Photosynthesis Research最新文献

{"title":"Molecular level insight into non-bilayer structure formation in thylakoid membranes: a molecular dynamics study.","authors":"Bence Fehér, Gergely Nagy, Győző Garab","doi":"10.1007/s11120-025-01156-3","DOIUrl":"10.1007/s11120-025-01156-3","url":null,"abstract":"<p><p>In oxygenic photosynthetic organisms, the light reactions are performed by protein complexes embedded in the lipid bilayer of thylakoid membranes (TMs). The organization of the bulk lipid molecules into bilayer structures provide optimal conditions for the build-up of the proton motive force (pmf) and its utilization for ATP synthesis. However, the lipid composition of TMs is dominated by the non-bilayer lipid species monogalactosyl diacylglycerol (MGDG), and functional plant TMs, besides the bilayer, contain large amounts of non-bilayer lipid phases. Bulk lipids have been shown to be associated with lumenal, stromal-side and marginal-region proteins and proposed to play roles in the self-assembly and photoprotection of the photosynthetic machinery. Furthermore, it has recently been pointed out that the generation and utilization of pmf for ATP synthesis according to the 'protet' or protonic charge transfer model Kell (Biochim Biophys Acta Bioenerg 1865(4):149504, 2024), requires high MGDG content Garab (Physiol Plant 177(2):e70230, 2025). In this study, to gain better insight into the structural and functional roles of MGDG, we employed all atom and coarse-grained molecular dynamics simulations to explore how temperature, hydration levels and varying MGDG concentrations affect the structural and dynamic properties of bilayer membranes constituted of plant thylakoid lipids. Our findings reveal that MGDG promotes increased membrane fluidity and dynamic fluctuations in membrane thickness. MGDG-rich stacked bilayers spontaneously formed inverted hexagonal phases; these transitions were enhanced at low hydration levels and at elevated but physiologically relevant temperatures. It can thus be inferred that MGDG plays important roles in heat and drought stress mechanisms.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"36"},"PeriodicalIF":2.9,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12158855/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144267031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diurnal light fitness of the C3 and C4 species from the genus Atriplex under control and drought conditions.","authors":"Reham M Nada, Abdel Hamid A Khedr, Mamdouh S Serag, Nesma R El-Qashlan, Gaber M Abogadallah","doi":"10.1007/s11120-025-01154-5","DOIUrl":"10.1007/s11120-025-01154-5","url":null,"abstract":"<p><p>The literature showed contradictory results regarding the acclimation of C3 and C4 photosynthesis to low light intensities. Atriplex halimus, A. nummularia (C4, NAD-ME), A. portulacoides and A. prostrata (C3) were exposed to three natural light intensities: full light (FL), medium light (ML) and low light (LL) under control or drought condition. Under control condition, in A. halimus and A. nummularia, photosynthetic rate (A) was proportionally linked to stomatal conductance (g_s). In A. halimus, A and gs peaked at 9:00 and 12:00 at FL only. However, A and gs peaked at 9:00 and 12:00 under FL and ML, respectively, in A. nummularia. The leakage of CO₂ could limit A in the C4 species under lower light intensities. A. halimus reduced g_s and A (a typical NAD-ME strategy) to cope with lower light intensities. However, A. nummularia optimized leaf anatomical features and PEPC/ Rubisco ratio to reduce CO₂ leakage, leading to improved g_s, A and biomass. In contrast, the increase in g_s reflected no increase in A, which could be attributed to the negative effect of low light on the electron transport system in the C3 species. Under drought condition, the performance of the C3 and C4 species was better at ML and LL than that at FL because of enhanced g_s and A. The present study concluded that the C4 species acclimated better to low light intensities than the C3 species. The acclimation of the C4 species was dependent on the species and the soil water content rather than the biochemical subtype.