Abstract
TWO TECHNIQUES WERE USED TO ASSESS THE BINDING OF RHIZOBIA TO CLOVER ROOTS: indirect counting after radiolabeling the bacteria and direct counting by using phase-contrast microscopy. Microscopic observations revealed a large variability in the number of bacteria associated with individual root hairs. This variability made unbiased counting by microscopy difficult. Systematic examination of all visible root hairs and "blind" counting of coded strains and treatments were adopted to minimize observer bias. The validity of the radiolabeling method was also examined in some detail. The reproducibility of results from this method was satisfactory. However, drawbacks of this method included its lack of sensitivity and its failure to distinguish between bacteria attached to mature root hairs, emerging root hairs, and undifferentiated epidermal cells. The method also failed to distinguish between individual bacteria and any aggregates that may be present. The ability of a number of chosen mutant strains of Rhizobium trifolii and their corresponding parent strains, as well as a number of nonhomologous strains, to bind to clover roots was assessed by using both of these methods. Our results gave no indication of specificity of R. trifolii binding to clover roots. 2-Deoxy-d-glucose did not appear to have a major inhibitory effect on the attachment of rhizobia to the host root, which suggests that lectin cross-bridging is not an obligatory step in the initiation of infection even though it may occur under some conditions. The presence or absence of the symbiotic plasmid was not correlated with bacterial adherence to the host plant root. Since host specificity functions are carried on this plasmid, our results suggest that binding of rhizobia to the legume root is not the basis of host specificity.
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Claims 9
Claim · model-written summary
Bacteria associated with individual clover root hairs varied largely in number.
- Taxon
- Trifolium repens
Trifolium repenst0 - Outcome
- number of bacteria associated with individual root hairse1
- Qualifier
- large variabilitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“Microscopic observations revealed a large variability in the number of bacteria associated with individual root hairs”
Claim · model-written summary
Reproducibility of results from the radiolabeling method was satisfactory.
- Taxon
- Trifolium repensTrifolium repenst0
- Outcome
- reproducibility of resultse2
- Value
- satisfactorye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e2“The reproducibility of results from this method was satisfactory”
Claim · model-written summary
The radiolabeling method had a lack of sensitivity and a failure to distinguish attached bacteria compared with direct counting by phase-contrast microscopy.
- Taxon
- Trifolium repensTrifolium repenst0
- Outcome
- lack of sensitivitye3
- Qualifier
- failure to distinguish between bacteria attached to mature root hairs, emerging root hairs, and undifferentiated epidermal cellse3
- Comparator
- direct counting by using phase-contrast microscopye4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e3“drawbacks of this method included its lack of sensitivity and its failure to distinguish between bacteria attached to mature root hairs, emerging root hairs, and undifferentiated epidermal cells”
e4“indirect counting after radiolabeling the bacteria and direct counting by using phase-contrast microscopy”
Claim · model-written summary
The method failed to distinguish between individual bacteria and aggregates.
- Taxon
- Trifolium repensTrifolium repenst0
- Outcome
- distinguish between individual bacteria and any aggregatese1
- Qualifier
- failed to distinguishe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“The method also failed to distinguish between individual bacteria and any aggregates that may be present”
Claim · model-written summary
Binding of R. trifolii to clover roots showed no indication of specificity.
- Taxon
- Trifolium repensTrifolium repenst0
- Interactor
- R. trifolii
Rhizobium leguminosarume1symbiont - Outcome
- specificity of R. trifolii binding to clover rootse1
- Qualifier
- no indicatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“Our results gave no indication of specificity of R. trifolii binding to clover roots”
Claim · model-written summary
2-Deoxy-d-glucose did not have a major inhibitory effect on rhizobial attachment to the clover root.
- Taxon
- Trifolium repensTrifolium repenst0
- Treatment
- 2-Deoxy-d-glucosee1
- Interactor
- rhizobiae1symbiont
- Outcome
- attachment of rhizobia to the host roote1
- Direction
- did not appear to have a major inhibitory effecte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“2-Deoxy-d-glucose did not appear to have a major inhibitory effect on the attachment of rhizobia to the host root”
Claim · model-written summary
Lectin cross-bridging is not an obligatory step in the initiation of infection, though it may occur under some conditions.
- Taxon
- Trifolium repensTrifolium repenst0
- Outcome
- initiation of infectione1
- Qualifier
- lectin cross-bridginge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“lectin cross-bridging is not an obligatory step in the initiation of infection”
Claim · model-written summary
The presence or absence of the symbiotic plasmid was not correlated with bacterial adherence to the host plant root.
- Taxon
- Trifolium repensTrifolium repenst0
- Treatment
- presence or absence of the symbiotic plasmide1
- Outcome
- bacterial adherence to the host plant roote1
- Direction
- was not correlatede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“The presence or absence of the symbiotic plasmid was not correlated with bacterial adherence to the host plant root”
Claim · model-written summary
Binding of rhizobia to the legume root is not the basis of host specificity.
- Taxon
- Trifolium repensTrifolium repenst0
- Outcome
- host specificitye1
- Qualifier
- binding of rhizobia to the legume roote1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Association of Rhizobium Strains with Roots of Trifolium repens”
e1“binding of rhizobia to the legume root is not the basis of host specificity”