58 research outputs found
Linear dichroism and circular dichroism in photosynthesis research
The efficiency of photosynthetic light energy conversion depends largely on the molecular architecture of the photosynthetic membranes. Linear- and circular-dichroism (LD and CD) studies have contributed significantly to our knowledge of the molecular organization of pigment systems at different levels of complexity, in pigment–protein complexes, supercomplexes, and their macroassemblies, as well as in entire membranes and membrane systems. Many examples show that LD and CD data are in good agreement with structural data; hence, these spectroscopic tools serve as the basis for linking the structure of photosynthetic pigment–protein complexes to steady-state and time-resolved spectroscopy. They are also indispensable for identifying conformations and interactions in native environments, and for monitoring reorganizations during photosynthetic functions, and are important in characterizing reconstituted and artificially constructed systems. This educational review explains, in simple terms, the basic physical principles, and theory and practice of LD and CD spectroscopies and of some related quantities in the areas of differential polarization spectroscopy and microscopy
24-Epibrassinolide Pre-Treatment Modifies Cold-Induced Photosynthetic Acclimation Mechanisms and Phytohormone Response of Perennial Ryegrass in Cultivar-Dependent Manner
Lipid Interacting Regions in Phosphate Stress Glycosyltransferase atDGD2 from Arabidopsis thaliana
Hepatoprotective effect of Quercetin supplementation against Acrylamide-induced DNA damage in wistar rats
An Internal Ribosome Entry Site Directs Translation of the 39-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity
[EN] Pelargonium flower break virus (PFBV, genus Carmovirus) has a single-stranded positive-sense genomic RNA (gRNA) which contains five ORFs. The two 59-proximal ORFs encode the replicases, two internal ORFs encode movement proteins, and the 39-proximal ORF encodes a polypeptide (p37) which plays a dual role as capsid protein and as suppressor of RNA silencing. Like other members of family Tombusviridae, carmoviruses express ORFs that are not 59-proximal from subgenomic RNAs. However, in one case, corresponding to Hisbiscus chlorotic ringspot virus, it has been reported that the 39-proximal gene can be translated from the gRNA through an internal ribosome entry site (IRES). Here we show that PFBV also holds an IRES that mediates production of p37 from the gRNA, raising the question of whether this translation strategy may be conserved in the genus. The PFBV IRES was functional both in vitro and in vivo and either in the viral context or when inserted into synthetic bicistronic constructs. Through deletion and mutagenesis studies we have found that the IRES is contained within a 80 nt segment and have identified some structural traits that influence IRES function. Interestingly, mutations that diminish IRES activity strongly reduced the infectivity of the virus while the progress of the infection was favoured by mutations potentiating such activity. These results support the biological significance of the IRES-driven p37 translation and suggest that production of the silencing suppressor from the gRNA might allow the virus to early counteract the defence response of the host, thus facilitating pathogen multiplication and spread.This research was supported by grants BFU2006-11230 and BFU2009-11699 from the Spanish Ministerio de Ciencia e Innovacion (MICINN) and by grants ACOM/2006/210 and ACOMP/2009/040 (to CH) and GVPRE/2008/121 (to OF-M) from the Generalitat Valenciana. The latter was the recipient of an I3P postdoctoral contract from the Spanish Consejo Superior de Investigaciones Cientificas and an additional contract from MICINN. