Abstract
Photosystem II (PSII) functions were investigated in basil (Ocimum basilicum L.) plants sprayed with 1 mM salicylic acid (SA) under non-stress (NS) or mild drought-stress (MiDS) conditions. Under MiDS, SA-sprayed leaves retained significantly higher (+36%) chlorophyll content compared to NS, SA-sprayed leaves. PSII efficiency in SA-sprayed leaves under NS conditions, evaluated at both low light (LL, 200 μmol photons m−2 s−1) and high light (HL, 900 μmol photons m−2 s−1), increased significantly with a parallel significant decrease in the excitation pressure at PSII (1-qL) and the excess excitation energy (EXC). This enhancement of PSII efficiency under NS conditions was induced by the mechanism of non-photochemical quenching (NPQ) that reduced singlet oxygen (1O2) production, as indicated by the reduced quantum yield of non-regulated energy loss in PSII (ΦNO). Under MiDS, the thylakoid structure of water-sprayed leaves appeared slightly dilated, and the efficiency of PSII declined, compared to NS conditions. In contrast, the thylakoid structure of SA-sprayed leaves did not change under MiDS, while PSII functionality was retained, similar to NS plants at HL. This was due to the photoprotective heat dissipation by NPQ, which was sufficient to retain the same percentage of open PSII reaction centers (qp), as in NS conditions and HL. We suggest that the redox status of the plastoquinone pool (qp) under MiDS and HL initiated the acclimation response to MiDS in SA-sprayed leaves, which retained the same electron transport rate (ETR) with control plants. Foliar spray of SA could be considered as a method to improve PSII efficiency in basil plants under NS conditions, at both LL and HL, while under MiDS and HL conditions, basil plants could retain PSII efficiency similar to control plants.
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Claims 10
Claim · model-written summary
Under mild drought, salicylic-acid-sprayed basil leaves had 36% higher chlorophyll content than sprayed leaves without stress.
- Taxon
- basil
Ocimum basilicume1 - Treatment
- SA‐sprayede0
- Outcome
- chlorophyll contente0
- Direction
- highere0
- Value
- +36%e0
- Qualifier
- Under MiDSe0
- Comparator
- NS, SA‐sprayed leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under MiDS, SA‐sprayed leaves retained significantly higher (+36%) chlorophyll content compared to NS, SA‐sprayed leaves”
e1“basil (Ocimum basilicum L.) plants sprayed with 1 mM salicylic acid”
Claim · model-written summary
Salicylic acid under non-stress conditions significantly increased PSII efficiency at low and high light.
- Taxon
- basilOcimum basilicume1
- Treatment
- SA‐sprayede0
- Outcome
- PSII efficiencye0
- Direction
- increasede0
- Qualifier
- under NS conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PSII efficiency in SA‐sprayed leaves under NS conditions, evaluated at both low light (LL, 200 μmol photons m−2 s−1) and high light (HL, 900 μmol photons m−2 s−1), increased significantly”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
Salicylic acid under non-stress conditions significantly decreased excitation pressure and excess excitation energy.
- Taxon
- basilOcimum basilicume2
- Treatment
- SA‐sprayede1
- Outcome
- excitation pressure at PSII (1-qL) and the excess excitation energy (EXC)e0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant decrease in the excitation pressure at PSII (1-qL) and the excess excitation energy (EXC)”
e1“SA‐sprayed leaves under NS conditions”
e2“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
Non-photochemical quenching reduced singlet oxygen production in salicylic-acid-sprayed leaves under non-stress conditions.
- Taxon
- basilOcimum basilicume1
- Outcome
- singlet oxygen (1O2) productione0
- Direction
- reducede0
- Qualifier
- non‐photochemical quenching (NPQ)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“non‐photochemical quenching (NPQ) that reduced singlet oxygen (1O2) production”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
Water-sprayed basil leaves under mild drought had slightly dilated thylakoids and reduced PSII efficiency compared with non-stress conditions.
- Taxon
- basilOcimum basilicume1
- Treatment
- Under MiDSe0
- Outcome
- efficiency of PSIIe0
- Direction
- declinede0
- Qualifier
- thylakoid structure of water‐sprayed leaves appeared slightly dilatede0
- Comparator
- NS conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under MiDS, the thylakoid structure of water‐sprayed leaves appeared slightly dilated, and the efficiency of PSII declined, compared to NS conditions”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
Salicylic-acid-sprayed basil leaves retained thylakoid structure and PSII function under mild drought.
- Taxon
- basilOcimum basilicume1
- Treatment
- SA‐sprayede0
- Outcome
- PSII functionalitye0
- Direction
- retainede0
- Comparator
- NS plants at HLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the thylakoid structure of SA‐sprayed leaves did not change under MiDS, while PSII functionality was retained, similar to NS plants at HL”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
Under mild drought and high light, NPQ heat dissipation maintained the proportion of open PSII reaction centers.
- Taxon
- basilOcimum basilicume1
- Outcome
- percentage of open PSII reaction centers (qp)e0
- Direction
- retain the samee0
- Qualifier
- photoprotective heat dissipation by NPQe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“photoprotective heat dissipation by NPQ, which was sufficient to retain the same percentage of open PSII reaction centers (qp), as in NS conditions and HL”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
The authors suggest plastoquinone-pool redox status initiated mild-drought acclimation in sprayed leaves.
- Taxon
- basilOcimum basilicume1
- Outcome
- acclimation response to MiDSe0
- Qualifier
- redox status of the plastoquinone pool (qp)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“redox status of the plastoquinone pool (qp) under MiDS and HL initiated the acclimation response to MiDS in SA‐sprayed leaves”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
Salicylic-acid-sprayed leaves retained the same electron transport rate as controls under mild drought.
- Taxon
- basilOcimum basilicume1
- Treatment
- SA‐sprayede0
- Outcome
- electron transport rate (ETR)e0
- Direction
- retained the samee0
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SA‐sprayed leaves, which retained the same electron transport rate (ETR) with control plants”
e1“basil (Ocimum basilicum L.) plants”
Claim · model-written summary
The authors propose foliar salicylic acid spray to improve basil PSII efficiency under non-stress conditions.
- Taxon
- basilOcimum basilicume0
- Treatment
- Foliar spray of SAe0
- Outcome
- improve PSII efficiencye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Foliar spray of SA could be considered as a method to improve PSII efficiency in basil plants under NS conditions, at both LL and HL”
The same questions in other papers
drought · physiology: photosynthesis · Ocimum basilicum (basil)Results agree
6 papers in the same direction as this paper
- negative
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3 papers more in this group
See all 7 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.