Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants
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 chl...
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MDPI AG
2022-06-01
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| Series: | International Journal of Molecular Sciences |
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| author | Michael Moustakas Ilektra Sperdouli Ioannis-Dimosthenis S. Adamakis Julietta Moustaka Sumrunaz İşgören Begüm Şaş |
| author_facet | Michael Moustakas Ilektra Sperdouli Ioannis-Dimosthenis S. Adamakis Julietta Moustaka Sumrunaz İşgören Begüm Şaş |
| author_sort | Michael Moustakas |
| collection | DOAJ |
| description | 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 (<i>Solanum lycopersicum</i> 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 (q<i>p</i>), and the increased efficiency of open reaction centers (F<i>v</i>’/F<i>m</i>’). SA induced a decrease in chlorophyll content, resulting in a decrease in non-regulated energy dissipated in PSII (Φ<i><sub>NO</sub></i>) under high light (HL) treatment, suggesting a lower amount of triplet excited state chlorophyll (<sup>3</sup>Chl*) molecules available to produce singlet oxygen (<sup>1</sup>O<sub>2</sub>). 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 (H<sub>2</sub>O<sub>2</sub>), 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. |
| first_indexed | 2024-03-09T21:51:11Z |
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| id | doaj.art-b22924f374e94b1ab6366af5d13e4a98 |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T21:51:11Z |
| publishDate | 2022-06-01 |
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| spelling | doaj.art-b22924f374e94b1ab6366af5d13e4a982023-11-23T20:06:53ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-06-012313703810.3390/ijms23137038Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop PlantsMichael Moustakas0Ilektra Sperdouli1Ioannis-Dimosthenis S. Adamakis2Julietta Moustaka3Sumrunaz İşgören4Begüm Şaş5Department of Botany, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceInstitute of Plant Breeding and Genetic Resources, Hellenic Agricultural Organisation-Demeter (ELGO-Demeter), 57001 Thessaloniki, GreeceSection of Botany, Department of Biology, National and Kapodistrian University of Athens, 15784 Athens, GreeceDepartment of Botany, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceDepartment of Botany, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceDepartment of Botany, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceSalicylic 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 (<i>Solanum lycopersicum</i> 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 (q<i>p</i>), and the increased efficiency of open reaction centers (F<i>v</i>’/F<i>m</i>’). SA induced a decrease in chlorophyll content, resulting in a decrease in non-regulated energy dissipated in PSII (Φ<i><sub>NO</sub></i>) under high light (HL) treatment, suggesting a lower amount of triplet excited state chlorophyll (<sup>3</sup>Chl*) molecules available to produce singlet oxygen (<sup>1</sup>O<sub>2</sub>). 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 (H<sub>2</sub>O<sub>2</sub>), 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.https://www.mdpi.com/1422-0067/23/13/7038chlorophyll fluorescencelight reactionsreactive oxygen species (ROS)photoinhibitionphotodamagenon-photochemical quenching |
| spellingShingle | Michael Moustakas Ilektra Sperdouli Ioannis-Dimosthenis S. Adamakis Julietta Moustaka Sumrunaz İşgören Begüm Şaş Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants International Journal of Molecular Sciences chlorophyll fluorescence light reactions reactive oxygen species (ROS) photoinhibition photodamage non-photochemical quenching |
| title | Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants |
| title_full | Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants |
| title_fullStr | Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants |
| title_full_unstemmed | Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants |
| title_short | Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants |
| title_sort | harnessing the role of foliar applied salicylic acid in decreasing chlorophyll content to reassess photosystem ii photoprotection in crop plants |
| topic | chlorophyll fluorescence light reactions reactive oxygen species (ROS) photoinhibition photodamage non-photochemical quenching |
| url | https://www.mdpi.com/1422-0067/23/13/7038 |
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