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Fernandez Miragall, O.; Hernandez Fort, C. (2011). An Internal Ribosome Entry Site Directs Translation of the 39-Gene from Pelargonium Flower Break Virus Genomic RNA: Implications for Infectivity. PLoS ONE. 6(7):22617-22617. https://doi.org/10.1371/journal.pone.0022617S226172261767Gallie, D. R. (1996). Translational control of cellular and viral mRNAs. Plant Molecular Biology, 32(1-2), 145-158. doi:10.1007/bf00039381Kozak, M. (2002). Pushing the limits of the scanning mechanism for initiation of translation. Gene, 299(1-2), 1-34. doi:10.1016/s0378-1119(02)01056-9Sachs, A. B., Sarnow, P., & Hentze, M. W. (1997). Starting at the Beginning, Middle, and End: Translation Initiation in Eukaryotes. Cell, 89(6), 831-838. doi:10.1016/s0092-8674(00)80268-8Kozak, M. (1992). Regulation of Translation in Eukaryotic Systems. Annual Review of Cell Biology, 8(1), 197-225. doi:10.1146/annurev.cb.08.110192.001213Sonenberg, N., & Hinnebusch, A. G. (2009). Regulation of Translation Initiation in Eukaryotes: Mechanisms and Biological Targets. Cell, 136(4), 731-745. doi:10.1016/j.cell.2009.01.042F�tterer, J., & Hohn, T. (1996). Translation in plants-rules and exceptions. Plant Molecular Biology, 32(1-2), 159-189. doi:10.1007/bf00039382Gale, M., Tan, S.-L., & Katze, M. G. (2000). Translational Control of Viral Gene Expression in Eukaryotes. Microbiology and Molecular Biology Reviews, 64(2), 239-280. doi:10.1128/mmbr.64.2.239-280.2000Kozak, M. (2001). Constraints on reinitiation of translation in mammals. Nucleic Acids Research, 29(24), 5226-5232. doi:10.1093/nar/29.24.5226Pelletier, J., & Sonenberg, N. (1988). Internal initiation of translation of eukaryotic mRNA directed by a sequence derived from poliovirus RNA. Nature, 334(6180), 320-325. doi:10.1038/334320a0Mokrejš, M., Mašek, T., Vopálenský, V., Hlubuček, P., Delbos, P., & Pospíšek, M. (2009). IRESite—a tool for the examination of viral and cellular internal ribosome entry sites. Nucleic Acids Research, 38(suppl_1), D131-D136. doi:10.1093/nar/gkp981Basso, J., Dallaire, P., Charest, P. J., Devantier, Y., & Laliberte, J.-F. (1994). Evidence for an Internal Ribosome Entry Site Within the 5’ Non-translated Region of Turnip Mosaic Potyvirus RNA. Journal of General Virology, 75(11), 3157-3165. doi:10.1099/0022-1317-75-11-3157Levis, C., & Astier-Manifacier, S. (1993). The 5′ untranslated region of PVY RNA, even located in an internal position, enables initiation of translation. Virus Genes, 7(4), 367-379. doi:10.1007/bf01703392Karetnikov, A., & Lehto, K. (2007). The RNA2 5’ leader of Blackcurrant reversion virus mediates efficient in vivo translation through an internal ribosomal entry site mechanism. Journal of General Virology, 88(1), 286-297. doi:10.1099/vir.0.82307-0Ivanov, P. A., Karpova, O. V., Skulachev, M. V., Tomashevskaya, O. L., Rodionova, N. P., Dorokhov, Y. L., & Atabekov, J. G. (1997). A Tobamovirus Genome That Contains an Internal Ribosome Entry Site Functionalin Vitro. Virology, 232(1), 32-43. doi:10.1006/viro.1997.8525Skulachev, M. V., Ivanov, P. A., Karpova, O. V., Korpela, T., Rodionova, N. P., Dorokhov, Y. L., & Atabekov, J. G. (1999). Internal Initiation of Translation Directed by the 5′-Untranslated Region of the Tobamovirus Subgenomic RNA I2. Virology, 263(1), 139-154. doi:10.1006/viro.1999.9928Jaag, H. M., Kawchuk, L., Rohde, W., Fischer, R., Emans, N., & Prufer, D. (2003). An unusual internal ribosomal entry site of inverted symmetry directs expression of a potato leafroll polerovirus replication-associated protein. Proceedings of the National Academy of Sciences, 100(15), 8939-8944. doi:10.1073/pnas.1332697100Balvay, L., Rifo, R. S., Ricci, E. P., Decimo, D., & Ohlmann, T. (2009). Structural and functional diversity of viral IRESes. Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 1789(9-10), 542-557. doi:10.1016/j.bbagrm.2009.07.005Kneller, E. L. P., Rakotondrafara, A. M., & Miller, W. A. (2006). Cap-independent translation of plant viral RNAs. Virus Research, 119(1), 63-75. doi:10.1016/j.virusres.2005.10.010Rico, P., & Hern�ndez, C. (2004). Complete nucleotide sequence and genome organization of Pelargonium flower break virus. Archives of Virology, 149(3), 641-651. doi:10.1007/s00705-003-0231-5Martinez-Turino, S., & Hernandez, C. (2010). Identification and characterization of RNA-binding activity in the ORF1-encoded replicase protein of Pelargonium flower break virus. Journal of General Virology, 91(12), 3075-3084. doi:10.1099/vir.0.023093-0Martínez-Turiño, S., & Hernández, C. (2011). A membrane-associated movement protein of Pelargonium flower break virus shows RNA-binding activity and contains a biologically relevant leucine zipper-like motif. Virology, 413(2), 310-319. doi:10.1016/j.virol.2011.03.001Martinez-Turino, S., & Hernandez, C. (2009). Inhibition of RNA silencing by the coat protein of Pelargonium flower break virus: distinctions from closely related suppressors. Journal of General Virology, 90(2), 519-525. doi:10.1099/vir.0.006098-0Rico, P., & Hernández, C. (2009). Characterization of the subgenomic RNAs produced by Pelargonium flower break virus: Identification of two novel RNAs species. Virus Research, 142(1-2), 100-107. doi:10.1016/j.virusres.2009.01.018Koh, D. C.