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"35"},"PeriodicalIF":2.9,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12158838/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144267030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The lumenal domain of Cyt b₅₅₉ interacting with extrinsic subunits is crucial for accumulation of functional photosystem II.","authors":"Ko Imaizumi, Shin-Ichi Arimura, Kentaro Ifuku","doi":"10.1007/s11120-025-01157-2","DOIUrl":"https://doi.org/10.1007/s11120-025-01157-2","url":null,"abstract":"<p><p>Cytochrome b₅₅₉ (Cyt b₅₅₉) is an essential component of the photosystem II (PSII) reaction center core. It consists of two subunits, PsbE and PsbF, which together coordinate a redox-active heme. While extensive studies have revealed the importance of Cyt b₅₅₉, its structural and functional roles are not fully understood. Previous studies have implied that the lumenal region of Cyt b₅₅₉, interacting with the PSII extrinsic subunit PsbP in green plant PSII, may have important roles. However, few studies have investigated its lumenal region. Here, we have focused on a well-conserved lumenal region of PsbE, which was found to interact with the N-terminal region of PsbP in green-lineage PSII (from green algae and land plants). In red-lineage PSII (from red algae and algae possessing red algal-derived plastids), very similar interactions were observed between the same lumenal region of PsbE and the N-terminal region of PsbQ'. We generated Arabidopsis thaliana mutants harboring mutations in the well-conserved lumenal region of PsbE through targeted base editing of the plastid genome by ptpTALECD. The mutations led to strong growth defects and extremely low F_v/F_m. This study suggests the importance of the lumenal regions of Cyt b₅₅₉, and gives insight into possible structural and functional compensation between the N-terminal regions of PsbP in green-lineage PSII and PsbQ' in red-lineage PSII.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"33"},"PeriodicalIF":2.9,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of cationic antiseptics on the vectorial electron and proton transfer in chromatophores of photosynthetic bacteria.","authors":"M D Mamedov, E P Lukashev, P P Knox, V Z Paschenko, L A Vitukhnovskya, A M Mamedova, A B Rubin","doi":"10.1007/s11120-025-01155-4","DOIUrl":"https://doi.org/10.1007/s11120-025-01155-4","url":null,"abstract":"<p><p>The effect of the cationic antiseptics octenidine and miramistin on electron transfer reactions in photosynthetic bacterial chromatophores of Cereibacter sphaeroides has been studied using direct electrometric and flash photolysis techniques. When the ubiquinone pool and cytochrome bc₁ complex were oxidized, the addition of octеnidine at a concentration of 100 µM completely inhibited the generation of transmembrane electric potential difference (Δψ) caused by protonation of the doubly reduced secondary quinone acceptor Q_B in the reaction center and, accordingly, vectorial charge transfer within the bc₁ complex in response to a second laser flash. The lack of an effect of octenidine and miramistin on the rapid rise of Δψ (τ < 0.1 µs) due to charge separation between the primary electron donor P₈₇₀ and the primary quinone acceptor Q_A was accompanied by an acceleration of Δψ decay kinetics over a period of ~ 10 ms in the presence of the former. The effect of miramistin was less pronounced. Overall, the data obtained by the two methods are qualitatively similar. The different effects of octanidine and miramistin are undoubtedly due to their structural features and may be related to their disordering influences on both the Q_B-binding site of the reaction center and the structure of the bilayer phospholipid membrane of chromatophores. These results are also important for understanding the molecular mechanisms of action of cationic antiseptics on both charge transfer reactions and thylakoid membrane integrity in oxygenic photosynthetic organisms.