Abstract
Salicylic acid (SA), an essential plant hormone, has received much attention due to its role in modulating the adverse effects of biotic and abiotic stresses, acting as an antioxidant and plant growth regulator. However, its role in photosynthesis under non stress conditions is controversial. By chlorophyll fluorescence imaging analysis, we evaluated the consequences of foliar applied 1 mM SA on photosystem II (PSII) efficiency of tomato (Solanum lycopersicum L.) plants and estimated the reactive oxygen species (ROS) generation. Tomato leaves sprayed with 1 mM SA displayed lower chlorophyll content, but the absorbed light energy was preferentially converted into photochemical energy rather than dissipated as thermal energy by non-photochemical quenching (NPQ), indicating photoprotective effects provided by the foliar applied SA. This decreased NPQ, after 72 h treatment by 1 mM SA, resulted in an increased electron transport rate (ETR). The molecular mechanism by which the absorbed light energy was more efficiently directed to photochemistry in the SA treated leaves was the increased fraction of the open PSII reaction centers (qp), and the increased efficiency of open reaction centers (Fv’/Fm’). SA induced a decrease in chlorophyll content, resulting in a decrease in non-regulated energy dissipated in PSII (ΦNO) under high light (HL) treatment, suggesting a lower amount of triplet excited state chlorophyll (3Chl*) molecules available to produce singlet oxygen (1O2). Yet, the increased efficiency, compared to the control, of the oxygen evolving complex (OEC) on the donor side of PSII, associated with lower formation of hydrogen peroxide (H2O2), also contributed to less creation of ROS. We conclude that under non stress conditions, foliar applied SA decreased chlorophyll content and suppressed phototoxicity, offering PSII photoprotection; thus, it can be regarded as a mechanism that reduces photoinhibition and photodamage, improving PSII efficiency in crop plants.
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Claims 9
Claim · model-written summary
Salicylic acid lowered leaf chlorophyll content.
- Taxon
- Tomato
Solanum lycopersicume0 - Organ / stage
- leavese0
- Treatment
- 1 mM SAe0
- Outcome
- chlorophyll contente0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tomato leaves sprayed with 1 mM SA displayed lower chlorophyll content”
Claim · model-written summary
Absorbed energy was preferentially converted to photochemical energy rather than dissipated through NPQ.
- Taxon
- TomatoSolanum lycopersicume1
- Treatment
- 1 mM SAe1
- Outcome
- absorbed light energy was preferentially converted into photochemical energye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the absorbed light energy was preferentially converted into photochemical energy rather than dissipated as thermal energy by non-photochemical quenching (NPQ)”
e1“Tomato leaves sprayed with 1 mM SA”
Claim · model-written summary
Nonphotochemical quenching decreased after 72 hours of salicylic acid treatment.
- Taxon
- TomatoSolanum lycopersicume1
- Treatment
- 1 mM SAe0
- Outcome
- NPQe0
- Direction
- decreasede0
- Qualifier
- after 72 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This decreased NPQ, after 72 h treatment by 1 mM SA”
e1“Tomato leaves”
Claim · model-written summary
Electron transport rate increased after treatment.
- Taxon
- TomatoSolanum lycopersicume2
- Treatment
- 1 mM SAe1
- Outcome
- electron transport rate (ETR)e0
- Direction
- increasede0
- Qualifier
- after 72 he1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulted in an increased electron transport rate (ETR)”
e1“after 72 h treatment by 1 mM SA”
e2“Tomato leaves”
Claim · model-written summary
Open PSII reaction center fraction increased in treated leaves.
- Taxon
- TomatoSolanum lycopersicume2
- Treatment
- SAe1
- Outcome
- fraction of the open PSII reaction centers (qp)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased fraction of the open PSII reaction centers (qp)”
e1“in the SA treated leaves”
e2“Tomato leaves”
Claim · model-written summary
Efficiency of open reaction centers increased.
- Taxon
- TomatoSolanum lycopersicume2
- Treatment
- SAe1
- Outcome
- efficiency of open reaction centers (Fv’/Fm’)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased efficiency of open reaction centers (Fv’/Fm’)”
e1“in the SA treated leaves”
e2“Tomato leaves”
Claim · model-written summary
Nonregulated PSII energy dissipation decreased under high light.
- Taxon
- TomatoSolanum lycopersicume1
- Treatment
- SAe0
- Outcome
- non-regulated energy dissipated in PSII (ΦNO)e0
- Direction
- a decreasee0
- Qualifier
- under high light (HL) treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SA induced a decrease in chlorophyll content, resulting in a decrease in non-regulated energy dissipated in PSII (ΦNO) under high light (HL) treatment”
e1“Tomato leaves”
Claim · model-written summary
Oxygen evolving complex efficiency increased relative to control.
- Taxon
- TomatoSolanum lycopersicume1
- Treatment
- 1 mM SAe1
- Outcome
- efficiency, compared to the control, of the oxygen evolving complex (OEC)e0
- Direction
- increasede0
- Comparator
- the controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased efficiency, compared to the control, of the oxygen evolving complex (OEC) on the donor side of PSII”
e1“Tomato leaves sprayed with 1 mM SA”
Claim · model-written summary
Hydrogen peroxide formation was lower with increased oxygen evolving complex efficiency.
- Taxon
- TomatoSolanum lycopersicume2
- Outcome
- formation of hydrogen peroxide (H2O2)e0
- Direction
- lowere0
- Qualifier
- increased efficiency, compared to the control, of the oxygen evolving complex (OEC)e1
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“associated with lower formation of hydrogen peroxide (H2O2)”
e1“increased efficiency, compared to the control, of the oxygen evolving complex (OEC)”
e2“Tomato leaves”
The same questions in other papers
salicylic acid · control · Solanum lycopersicum (tomato)Positive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
- positive
1 paper more in this group
See all 5 papers →salicylic acid · physiology: photosynthesis · Solanum lycopersicum (tomato)Results agree
14 papers in the same direction as this paper
- positive
- positive
- positive
11 papers more in this group
See all 15 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.