-Y., Wong, S.-M., & Liu, D. X. (2003). Synergism of the 3′-Untranslated Region and an Internal Ribosome Entry Site Differentially Enhances the Translation of a Plant Virus Coat Protein. Journal of Biological Chemistry, 278(23), 20565-20573. doi:10.1074/jbc.m210212200Hellen, C. U. T. (2001). Internal ribosome entry sites in eukaryotic mRNA molecules. Genes & Development, 15(13), 1593-1612. doi:10.1101/gad.891101Martínez-Salas, E. (1999). Internal ribosome entry site biology and its use in expression vectors. Current Opinion in Biotechnology, 10(5), 458-464. doi:10.1016/s0958-1669(99)00010-5Dobrikova, E., Florez, P., Bradrick, S., & Gromeier, M. (2003). Activity of a type 1 picornavirus internal ribosomal entry site is determined by sequences within the 3’ nontranslated region. Proceedings of the National Academy of Sciences, 100(25), 15125-15130. doi:10.1073/pnas.2436464100Belsham, G. J. (2009). Divergent picornavirus IRES elements. Virus Research, 139(2), 183-192. doi:10.1016/j.virusres.2008.07.001Fernández-Miragall, O., Quinto, S. L. de, & Martínez-Salas, E. (2009). Relevance of RNA structure for the activity of picornavirus IRES elements. Virus Research, 139(2), 172-182. doi:10.1016/j.virusres.2008.07.009Pestova, T. V., Kolupaeva, V. G., Lomakin, I. B., Pilipenko, E. V., Shatsky, I. N., Agol, V. I., & Hellen, C. U. T. (2001). Molecular mechanisms of translation initiation in eukaryotes. Proceedings of the National Academy of Sciences, 98(13), 7029-7036. doi:10.1073/pnas.111145798FERNANDEZ-MIRAGALL, O. (2003). Structural organization of a viral IRES depends on the integrity of the GNRA motif. RNA, 9(11), 1333-1344. doi:10.1261/rna.5950603ROBERTSON, M. E. M., SEAMONS, R. A., & BELSHAM, G. J. (1999). A selection system for functional internal ribosome entry site (IRES) elements: Analysis of the requirement for a conserved GNRA tetraloop in the encephalomyocarditis virus IRES. RNA, 5(9), 1167-1179. doi:10.1017/s1355838299990301Dorokhov, Y. L., Skulachev, M. V., Ivanov, P. A., Zvereva, S. D., Tjulkina, L. G., Merits, A., … Atabekov, J. G. (2002). Polypurine (A)-rich sequences promote cross-kingdom conservation of internal ribosome entry. Proceedings of the National Academy of Sciences, 99(8), 5301-5306. doi:10.1073/pnas.082107599Xia, X., & Holcik, M. (2009). Strong Eukaryotic IRESs Have Weak Secondary Structure. PLoS ONE, 4(1), e4136. doi:10.1371/journal.pone.0004136Lu, J., Zhang, J., Wang, X., Jiang, H., Liu, C., & Hu, Y. (2006). In vitro and in vivo identification of structural and sequence elements in the 5’ untranslated region of Ectropis obliqua picorna-like virus required for internal initiation. Journal of General Virology, 87(12), 3667-3677. doi:10.1099/vir.0.82090-0Yang, L. J., Hidaka, M., Sonoda, J., Masaki, H., & Uozumi, T. (1997). Mutational Analysis of the Potato Virus Y 5′ Untranslated Region for Alteration in Translational Enhancement in Tobacco Protoplasts. Bioscience, Biotechnology, and Biochemistry, 61(12), 2131-2133. doi:10.1271/bbb.61.2131BERGAMINI, G., PREISS, T., & HENTZE, M. W. (2000). Picornavirus IRESes and the poly(A) tail jointly promote cap-independent translation in a mammalian cell-free system. RNA, 6(12), 1781-1790. doi:10.1017/s1355838200001679Bradrick, S. S. (2006). The hepatitis C virus 3’-untranslated region or a poly(A) tract promote efficient translation subsequent to the initiation phase. Nucleic Acids Research, 34(4), 1293-1303. doi:10.1093/nar/gkl019Lopez de Quinto, S. (2002). IRES-driven translation is stimulated separately by the FMDV 3’-NCR and poly(A) sequences. Nucleic Acids Research, 30(20), 4398-4405. doi:10.1093/nar/gkf569Song, Y., Friebe, P., Tzima, E., Junemann, C., Bartenschlager, R., & Niepmann, M. (2006). The Hepatitis C Virus RNA 3’-Untranslated Region Strongly Enhances Translation Directed by the Internal Ribosome Entry Site. Journal of Virology, 80(23), 11579-11588. doi:10.1128/jvi.00675-06Koh, D. C.