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"34"},"PeriodicalIF":2.9,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biochemical and phylogenetic analyses of light-harvesting complexes from Tetraselmis striata.","authors":"Yuma N Yamamoto, Takehiro Suzuki, Yoshifumi Ueno, Tatsuya Tomo, Naoshi Dohmae, Atsushi Takabayashi, Ryo Nagao","doi":"10.1007/s11120-025-01152-7","DOIUrl":"https://doi.org/10.1007/s11120-025-01152-7","url":null,"abstract":"<p><p>Oxygenic photosynthetic organisms employ light-harvesting complexes (LHCs) to capture solar energy and regulate excess excitation. Tetraselmis species belong to Chlorodendrophyceae, one of the earliest-diverging lineages within core Chlorophyta. While these organisms exhibit distinctive pigment compositions, their LHC organization and function remain largely uncharacterized. Here, we examined the biochemical and spectral properties of LHC, PSI-LHCI, and PSII-LHCII complexes from Tetraselmis striata NIES-1019. Pigment analysis identified loroxanthin derivatives, loroxanthin decenoate and loroxanthin dodecenoate, in all three complexes. Notably, these carotenoids are absent in Chlamydomonas reinhardtii and Ostreococcus tauri, implying a lineage-specific adaptation. Fluorescence spectra of PSII-LHCII and PSI-LHCI from T. striata exhibited distinct characteristics compared with their counterparts in C. reinhardtii and land plants, indicating differences in pigment organization. In contrast, LHC fluorescence properties closely resembled those of green-lineage organisms, suggesting conservation of chlorophyll-binding arrangements. Phylogenetic analyses revealed that T. striata possesses LHCBM-based LHCII trimers, consistent with other core Chlorophyta, but its PSI antenna composition diverges from that of these algae. Among LHCIs in the PSI outer belt, only LHCA5a was identified, whereas LHCA4a and LHCA6a were absent, implying structural divergence from C. reinhardtii. These findings provide insights into the evolution of LHCs in Chlorophyta and the distinct pigment-protein interactions underlying Tetraselmis light-harvesting strategies.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"32"},"PeriodicalIF":2.9,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144143340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonpigmented PsbR is involved in the integrity of excitation landscape in higher plant photosystem II, a case study in Arabidopsis thaliana and a mutant.","authors":"Dariusz M Niedzwiedzki, Rupal Singh Tomar, Nikki Cecil M Magdaong, Haijun Liu","doi":"10.1007/s11120-025-01153-6","DOIUrl":"https://doi.org/10.1007/s11120-025-01153-6","url":null,"abstract":"<p><p>PsbR is a nonpigmented 10 kDa protein in Photosystem II (PSII) in algae and plants. A recent structural study clarified its enigmatic structural location in a Photosystem II megacomplex that has baffled the community for more than four decades. Our current study interrogates whether absence of PsbR affects the overall dynamics of excitation energy migration within light harvesting complexes (LHC) and PSII super assemblies using highly-active PSII membrane particles, so-called BBY particles, isolated from a PsbR deletion mutant (ΔPsbR) of Arabidopsis thaliana. A femto-second (fs)-time-resolved transient absorption experimentation recorded at 77 K with selective excitation of Chl b which is exclusively present in LHCs enabled us to resolve the temporal differences in LHC→LHC and LHC→PSII excitation energy transfer steps. By applying specific target spectro-kinetic models to the transient absorption datasets, we demonstrated that the time constants of Chl a_LHC → Chl a_LHC excitation transfer significantly elongates in the ΔPsbR LHC-PSII particles, suggestive of the decreased aggregation level of photosynthetic proteins in the mutant. These findings highlight excitation energy transfer integrity in LHC-PSII assembly is not only determined by the pigmented light-harvesting complexes, but also synergistically by the nonpigmented PSII components. The disturbed integrity in dynamics of excitation energy transfer pathway within LHC-PSII supercomplex is discussed in the context of the altered LHC-PSII megacomplexes type I and II architectures which result from the absence of the PsbR protein in higher plant PSII.