Abstract
Chromium (Cr) toxicity leads to the enhanced production of reactive oxygen species (ROS), which are extremely toxic to the plant and must be minimized to protect the plant from oxidative stress. The potential of plant-growth-promoting rhizobacteria (PGPR) and earthworms in plant growth and development has been extensively studied. The present study was aimed at investigating the effect of two PGPR ( Pseudomonas aeruginosa and Burkholderia gladioli ) along with earthworms ( Eisenia fetida ) on the antioxidant defense system in Brassica juncea seedlings under Cr stress. The Cr toxicity reduced the fresh and dry weights of seedlings, enhanced the levels of superoxide anion (O 2 • – ), hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), and electrolyte leakage (EL), which lead to membrane as well as the nuclear damage and reduced cellular viability in B. juncea seedlings. The activities of the antioxidant enzymes, viz ., superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase (APOX), glutathione peroxidase (GPOX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were increased; however, a reduction was observed in the activity of catalase (CAT) in the seedlings under Cr stress. Inoculation of the PGPR and the addition of earthworms enhanced the activities of all other antioxidant enzymes except GPOX, in which a reduction of the activity was observed. For total lipid- and water-soluble antioxidants and the non-enzymatic antioxidants, viz ., ascorbic acid and glutathione, an enhance accumulation was observed upon the inoculation with PGPR and earthworms. The supplementation of PGPR with earthworms (combined treatment) reduced both the reactive oxygen species (ROS) and the MDA content by modulating the defense system of the plant. The histochemical studies also corroborated that the combined application of PGPR and earthworms reduced O 2 • – , H 2 O 2 , lipid peroxidation, and membrane and nuclear damage and improved cell viability. The expression of key antioxidant enzyme genes, viz ., SOD, CAT, POD, APOX, GR, DHAR , and GST showed the upregulation of these genes at post-transcriptional level upon the combined treatment of the PGPR and earthworms, thereby corresponding to the improved plant biomass. However, a reduced expression of RBOH1 gene was noticed in seedlings supplemented under the effect of PGPR and earthworms grown under Cr stress. The results provided sufficient evidence regarding the role of PGPR and earthworms in the amelioration of Cr-induced oxidative stress in B. juncea .
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Claims 13
Claim · model-written summary
Chromium reduced seedling fresh and dry weights.
- Taxon
- Brassica juncea
Brassica junceat0 - Treatment
- Cr toxicitye0
- Outcome
- fresh and dry weights of seedlingse0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cr toxicity reduced the fresh and dry weights of seedlings”
t0“Brassica juncea”
Claim · model-written summary
Chromium raised superoxide, peroxide, MDA and electrolyte leakage.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- Chromiumt1
- Outcome
- levels of superoxide anion (O 2 • – ), hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), and electrolyte leakage (EL)e0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhanced the levels of superoxide anion (O 2 • – ), hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), and electrolyte leakage (EL)”
t0“Brassica juncea”
t1“Chromium”
Claim · model-written summary
Chromium caused membrane and nuclear damage and reduced cellular viability.
- Taxon
- B. junceaBrassica junceae0
- Treatment
- Chromiumt0
- Outcome
- membrane as well as the nuclear damage and reduced cellular viabilitye0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lead to membrane as well as the nuclear damage and reduced cellular viability in B. juncea seedlings”
t0“Chromium”
Claim · model-written summary
Chromium increased SOD, POD, APOX, GPOX, DHAR and GR activities.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- Cr stresse0
- Outcome
- activities of the antioxidant enzymese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activities of the antioxidant enzymes, viz ., superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase (APOX), glutathione peroxidase (GPOX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were increased; however, a reduction was observed in the activity of catalase (CAT) in the seedlings under Cr stress”
t0“Brassica juncea”
Claim · model-written summary
Chromium reduced catalase activity.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- Cr stresse0
- Outcome
- activity of catalase (CAT)e0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a reduction was observed in the activity of catalase (CAT) in the seedlings under Cr stress”
t0“Brassica juncea”
Claim · model-written summary
PGPR and earthworms enhanced antioxidant enzyme activities except GPOX.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- Inoculation of the PGPR and the addition of earthwormse0
- Outcome
- activities of all other antioxidant enzymes except GPOXe0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation of the PGPR and the addition of earthworms enhanced the activities of all other antioxidant enzymes except GPOX”
t0“Brassica juncea”
Claim · model-written summary
PGPR and earthworms increased soluble and nonenzymatic antioxidant accumulation.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- inoculation with PGPR and earthwormse0
- Outcome
- total lipid- and water-soluble antioxidants and the non-enzymatic antioxidantse0
- Direction
- enhancee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For total lipid- and water-soluble antioxidants and the non-enzymatic antioxidants, viz ., ascorbic acid and glutathione, an enhance accumulation was observed upon the inoculation with PGPR and earthworms”
t0“Brassica juncea”
Claim · model-written summary
Combined PGPR and earthworms reduced ROS and MDA.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- supplementation of PGPR with earthworms (combined treatment)e0
- Outcome
- reactive oxygen species (ROS) and the MDA contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The supplementation of PGPR with earthworms (combined treatment) reduced both the reactive oxygen species (ROS) and the MDA content”
t0“Brassica juncea”
Claim · model-written summary
Combined PGPR and earthworms reduced superoxide and peroxide staining.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- combined application of PGPR and earthwormse0
- Outcome
- O 2 • – , H 2 O 2 , lipid peroxidatione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“combined application of PGPR and earthworms reduced O 2 • – , H 2 O 2 , lipid peroxidation, and membrane and nuclear damage and improved cell viability”
t0“Brassica juncea”
Claim · model-written summary
Combined PGPR and earthworms reduced membrane and nuclear damage.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- combined application of PGPR and earthwormse0
- Outcome
- membrane and nuclear damagee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“combined application of PGPR and earthworms reduced O 2 • – , H 2 O 2 , lipid peroxidation, and membrane and nuclear damage”
t0“Brassica juncea”
Claim · model-written summary
Combined PGPR and earthworms improved cell viability.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- combined application of PGPR and earthwormse0
- Outcome
- cell viabilitye0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“combined application of PGPR and earthworms reduced O 2 • – , H 2 O 2 , lipid peroxidation, and membrane and nuclear damage and improved cell viability”
t0“Brassica juncea”
Claim · model-written summary
Combined PGPR and earthworms upregulated seven antioxidant genes.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- combined treatment of the PGPR and earthwormse0
- Outcome
- expression of key antioxidant enzyme genese0
- Direction
- upregulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The expression of key antioxidant enzyme genes, viz ., SOD, CAT, POD, APOX, GR, DHAR , and GST showed the upregulation of these genes at post-transcriptional level upon the combined treatment of the PGPR and earthworms”
t0“Brassica juncea”
Claim · model-written summary
PGPR and earthworms reduced RBOH1 expression under chromium stress.
- Taxon
- Brassica junceaBrassica junceat0
- Treatment
- PGPR and earthwormse0
- Gene
- RBOH1e0
- Outcome
- expression of RBOH1 genee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a reduced expression of RBOH1 gene was noticed in seedlings supplemented under the effect of PGPR and earthworms grown under Cr stress”
t0“Brassica juncea”
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