-Y., Liu, D. X., & Wong, S.-M. (2002). A Six-Nucleotide Segment within the 3’ Untranslated Region of Hibiscus Chlorotic Ringspot Virus Plays an Essential Role in Translational Enhancement. Journal of Virology, 76(3), 1144-1153. doi:10.1128/jvi.76.3.1144-1153.2002Stupina, V. A., Meskauskas, A., McCormack, J. C., Yingling, Y. G., Shapiro, B. A., Dinman, J. D., & Simon, A. E. (2008). The 3’ proximal translational enhancer of Turnip crinkle virus binds to 60S ribosomal subunits. RNA, 14(11), 2379-2393. doi:10.1261/rna.1227808Truniger, V., Nieto, C., González-Ibeas, D., & Aranda, M. (2008). Mechanism of plant eIF4E-mediated resistance against a Carmovirus (Tombusviridae): cap-independent translation of a viral RNA controlledin cisby an (a)virulence determinant. The Plant Journal, 56(5), 716-727. doi:10.1111/j.1365-313x.2008.03630.xMiller, W. A., Wang, Z., & Treder, K. (2007). The amazing diversity of cap-independent translation elements in the 3′-untranslated regions of plant viral RNAs. Biochemical Society Transactions, 35(6), 1629-1633. doi:10.1042/bst0351629Miller, W. A., & White, K. A. (2006). Long-Distance RNA-RNA Interactions in Plant Virus Gene Expression and Replication. Annual Review of Phytopathology, 44(1), 447-467. doi:10.1146/annurev.phyto.44.070505.143353Koh, D. C.-Y., Wang, X., Wong, S.-M., & Liu, D. X. (2006). Translation initiation at an upstream CUG codon regulates the expression of Hibiscus chlorotic ringspot virus coat protein. Virus Research, 122(1-2), 35-44. doi:10.1016/j.virusres.2006.06.008Castaño, A., Ruiz, L., & Hernández, C. (2009). Insights into the translational regulation of biologically active open reading frames of Pelargonium line pattern virus. Virology, 386(2), 417-426. doi:10.1016/j.virol.2009.01.017Fraser, C. S., & Doudna, J. A. (2006). Structural and mechanistic insights into hepatitis C viral translation initiation. Nature Reviews Microbiology, 5(1), 29-38. doi:10.1038/nrmicro1558LÓPEZ-LASTRA, M., RIVAS, A., & BARRÍA, M. I. (2005). Protein synthesis in eukaryotes: The growing biological relevance of cap-independent translation initiation. Biological Research, 38(2-3). doi:10.4067/s0716-97602005000200003Pacheco, A., & Martinez-Salas, E. (2010). Insights into the Biology of IRES Elements through Riboproteomic Approaches. Journal of Biomedicine and Biotechnology, 2010, 1-12. doi:10.1155/2010/458927Bernstein, J., Sella, O., Le, S.-Y., & Elroy-Stein, O. (1997). PDGF2/c-sismRNA Leader Contains a Differentiation-linked Internal Ribosomal Entry Site (D-IRES). Journal of Biological Chemistry, 272(14), 9356-9362. doi:10.1074/jbc.272.14.9356Scheper, G. C., Voorma, H. O., & Thomas, A. A. M. (1994). Basepairing with 18S ribosomal RNA in internal initiation of translation. FEBS Letters, 352(3), 271-275. doi:10.1016/0014-5793(94)00975-9Dresios, J., Chappell, S. A., Zhou, W., & Mauro, V. P. (2005). An mRNA-rRNA base-pairing mechanism for translation initiation in eukaryotes. Nature Structural & Molecular Biology, 13(1), 30-34. doi:10.1038/nsmb1031Reigadas, S., Pacheco, A., Ramajo, J., de Quinto, S. L., & Martinez-Salas, E. (2005). Specific interference between two unrelated internal ribosome entry site elements impairs translation efficiency. FEBS Letters, 579(30), 6803-6808. doi:10.1016/j.febslet.2005.11.015Ishitani, M., Xiong, L., Stevenson, B., & Zhu, J. K. (1997). Genetic analysis of osmotic and cold stress signal transduction in Arabidopsis: interactions and convergence of abscisic acid-dependent and abscisic acid-independent pathways. The Plant Cell, 9(11), 1935-1949. doi:10.1105/tpc.9.11.1935Knoester, M., van Loon, L. C., van den Heuvel, J., Hennig, J., Bol, J. F., & Linthorst, H. J. M. (1998). Ethylene-insensitive tobacco lacks nonhost resistance against soil-borne fungi. Proceedings of the National Academy of Sciences, 95(4), 1933-1937. doi:10.1073/pnas.95.4.1933Mathews, D. H., Sabina, J., Zuker, M., & Turner, D. H. (1999). Expanded sequence dependence of thermodynamic parameters improves prediction of RNA secondary structure. Journal of Molecular Biology, 288(5), 911-940. doi:10.1006/jmbi.1999.2700Zuker, M. (2003). Mfold web server for nucleic acid folding and hybridization prediction. Nucleic Acids Research, 31(13), 3406-3415. doi:10.1093/nar/gkg59
