Abstract
The invasive properties of Azoarcus sp. strain BH72, an endorhizospheric isolate of Kallar grass, on gnotobiotically grown seedlings of Oryza sativa IR36 and Leptochloa fusca (L.) Kunth were studied. Additionally, Azoarcus spp. were localized in roots of field-grown Kallar grass. To facilitate localization and to assure identity of bacteria, genetically engineered microorganisms expressing beta-glucuronidase were also used as inocula. beta-Glucuronidase staining indicated that the apical region of the root behind the meristem was the most intensively colonized. Light and electron microscopy showed that strain BH72 penetrated the rhizoplane preferentially in the zones of elongation and differentiation and colonized the root interior inter- and intracellularly. In addition to the root cortex, stelar tissue was also colonized; bacteria were found in the xylem. No evidence was obtained that Azoarcus spp. could reside in living plant cells; rather, plant cells were apparently destroyed after bacteria had penetrated the cell wall. A common pathogenicity test on tobacco leaves provided no evidence that representative strains of Azoarcus spp. are phytopathogenic. Compared with the control, inoculation with strain BH72 significantly promoted growth of rice seedlings. This effect was reversed when the plant medium was supplemented with malate (0.2 g/liter). N2 fixation was apparently not involved, because the same response was obtained with a nifK mutant of strain BH72, which has a Nif- phenotype. Also, Western blot (immunoblot) analysis of protein extracts from rice seedlings gave no indication that nitrogenase was present. PCR and Western immunoblotting, using primers specific for eubacteria and antibodies recognizing type-specific antigens, respectively, indicated that strain BH72 could colonize rice plants systemically, probably mediated by longitudinal spreading through vessels.
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Claims 10
Claim · model-written summary
The root apical region behind the meristem was most intensely colonized.
- Taxon
- grassest0
- Interactor
- Azoarcus sp. strain BH72Azoarcus sp.t0symbiont
- Outcome
- the apical region of the root behind the meristem was the most intensively colonizede0
Not reportedDirection
Verbatim
e0“beta-Glucuronidase staining indicated that the apical region of the root behind the meristem was the most intensively colonized.”
t0“Azoarcus sp. strain BH72 in grasses”
Claim · model-written summary
Strain BH72 preferentially entered root elongation and differentiation zones and colonized root interiors.
- Taxon
- grassest0
- Interactor
- Azoarcus sp. strain BH72Azoarcus sp.t0symbiont
- Outcome
- penetrated the rhizoplane preferentially in the zones of elongation and differentiation and colonized the root interior inter- and intracellularlye0
Not reportedDirection
Verbatim
e0“strain BH72 penetrated the rhizoplane preferentially in the zones of elongation and differentiation and colonized the root interior inter- and intracellularly.”
t0“Azoarcus sp. strain BH72 in grasses”
Claim · model-written summary
Bacteria also colonized stelar tissue and were found in xylem.
- Taxon
- grassest0
- Interactor
- Azoarcus sp. strain BH72Azoarcus sp.t0symbiont
- Outcome
- stelar tissue was also colonized; bacteria were found in the xyleme0
Not reportedDirection
Verbatim
e0“In addition to the root cortex, stelar tissue was also colonized; bacteria were found in the xylem.”
t0“Azoarcus sp. strain BH72 in grasses”
Claim · model-written summary
Azoarcus showed no evidence of residence in living plant cells, while penetrated cells appeared destroyed.
- Taxon
- grassest0
- Outcome
- plant cells were apparently destroyed after bacteria had penetrated the cell walle0
Not reportedDirection
Verbatim
e0“No evidence was obtained that Azoarcus spp. could reside in living plant cells; rather, plant cells were apparently destroyed after bacteria had penetrated the cell wall.”
t0“Azoarcus sp. strain BH72 in grasses”
Claim · model-written summary
A pathogenicity test found no evidence that Azoarcus strains are phytopathogenic on tobacco leaves.
- Taxon
- tobacco
Nicotiana tabacume0 - Organ / stage
- leavese0
- Outcome
- no evidence that representative strains of Azoarcus spp. are phytopathogenice0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A common pathogenicity test on tobacco leaves provided no evidence that representative strains of Azoarcus spp. are phytopathogenic.”
Claim · model-written summary
BH72 inoculation significantly promoted rice seedling growth versus control.
- Taxon
- rice seedlings
Oryza sativae0 - Treatment
- inoculation with strain BH72e0
- Interactor
- strain BH72e0symbiont
- Outcome
- growth of rice seedlingse0
- Direction
- promotede0
- Comparator
- the controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with the control, inoculation with strain BH72 significantly promoted growth of rice seedlings.”
Claim · model-written summary
Adding malate reversed the BH72 growth promotion.
- Taxon
- rice seedlingsOryza sativae0
- Treatment
- supplemented with malate (0.2 g/liter)e0
- Interactor
- strain BH72e0symbiont
- Outcome
- growth of rice seedlingse0
- Direction
- reversede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with the control, inoculation with strain BH72 significantly promoted growth of rice seedlings. This effect was reversed when the plant medium was supplemented with malate (0.2 g/liter).”
t0“Azoarcus sp. strain BH72 in grasses”
Claim · model-written summary
The nifK mutant produced the same rice growth response, suggesting N2 fixation was uninvolved.
- Taxon
- Oryza sativa IR36Oryza sativat0
- Treatment
- nifK mutant of strain BH72e0
- Interactor
- strain BH72e0symbiont
- Gene
- nifKe0
- Outcome
- the same responsee0
- Direction
- samee0
- Comparator
- strain BH72e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N2 fixation was apparently not involved, because the same response was obtained with a nifK mutant of strain BH72, which has a Nif- phenotype.”
t0“Oryza sativa IR36”
Claim · model-written summary
Rice seedling protein extracts gave no indication of nitrogenase.
- Taxon
- rice seedlingsOryza sativae0
- Gene
- nitrogenasee0
- Outcome
- no indication that nitrogenase was presente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Western blot (immunoblot) analysis of protein extracts from rice seedlings gave no indication that nitrogenase was present.”
Claim · model-written summary
PCR and immunoblotting indicated systemic rice colonization by BH72, probably through vessels.
- Taxon
- rice plantsOryza sativae0
- Interactor
- strain BH72e0symbiont
- Outcome
- colonize rice plants systemicallye0
- Qualifier
- probably mediated by longitudinal spreading through vesselse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“indicated that strain BH72 could colonize rice plants systemically, probably mediated by longitudinal spreading through vessels.”
The same questions in other papers
malate · growth · Oryza sativa (rice)Positive and negative results
1 in the opposite direction
- positive
inoculation · growth · Oryza sativa (rice)Positive and negative results
361 papers in the same direction as this paper · 34 in the opposite direction · 3 reporting no difference from an alternative
- no effect
- positive
- positive
395 papers more in this group
See all 399 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.