Abstract
Salt stress inhibits plant growth by disturbing plant intrinsic physiology. The application of exogenous plant growth regulators to improve the plant tolerance against salt stress has become one of the promising approaches to promote plant growth in saline environment. Eugenol (4-allyl-2- methoxyphenol) is the main ingredient in clove oil and it is known for its strong antioxidant and anti-microbial activities. Eugenol also has the ability of inhibiting several plant pathogens, implying the potential use of eugenol as an environmental friendly agrichemical. However, little is known about the possible role of eugenol in the regulation of plant tolerance against abiotic stress. Therefore, here we investigated the effectiveness of phytochemical eugenol in promoting salt tolerance in tobacco seedlings through physiological, histochemical, and biochemical method. The seedling roots were exposed to NaCl solution in the presence or absence of eugenol. Salt stress inhibited seedling growth, but eugenol supplementation effectively attenuated its effects in a dose-dependent manner, with an optimal effect at 20 µM. ROS (reactive oxygen species) accumulation was found in seedlings upon salt stress which was further resulted in the amelioration of lipid peroxidation, loss of membrane integrity, and cell death in salt-treated seedlings. Addition of eugenol highly suppressed ROS accumulation and reduced lipid peroxidation generation. Both enzymatic and non-enzymatic antioxidative systems were activated by eugenol treatment. AsA/DHA and GSH/GSSG were also enhanced upon eugenol treatment, which helped maintain redox homeostasis upon salinity. Eugenol treatment resulted in an increase in the content of osmoprotectants (e.g. proline, soluble sugar and starch) in salt-treated seedlings. Na + levels decreased significantly in seedlings upon eugenol exposure. This may result from the upregulation of the expression of two ionic transporter genes, SOS1 (salt-hypersensitive 1) and NHX1 (Na + /H + anti-transporter 1). Hierarchical cluster combined correlation analysis uncovered that eugenol induced salt tolerance was mediated by redox homeostasis and maintaining ionic balance in tobacco seedlings. This work reveals that eugenol plays a crucial role in regulating plant resistant physiology. This may extend its biological function as a novel biostimulant and opens up new possibilities for improving crop productivity in the saline agricultural environment.
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Claims 10
Claim · model-written summary
Salt stress inhibited tobacco seedling growth.
- Taxon
- tobacco
Nicotiana tabacumt0 - Treatment
- Salt stresse0
- Outcome
- seedling growthe0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salt stress inhibited seedling growth”
t0“tobacco seedlings”
Claim · model-written summary
Eugenol supplementation attenuated the salt-stress effects on tobacco seedlings in a dose-dependent manner, with an optimal effect at 20 µM.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- eugenol supplementatione1
- Outcome
- its effectse1
- Direction
- attenuatede1
- Value
- 20 µMe1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“eugenol supplementation effectively attenuated its effects in a dose-dependent manner, with an optimal effect at 20 µM”
t0“tobacco seedlings”
Claim · model-written summary
ROS accumulated in tobacco seedlings under salt stress.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- salt stresse2
- Outcome
- ROS (reactive oxygen species) accumulatione2
- Direction
- accumulatione2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“ROS (reactive oxygen species) accumulation was found in seedlings upon salt stress”
t0“tobacco seedlings”
Claim · model-written summary
Eugenol suppressed ROS accumulation and reduced lipid peroxidation in salt-treated tobacco seedlings.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Addition of eugenole3
- Outcome
- ROS accumulation and reduced lipid peroxidation generatione3
- Direction
- suppressede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Addition of eugenol highly suppressed ROS accumulation and reduced lipid peroxidation generation”
t0“tobacco seedlings”
Claim · model-written summary
Both enzymatic and non-enzymatic antioxidative systems were activated by eugenol treatment.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- eugenol treatmente4
- Outcome
- enzymatic and non-enzymatic antioxidative systemse4
- Direction
- activatede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“Both enzymatic and non-enzymatic antioxidative systems were activated by eugenol treatment”
t0“tobacco seedlings”
Claim · model-written summary
AsA/DHA and GSH/GSSG ratios were enhanced by eugenol treatment under salinity.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- eugenol treatmente5
- Outcome
- AsA/DHA and GSH/GSSGe5
- Direction
- enhancede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“AsA/DHA and GSH/GSSG were also enhanced upon eugenol treatment”
t0“tobacco seedlings”
Claim · model-written summary
Eugenol treatment increased the content of osmoprotectants (proline, soluble sugar, starch) in salt-treated seedlings.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- Eugenol treatmente6
- Outcome
- content of osmoprotectantse6
- Direction
- increasee6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Eugenol treatment resulted in an increase in the content of osmoprotectants (e.g. proline, soluble sugar and starch) in salt-treated seedlings”
t0“tobacco seedlings”
Claim · model-written summary
Na+ levels decreased significantly in seedlings upon eugenol exposure.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- eugenol exposuree7
- Outcome
- Na + levelse7
- Direction
- decreasede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Na + levels decreased significantly in seedlings upon eugenol exposure”
t0“tobacco seedlings”
Claim · model-written summary
The decrease in Na+ may result from upregulated expression of the ionic transporter genes SOS1 and NHX1.
- Taxon
- tobaccoNicotiana tabacumt0
- Gene
- SOS1 (salt-hypersensitive 1) and NHX1e0
- Outcome
- upregulation of the expression of two ionic transporter genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the upregulation of the expression of two ionic transporter genes, SOS1 (salt-hypersensitive 1) and NHX1 (Na + /H + anti-transporter 1)”
t0“tobacco seedlings”
Claim · model-written summary
Eugenol-induced salt tolerance was mediated by redox homeostasis and maintaining ionic balance in tobacco seedlings.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- eugenole1
- Outcome
- salt tolerancee1
- Qualifier
- redox homeostasis and maintaining ionic balancee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“eugenol induced salt tolerance was mediated by redox homeostasis and maintaining ionic balance in tobacco seedlings”
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