Rapid hormetic responses of photosystem ii photochemistry of clary sage to cadmium exposure
Five-day exposure of clary sage (Salvia sclarea L.) to 100 μM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca chan-nels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts de-creased. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the pho-toprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (ΦNO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (1O2) formation. A basal ROS level was detected in control plant leaves for optimal growth, while a low increased level of ROS under 5 days Cd exposure seemed to be beneficial for triggering defense responses, and a high level of ROS out of the boundaries (8 days Cd exposure), was harmful to plants. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered. However, exposure to a combination of Cd and high light or to Cd alone (8 days) resulted in an inhibition of PSII function-ality, indicating Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposure and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of “adaptive response” and “toxicity”, respectively. © 2020 by the authors. Licensee MDPI, Basel, Switzerland
Spatial heterogeneity of cadmium effects on salvia sclarea leaves revealed by chlorophyll fluorescence imaging analysis and laser ablation inductively coupled plasma mass spectrometry
In this study, for a first time (according to our knowledge), we couple the methodologies of chlorophyll fluorescence imaging analysis (CF-IA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), in order to investigate the effects of cadmium (Cd) accumulation on photosystem II (PSII) photochemistry. We used as plant material Salvia sclarea that grew hydroponically with or without (control) 100 μM Cd for five days. The spatial heterogeneity of a decreased effective quantum yield of electron transport (ΦPSII) that was observed after exposure to Cd was linked to the spatial pattern of high Cd accumulation. However, the high increase of non-photochemical quenching (NPQ), at the leaf part with the high Cd accumulation, resulted in the decrease of the quantum yield of non-regulated energy loss (ΦNO) even more than that of control leaves. Thus, S. sclarea leaves exposed to 100 μM Cd exhibited lower reactive oxygen species (ROS) production as singlet oxygen (1O2). In addition, the increased photoprotective heat dissipation (NPQ) in the whole leaf under Cd exposure was sufficient enough to retain the same fraction of open reaction centers (qp) with control leaves. Our results demonstrated that CF-IA and LA-ICP-MS could be successfully combined to monitor heavy metal effects and plant tolerance mechanisms. © 2019 by the authors
Excess Zinc Supply Reduces Cadmium Uptake and Mitigates Cadmium Toxicity Effects on Chloroplast Structure, Oxidative Stress, and Photosystem II Photochemical Efficiency in Salvia sclarea Plants
Salvia sclarea L. is a Cd2+ tolerant medicinal herb with antifungal and antimicrobial properties cultivated for its pharmacological properties. However, accumulation of high Cd2+ content in its tissues increases the adverse health effects of Cd2+ in humans. Therefore, there is a serious demand to lower human Cd2+ intake. The purpose of our study was to evaluate the mitigative role of excess Zn2+ supply to Cd2+ uptake/translocation and toxicity in clary sage. Salvia plants were treated with excess Cd2+ (100 µM CdSO4 ) alone, and in combination with Zn2+ (900 µM ZnSO4 ), in modified Hoagland nutrient solution. The results demonstrate that S. sclarea plants exposed to Cd2+ toxicity accumulated a significant amount of Cd2+ in their tissues, with higher concentrations in roots than in leaves. Cadmium exposure enhanced total Zn2+ uptake but also decreased its translocation to leaves. The accumulated Cd2+ led to a substantial decrease in photosystem II (PSII) photochemistry and disrupted the chloroplast ultrastructure, which coincided with an increased lipid peroxidation. Zinc application decreased Cd2+ uptake and translocation to leaves, while it mitigated oxidative stress, restoring chloroplast ultrastructure. Excess Zn2+ ameliorated the adverse effects of Cd2+ on PSII photochemistry, increasing the fraction of energy used for photochemistry (ΦPSII ) and restoring PSII redox state and maximum PSII efficiency (Fv/Fm), while decreasing excess excitation energy at PSII (EXC). We conclude that excess Zn2+ application eliminated the adverse effects of Cd2+ toxicity, reducing Cd2+ uptake and translocation and restoring chloroplast ultrastructure and PSII photochemical efficiency. Thus, excess Zn2+ application can be used as an important method for low Cd2+-accumulating crops, limiting Cd2+ entry into the food chain. