Abstract
Some plant growth promoting bacteria (PGPB) are enigmatic in enhancing plant growth in the face of increased metal accumulation in plants. Since most PGPB colonize the plant root epidermis, we hypothesized that PGPB confer tolerance to metals through changes in speciation at the root epidermis. We employed a novel combination of fluorophore-based confocal laser scanning microscopic imaging and synchrotron based microscopic X-ray fluorescence mapping with X-ray absorption spectroscopy to characterize bacterial localization, zinc (Zn) distribution and speciation in the roots of Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum. PGPB enhanced epidermal Zn sequestration relative to PGBP-free controls while the extent of endophytic accumulation depended on the colonization mode of each PGBP. Increased root accumulation of Zn and increased tolerance to Zn was associated predominantly with R. leguminosarum and was likely due to the coordination of Zn with cysteine-rich peptides in the root endodermis, suggesting enhanced synthesis of phytochelatins or glutathione. Our mechanistic model of enhanced Zn accumulation and detoxification in plants inoculated with R. leguminosarum has particular relevance to PGPB enhanced phytoremediation of soils contaminated through mining and oxidation of sulphur-bearing Zn minerals or engineered nanomaterials such as ZnS.
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Claims 5
Claim · model-written summary
Inoculation with Rhizobium leguminosarum increased root accumulation of Zn in Brassica juncea grown in Zn-contaminated media.
- Taxon
- Brassica juncea
Brassica junceae2 - Treatment
- Rhizobium leguminosarume2
- Interactor
- Rhizobium leguminosarum
Rhizobium leguminosarume2symbiont - Outcome
- root accumulation of Zne0
- Direction
- Increasede0
- Setting
- Zn contaminated mediae2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased root accumulation of Zn and increased tolerance to Zn was associated predominantly with R. leguminosarum”
e2“Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum”
Claim · model-written summary
Increased tolerance to Zn was associated predominantly with R. leguminosarum in Brassica juncea.
- Taxon
- Brassica junceaBrassica junceae2
- Interactor
- R. leguminosarumRhizobium leguminosarume0symbiont
- Outcome
- tolerance to Zne0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased root accumulation of Zn and increased tolerance to Zn was associated predominantly with R. leguminosarum”
e2“Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum”
Claim · model-written summary
PGPB enhanced epidermal Zn sequestration in Brassica juncea roots relative to PGPB-free controls.
- Taxon
- Brassica junceaBrassica junceae2
- Organ / stage
- epidermale1
- Treatment
- PGPBe1
- Outcome
- epidermal Zn sequestratione1
- Direction
- enhancede1
- Comparator
- PGBP-free controlse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“PGPB enhanced epidermal Zn sequestration relative to PGBP-free controls while the extent of endophytic accumulation depended on the colonization mode of each PGBP”
e2“Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum”
Claim · model-written summary
The extent of endophytic Zn accumulation depends on the colonization mode of each PGPB.
- Taxon
- Brassica junceaBrassica junceae2
- Treatment
- colonization modee1
- Outcome
- extent of endophytic accumulatione1
- Qualifier
- depended on the colonization mode of each PGBPe1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“PGPB enhanced epidermal Zn sequestration relative to PGBP-free controls while the extent of endophytic accumulation depended on the colonization mode of each PGBP”
e2“Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum”
Claim · model-written summary
Zn coordination with cysteine-rich peptides in root endodermis suggests enhanced synthesis of phytochelatins or glutathione in Brassica juncea.
- Taxon
- Brassica junceaBrassica junceae2
- Compound
- phytochelatins or glutathionee3
- Outcome
- coordination of Zne4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Brassica juncea grown in Zn contaminated media (400 mg kg(-1) Zn) with the endophytic Pseudomonas brassicacearum and rhizospheric Rhizobium leguminosarum”
e4“was likely due to the coordination of Zn with cysteine”
e3“suggesting enhanced synthesis of phytochelatins or glutathione”
The same questions in other papers
inoculation · nutrient: content · Brassica juncea (Indian mustard)Positive and negative results
22 papers in the same direction as this paper · 2 in the opposite direction
- no effect
- negative
- positive
21 papers more in this group
See all 25 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.