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"31"},"PeriodicalIF":2.9,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144128378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photosynthetic capacity and pigment distribution of a siphonous green alga, Dichotomosiphon tuberosus.","authors":"Soichiro Seki, Koichi Kobayashi, Ritsuko Fujii","doi":"10.1007/s11120-025-01148-3","DOIUrl":"10.1007/s11120-025-01148-3","url":null,"abstract":"<p><p>Dichotomosiphon tuberosus is one of the Bryopsidales, a siphonous, unicellular multinucleate ulvophyte. Bryopsidales typically occur in the ocean and contain unique carbonyl carotenoids siphonaxanthin (Sx) and its ester siphonein (Sn) in their major light-harvesting pigment-protein complexes, allowing them to utilize the green light available in the deep ocean for photosynthesis. However, unlike other Bryopsidales, D. tuberosus occurs in fresh water and is reported to contain Sn but not Sx. D. tuberosus inhabits deep lakes around the world, but in Okinawa, Japan, it inhabits very shallow waterways. Here, we measured the photosynthetic capacity of D. tuberosus collected from Okinawa waterway and compared it with another intertidal Bryopsidale Codium fragile. D. tuberosus had higher photosynthetic electron transport capacity and stronger non-photochemical quenching than C. fragile, consistent with the brighter growth environments for D. tuberosus than C. fragile. We also measured the absorption spectra and the pigment compositions within the photosynthetic pigment-protein complexes from D. tuberosus. Green light absorption of each complex in D. tuberosus was weaker than that in C. fragile. In contrast, Chl b absorption in LHCII was stronger in D. tuberosus than in C. fragile, whereas the opposite was true in photosystems. This implies that a large proportion of the irradiated energy is absorbed by LHCII complex and quenched more efficiently. Our results indicate that the photosynthetic capacity of D. tuberosus is further optimized for higher light environments compared with C. fragile.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"30"},"PeriodicalIF":2.9,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12095453/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144111508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating photosynthetic and chlorophyll fluorescence responses to light in peanut acclimated to elevated CO₂ and temperature.","authors":"Rajanna G Adireddy, Saseendran S Anapalli, Christopher D Delhom, Naveen Puppala, Krishna N Reddy","doi":"10.1007/s11120-025-01151-8","DOIUrl":"https://doi.org/10.1007/s11120-025-01151-8","url":null,"abstract":"<p><p>In plants, the photo-inhibitory effects of incident lights on the light-harvesting complexes are balanced by photoprotective mechanisms to maintain photosynthesis. With increasing air CO₂ concentrations and temperatures, the balance can tilt either way, with unpredictable consequences for biomass assimilated through photosynthesis. As such, it is critical to assess the photosynthetic responses of crop plants growing in future climates to light for developing strategies for sustaining food production. This study evaluated changes in photosynthetic and chlorophyll fluorescence responses to light intensities in peanuts (Arachis hypogaea L) acclimated to projected future climates by Global Circulation Models (GCM). The plants were grown in plant growth chambers under three climate conditions (CC): (1) ambient air [CO₂] and ambient temperature [Ta] (CC1), (2) [CO₂] at 570 ppm and Ta + 3⁰ C (CC2 climate possible in 2050), and (3) [CO₂] at 780 ppm and Ta + 5⁰C (CC3, climate possible in 2080). Plants growing under all three climates enhanced photosynthetic rates (A) with light intensities from 0 to 1500 µ mol m^- 2 s^- 1 but decreased afterward. Compared to CC1, plants growing under CC2 and CC3 reduced electron transport rates (ETR), A, and transpiration (Tr) between 48 and 190%, 52 and 65%, and 22 and 24%, respectively. Concurrently, the quantum efficiency of photosystem II (ФPS2) was reduced by 88-200% and photochemical quenching (qP) by 55-170%. Non-photochemical quenching increased with increasing light levels from 200 to 1500 µmol m⁻² s⁻¹ and decreased afterward. Results indicated the possibility of reduced photosynthetic efficiencies under CC2 and CC3, which would significantly reduce biomass production in future climates. Gaining insight into these impacts can help understand plant's ability to adapt and assist in developing adaptive strategies for sustainable peanut farming.