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Tolerance mechanisms of the aromatic and medicinal plant salvia sclarea l. To excess zinc
In recent years, due to the development of industrial and agricultural production, heavy metal contamination has attracted increasing attention. Aromatic and medicinal plant Salvia sclarea L. (clary sage) is classified to zinc (Zn) accumulators and considered as a potential plant for the phytore-mediation of heavy metal polluted soils. In this study, an adaptation of clary sage to 900 µM (excess) Zn exposure for eight days in a hydroponic culture was investigated. The tolerance mechanisms under excess Zn exposure were assessed by evaluating changes in the nutrient uptake, leaf pigment and phenolic content, photosynthetic activity and leaf structural characteristics. The uptake and the distribution of Zn, as well as some essential elements such as: Ca, Mg, Fe, Mn and Cu, were examined by inductively coupled plasma mass spectrometry. The results revealed that Salvia sclarea is a Zn-accumulator plant that tolerates significantly high toxic levels of Zn in the leaves by increasing the leaf contents of Fe, Ca and Mn ions to protect the photosynthetic function and to stimulate the photosystem I (PSI) and photosystem II (PSII) activities. The exposure of clary sage to excess Zn significantly increased the synthesis of total phenolics and anthocyanins in the leaves; these play an important role in Zn detoxification and protection against oxidative stress. The lipid peroxidation and electrolyte leakage in leaves, used as clear indicators for heavy metal damage, were slightly increased. All these data highlight that Salvia sclarea is an economically interesting plant for the phytoextraction and/or phytostabilization of Zn-contaminated soils. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Cadmium toxicity in Salvia sclarea L.: An integrative response of element uptake, oxidative stress markers, leaf structure and photosynthesis
The herbal plant Salvia sclarea L. (clary sage) is classified to cadmium (Cd) accumulators and considered as a potential plant for phytoremediation of heavy metal polluted soil. However, the effect of Cd only treatment on the function of the photosynthetic apparatus of S. sclarea, as well as the mechanisms involved in Cd tolerance have not yet been studied in detail. This study was conducted to examine the integrative responses of S. sclarea plants exposed to a high Cd supply (100 µM) for 3 and 8 days by investigating element nutrient uptake, oxidative stress markers, pigment composition, photosynthetic performance and leaf structure. Measurements of the functional activities of photosystem I (PSI, by P700 photooxidation), photosystem II (PSII, by chlorophyll fluorescence parameters), the oxygen-evolving complex (oxygen evolution by Joliot- and Clark-type electrodes), as well as the leaf pigment and phenolic contents, were used to evaluate the protective mechanisms of the photosynthetic apparatus under Cd stress. Data suggested that the molecular mechanisms included in the photosynthetic tolerance to Cd toxicity involve strongly increased phenolic and anthocyanin contents, as well as an increased non-photochemical quenching and accelerated cyclic electron transport around PSI up to 61%, which protect the function of the photosynthetic apparatus under stress. Furthermore, the tolerance of S. sclarea to Cd stress is also associated with increased accumulation of Fe in leaves by 25%. All the above, clearly suggest that S. sclarea plants employ several different mechanisms to protect the function of the photosynthetic apparatus against Cd stress, which are discussed here. © 2021 The Author
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