Abstract
Regions of the Rhizobium meliloti nodulation genes from the symbiotic plasmid were transferred to Agrobacterium tumefaciens and Rhizobium trifolii by conjugation. The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency. These were judged to be genuine nodules on the basis of cytological and developmental criteria. Like genuine alfalfa nodules, the nodules were initiated from divisions of the inner root cortical cells. They developed a distally positioned meristem and several peripheral vascular bundles. An endodermis separated the inner tissues of the nodule from the surrounding cortex. No infection threads were found to penetrate either root hairs or the nodule cells. Bacteria were found only in intercellular spaces. Thus, alfalfa nodules induced by A. tumefaciens and R. trifolii transconjugants carrying small nodulation clones of R. meliloti were completely devoid of intracellular bacteria. When these strains were inoculated onto white clover roots, small nodule-like protrusions developed that, when examined cytologically, were found to more closely resemble roots than nodules. Although the meristem was broadened and lacked a root cap, the protrusions had a central vascular bundle and other rootlike features. Our results suggest that morphogenesis of alfalfa root nodules can be uncoupled from infection thread formation. The genes encoded in the 8.7-kilobase nodulation fragment are sufficient in A. tumefaciens or R. trifolii backgrounds for nodule morphogenesis.
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Claims 14
Claim · model-written summary
A. tumefaciens transconjugants did not elicit alfalfa root hair curling.
- Taxon
- alfalfa
Medicago sativae0 - Treatment
- A. tumefaciens and R. trifolii transconjugantse0
- Interactor
- A. tumefaciens
Agrobacterium tumefaciense0symbiont - Outcome
- curling of alfalfa root hairse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency”
Claim · model-written summary
A. tumefaciens transconjugants induced alfalfa nodules at low frequency.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- A. tumefaciens and R. trifolii transconjugantse0
- Interactor
- A. tumefaciensAgrobacterium tumefaciense0symbiont
- Outcome
- nodule developmente0
- Qualifier
- at a low frequencye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency”
Claim · model-written summary
R. trifolii transconjugants did not elicit alfalfa root hair curling.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- A. tumefaciens and R. trifolii transconjugantse0
- Interactor
- R. trifolii
Rhizobium leguminosarume0symbiont - Outcome
- curling of alfalfa root hairse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency”
Claim · model-written summary
R. trifolii transconjugants induced alfalfa nodules at low frequency.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- A. tumefaciens and R. trifolii transconjugantse0
- Interactor
- R. trifoliiRhizobium leguminosarume0symbiont
- Outcome
- nodule developmente0
- Qualifier
- at a low frequencye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency”
Claim · model-written summary
The induced alfalfa nodules originated in inner root cortical cells.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- nodules were initiated from divisions of the inner root cortical cellse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nodules were initiated from divisions of the inner root cortical cells”
t0“alfalfa roots”
Claim · model-written summary
The induced alfalfa nodules formed a distal meristem and peripheral vascular bundles.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- distally positioned meristem and several peripheral vascular bundlese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They developed a distally positioned meristem and several peripheral vascular bundles”
t0“alfalfa roots”
Claim · model-written summary
An endodermis separated inner nodule tissue from the cortex.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- endodermis separated the inner tissues of the nodule from the surrounding cortexe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An endodermis separated the inner tissues of the nodule from the surrounding cortex”
t0“alfalfa roots”
Claim · model-written summary
No infection threads penetrated root hairs or nodule cells.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- No infection threads were found to penetrate either root hairs or the nodule cellse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No infection threads were found to penetrate either root hairs or the nodule cells”
t0“alfalfa roots”
Claim · model-written summary
Bacteria occurred only in intercellular spaces of induced nodules.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Bacteria were found only in intercellular spacese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Bacteria were found only in intercellular spaces”
t0“alfalfa roots”
Claim · model-written summary
Inoculated white clover roots formed small nodule-like protrusions.
- Taxon
- white clover
Trifolium repense0 - Treatment
- these strains were inoculatede0
- Outcome
- small nodule-like protrusions developede0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When these strains were inoculated onto white clover roots, small nodule-like protrusions developed”
Claim · model-written summary
White clover protrusions resembled roots more than nodules.
- Taxon
- white cloverTrifolium repense1
- Outcome
- more closely resemble roots than nodulese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when examined cytologically, were found to more closely resemble roots than nodules”
t0“alfalfa roots”
e1“When these strains were inoculated onto white clover roots, small nodule-like protrusions developed”
Claim · model-written summary
White clover protrusions had a broad meristem without a root cap and a central vascular bundle.
- Taxon
- white cloverTrifolium repense1
- Outcome
- meristem was broadened and lacked a root cape0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the meristem was broadened and lacked a root cap, the protrusions had a central vascular bundle and other rootlike features”
t0“alfalfa roots”
e1“When these strains were inoculated onto white clover roots, small nodule-like protrusions developed”
Claim · model-written summary
Alfalfa nodule morphogenesis can occur without infection thread formation.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- morphogenesis of alfalfa root nodulese0
- Qualifier
- uncoupled from infection thread formatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“morphogenesis of alfalfa root nodules can be uncoupled from infection thread formation”
Claim · model-written summary
The 8.7-kilobase nodulation fragment is sufficient for nodule morphogenesis in the two bacterial backgrounds.
- Taxon
- alfalfaMedicago sativat0
- Interactor
- A. tumefaciensAgrobacterium tumefaciense0symbiont
- Second interactor
- R. trifoliiRhizobium leguminosarume0symbiont
- Gene
- genes encoded in the 8.7-kilobase nodulation fragmente0
- Outcome
- nodule morphogenesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The genes encoded in the 8.7-kilobase nodulation fragment are sufficient in A. tumefaciens or R. trifolii backgrounds for nodule morphogenesis”
t0“alfalfa roots”
The same questions in other papers
Agrobacterium tumefaciens · symbiosis · Medicago sativa (alfalfa)Positive and negative results
1 in the opposite direction
- negative
inoculation · symbiosis · Trifolium repens (white clover)Positive and negative results
8 papers in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
- positive
6 papers more in this group
See all 10 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.