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"29"},"PeriodicalIF":2.9,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144015871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing substrate water access through the O1 channel of Photosystem II by single site mutations and membrane inlet mass spectrometry.","authors":"A Orkun Aydin, Casper de Lichtenberg, Feiyan Liang, Jack Forsman, André T Graça, Petko Chernev, Shaochun Zhu, André Mateus, Ann Magnuson, Mun Hon Cheah, Wolfgang P Schröder, Felix Ho, Peter Lindblad, Richard J Debus, Fikret Mamedov, Johannes Messinger","doi":"10.1007/s11120-025-01147-4","DOIUrl":"https://doi.org/10.1007/s11120-025-01147-4","url":null,"abstract":"<p><p>Light-driven water oxidation by photosystem II sustains life on Earth by providing the electrons and protons for the reduction of CO₂ to carbohydrates and the molecular oxygen we breathe. The inorganic core of the oxygen evolving complex is made of the earth-abundant elements manganese, calcium and oxygen (Mn₄CaO₅ cluster), and is situated in a binding pocket that is connected to the aqueous surrounding via water-filled channels that allow water intake and proton egress. Recent serial crystallography and infrared spectroscopy studies performed with PSII isolated from Thermosynechococcus vestitus (T. vestitus) support that one of these channels, the O1 channel, facilitates water access to the Mn₄CaO₅ cluster during its S₂→S₃ and S₃→S₄→S₀ state transitions, while a subsequent CryoEM study concluded that this channel is blocked in the cyanobacterium Synechocystis sp. PCC 6803, questioning the role of the O1 channel in water delivery. Employing site-directed mutagenesis we modified the two O1 channel bottleneck residues D1-E329 and CP43-V410 (T. vestitus numbering) and probed water access and substrate exchange via time resolved membrane inlet mass spectrometry. Our data demonstrates that water reaches the Mn₄CaO₅ cluster via the O1 channel in both wildtype and mutant PSII. In addition, the detailed analysis provides functional insight into the intricate protein-water-cofactor network near the Mn₄CaO₅ cluster that includes the pentameric, near planar 'water wheel' of the O1 channel.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"28"},"PeriodicalIF":2.9,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12014804/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144011177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"UVR regulation of photoprotection in Phaeodactylum tricornutum (Bacillariophyceae): roles of light energy doses.","authors":"Herculano Cella, José Bonomi-Barufi, Camila Lisarb Velasquez Bastolla, Camila Nader, Carlos Yure Oliveira, Rafael Garcia Lopes, Jacó Joaquim Mattos, Paulo Antunes Horta Junior, Henrique Cesar Venâncio, Eva Regina de Oliveira Rodrigues, Marcelo Maraschin, Leonardo Rubi Rörig, Afonso Celso Dias Bainy, Maria Risoleta Freire Marques, Roberto Bianchini Derner","doi":"10.1007/s11120-025-01149-2","DOIUrl":"https://doi.org/10.1007/s11120-025-01149-2","url":null,"abstract":"<p><p>The ability of diatoms to adapt to variable light conditions such as photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) is crucial for their survival and ecological role. The study aimed to investigate how different doses of UVR regulate the photoprotection mechanism in Phaeodactylum tricornutum. Five treatments were established: Control (PAR only), PAR + UVR D_6h (17.5 W m^- 2, 6 h, 378 KJ m^- 2), PAR + UVR 2D_6h (35 W m^- 2, 6 h, 756 KJ m^- 2), PAR + UVR 2D_12h (17.5 W m^- 2, 12 h, 756 KJ m^- 2), and PAR + UVR 4D_12h (35 W m^- 2, 12 h, 1.512 KJ m^- 2). The growth of P. tricornutum was significantly affected by UVR doses, with a growth pattern of 42-55% below the control (PAR only). Increasing the UVR dose also had negative effects on photosynthesis parameters and the levels of chlorophyll-a and fucoxanthin. The de-epoxidation state showed a high rate in treatments subjected to higher UVR doses, promoting an attempt to activate cellular protection mechanisms. In the transcriptional genes related to the xanthophyll cycle, a reduction in transcript levels of ZEP1 and ZEP2 genes was observed in PAR + UVR treatments, including a reduction up to 75% at 72 h of exposure. Also, an increase in transcript levels of VDE and VDL1 genes was observed for treatments with the same UVR dose, reaching about 9-fold increase for the 2D_12h dose and 10-fold increase for the 2D_6h dose, both at 72 h, suggesting a modification in the cell's ability to respond to UVR light stress.</p>","PeriodicalId":20130,"journal":{"name":"Photosynthesis Research","volume":"163 3","pages":"27"},"PeriodicalIF":2.9,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144042640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}