Abstract
Melatonin is important in the protection of plants suffering various forms of abiotic stress. The molecular mechanisms underlying the melatonin-mediated protection of their photosynthetic machinery are not completely resolved. This study investigates the effects of exogenous melatonin applications on salt-induced damage to the light reaction components of the photosynthetic machinery of tomato seedlings. The results showed that melatonin pretreatments can help maintain growth and net photosynthetic rate (PN) under salt stress conditions. Pretreatment with melatonin increased the effective quantum yield of photosystem II (ΦPSII), the photochemical quenching coefficient (qP) and the proportion of PSII centers that are "open" (qL) under saline conditions. In this way, damage to the photosynthetic electron transport chain (PET) in photosystem II (PSII) was mitigated. In addition, melatonin pretreatment facilitated the repair of PSII by maintaining the availability of D1 protein that was otherwise reduced by salinity. The ROS levels and the gene expressions of the chloroplast TRXs and PRXs were also investigated. Salt stress resulted in increased levels of reactive oxygen species (ROS), which were mitigated by melatonin. In tomato leaves under salt stress, the expressions of PRXs and TRXf declined but the expressions of TRXm1/4 and TRXm2 increased. Melatonin pretreatment promoted the expression of TRXf and the abundances of TRXf and TRXm gene products but had no effects on the expressions of PRXs. In summary, melatonin improves the photosynthetic activities of tomato seedlings under salt stress. The mechanism could be that: (1) Melatonin controls ROS levels and prevents damaging elevations of ROS caused by salt stress. (2) Melatonin facilitates the recovery of PET and D1 protein synthesis, thus enhancing the tolerance of photosynthetic activities to salinity. (3) Melatonin induces the expression of TRXf and regulates the abundance of TRXf and TRXm gene products, which may facilitate repair of the light reaction parts of the photosynthetic machinery.
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Claims 11
Claim · model-written summary
Melatonin pretreatment helped maintain tomato seedling growth and net photosynthetic rate under salt stress.
- Taxon
- Tomato Seedlings
Solanum lycopersicumt0 - Treatment
- melatonin pretreatmentse0
- Outcome
- growth and net photosynthetic rate (PN)e0
- Direction
- maintaine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“melatonin pretreatments can help maintain growth and net photosynthetic rate (PN) under salt stress conditions.”
t0“Tomato Seedlings”
Claim · model-written summary
Melatonin pretreatment increased three PSII photochemical measures in saline conditions.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- Pretreatment with melatonine0
- Outcome
- effective quantum yield of photosystem II (ΦPSII), the photochemical quenching coefficient (qP) and the proportion of PSII centers that are "open" (qL)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pretreatment with melatonin increased the effective quantum yield of photosystem II (ΦPSII), the photochemical quenching coefficient (qP) and the proportion of PSII centers that are "open" (qL) under saline conditions.”
t0“Tomato Seedlings”
Claim · model-written summary
Melatonin mitigated salt damage to PSII photosynthetic electron transport.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- Pretreatment with melatonine1
- Outcome
- damage to the photosynthetic electron transport chain (PET) in photosystem II (PSII)e0
- Direction
- mitigatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“damage to the photosynthetic electron transport chain (PET) in photosystem II (PSII) was mitigated.”
e1“Pretreatment with melatonin”
t0“Tomato Seedlings”
Claim · model-written summary
Melatonin pretreatment maintained D1 protein availability for PSII repair despite salinity.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- melatonin pretreatmente0
- Gene
- D1 proteine0
- Outcome
- availability of D1 proteine0
- Direction
- maintaininge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“melatonin pretreatment facilitated the repair of PSII by maintaining the availability of D1 protein that was otherwise reduced by salinity.”
t0“Tomato Seedlings”
Claim · model-written summary
Salt stress increased reactive oxygen species levels.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- Salt stresse0
- Outcome
- levels of reactive oxygen species (ROS)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salt stress resulted in increased levels of reactive oxygen species (ROS)”
t0“Tomato Seedlings”
Claim · model-written summary
Melatonin mitigated salt-induced reactive oxygen species levels.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- melatonine0
- Outcome
- levels of reactive oxygen species (ROS)e0
- Direction
- mitigatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“levels of reactive oxygen species (ROS), which were mitigated by melatonin.”
t0“Tomato Seedlings”
Claim · model-written summary
Under salt stress, tomato leaf PRXs and TRXf expression declined.
- Taxon
- tomatoSolanum lycopersicume0
- Organ / stage
- leavese0
- Gene
- PRXs and TRXfe0
- Outcome
- expressions of PRXs and TRXfe0
- Direction
- declinede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In tomato leaves under salt stress, the expressions of PRXs and TRXf declined”
Claim · model-written summary
Under salt stress, tomato leaf TRXm1/4 and TRXm2 expression increased.
- Taxon
- tomatoSolanum lycopersicume0
- Organ / stage
- leavese0
- Gene
- TRXm1/4 and TRXm2e0
- Outcome
- expressions of TRXm1/4 and TRXm2e0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In tomato leaves under salt stress, the expressions of PRXs and TRXf declined but the expressions of TRXm1/4 and TRXm2 increased.”
Claim · model-written summary
Melatonin pretreatment promoted TRXf expression.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- Melatonin pretreatmente0
- Gene
- TRXfe0
- Outcome
- expression of TRXfe0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Melatonin pretreatment promoted the expression of TRXf”
t0“Tomato Seedlings”
Claim · model-written summary
Melatonin pretreatment promoted abundances of TRXf and TRXm gene products.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- Melatonin pretreatmente0
- Gene
- TRXf and TRXme0
- Outcome
- abundances of TRXf and TRXm gene productse0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Melatonin pretreatment promoted the expression of TRXf and the abundances of TRXf and TRXm gene products”
t0“Tomato Seedlings”
Claim · model-written summary
Melatonin pretreatment had no effect on PRXs expression.
- Taxon
- Tomato SeedlingsSolanum lycopersicumt0
- Treatment
- Melatonin pretreatmente0
- Gene
- PRXse0
- Outcome
- expressions of PRXse0
- Direction
- no effectse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Melatonin pretreatment promoted the expression of TRXf and the abundances of TRXf and TRXm gene products but had no effects on the expressions of PRXs.”
t0“Tomato Seedlings”
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