria, rhizobia, has been employed to improve agricultural productivity for most of the 20th century. During this time, great advances have been made in our knowledge of both plant and bacterial genomes, the biochemistry of the symbiosis, plant and bacterial signaling and the measurement of nitrogen fixation. However, knowledge of the ecology of the bacterial symbiont has lagged behind, largely due to a lack of practical techniques that can be used to monitor and assess the performance of these bacteria in the field. Most techniques developed in the last few decades have relied on somehow ‘marking’ individual strains to allow us to follow their fate in the field environment. Such techniques, while providing knowledge of the success or failure of specific strains in a range of environments, have not allowed insight into the nature of the pre-existing rhizobial populations in these sites, nor the interaction between marked strains and the background population. The advent of molecular techniques has revolutionised the study of Rhizobium ecology by allowing us to follow the flux of a variety of ecotypes within a particular site and to examine how introduced rhizobia interact with a genetically diverse background. In addition, molecular techniques have increased our understanding of how individual strains and populations of root-nodule bacteria respond to changes in the environment and how genetic diversity evolves in field sites over time. This review focuses on recently developed molecular techniques that hold promise for continuing to develop our understanding of Rhizobium ecology and how these can be used to address a range of applied problems to yield new insights into rhizobial life in soil and as legume symbionts.

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