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We investigated the influence of Salvia fruticosa colonization by the arbuscular mycorrhizal fungi (AMF) Rhizophagus irregularis on photosynthetic function by using chlorophyll fluorescence imaging analysis to evaluate the light energy use in photosystem II (PSII) of inoculated and non-inoculated plants. We observed that inoculated plants used significantly higher absorbed energy in photochemistry (ΦPSII) than non-inoculated and exhibited significant lower excess excitation energy (EXC). However, the increased ΦPSII in inoculated plants did not result in a reduced non-regulated energy loss in PSII (ΦNO), suggesting the same singlet oxygen (1O2) formation between inoculated and non-inoculated plants. The increased ΦPSII in inoculated plants was due to an increased efficiency of open PSII centers to utilize the absorbed light (Fv’/Fm’) due to a decreased non-photochemical quenching (NPQ) since there was no difference in the fraction of open reaction centers (qp). The decreased NPQ in inoculated plants resulted in an increased electron-transport rate (ETR) compared to non-inoculated. Yet, inoculated plants exhibited a higher efficiency of the water-splitting complex on the donor side of PSII as revealed by the increased Fv/Fo ratio. A spatial heterogeneity between the leaf tip and the leaf base for the parameters ΦPSII and ΦNPQ was observed in both inoculated and non-inoculated plants, reflecting different developmental zones. Overall, our findings suggest that the increased ETR of inoculated S. fruticosa contributes to increased photosynthetic performance, providing growth advantages to inoculated plants by increasing their aboveground biomass, mainly by increasing leaf biomass.
Michael Moustakas; Gülriz Bayçu; Ilektra Sperdouli; Hilal Eroğlu; Eleftherios P. Eleftheriou. Arbuscular Mycorrhizal Symbiosis Enhances Photosynthesis in the Medicinal Herb Salvia fruticosa by Improving Photosystem II Photochemistry. Plants 2020, 9, 962 .
AMA StyleMichael Moustakas, Gülriz Bayçu, Ilektra Sperdouli, Hilal Eroğlu, Eleftherios P. Eleftheriou. Arbuscular Mycorrhizal Symbiosis Enhances Photosynthesis in the Medicinal Herb Salvia fruticosa by Improving Photosystem II Photochemistry. Plants. 2020; 9 (8):962.
Chicago/Turabian StyleMichael Moustakas; Gülriz Bayçu; Ilektra Sperdouli; Hilal Eroğlu; Eleftherios P. Eleftheriou. 2020. "Arbuscular Mycorrhizal Symbiosis Enhances Photosynthesis in the Medicinal Herb Salvia fruticosa by Improving Photosystem II Photochemistry." Plants 9, no. 8: 962.
The effects of bisphenol A (BPA), a prevalent endocrine disruptor, on both interphase and mitotic microtubule array organization was examined by immunofluorescence microscopy in meristematic root cells of Triticum turgidum (durum wheat) and Allium cepa (onion). In interphase cells of A. cepa, BPA treatment resulted in substitution of cortical microtubules by annular/spiral tubulin structures, while in T. turgidum BPA induced cortical microtubule fragmentation. Immunolocalization of acetylated α-tubulin revealed that cortical microtubules of T. turgidum were highly acetylated, unlike those of A. cepa. In addition, elevation of tubulin acetylation by trichostatin A in A. cepa resulted in microtubule disruption similar to that observed in T. turgidum. BPA also disrupted all mitotic microtubule arrays in both species. It is also worth noting that mitotic microtubule arrays were acetylated in both plants. As assessed by BPA removal, its effects are reversible. Furthermore, taxol-stabilized microtubules were resistant to BPA, while recovery from oryzalin treatment in BPA solution resulted in the formation of ring-like tubulin conformations. Overall, these findings indicate the following: (1) BPA affects plant mitosis/cytokinesis by disrupting microtubule organization. (2) Microtubule disassembly probably results from impairment of free tubulin subunit polymerization. (3) The differences in cortical microtubule responses to BPA among the species studied are correlated to the degree of tubulin acetylation.
Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Eleftherios P. Eleftheriou. Tubulin Acetylation Mediates Bisphenol A Effects on the Microtubule Arrays of Allium cepa and Triticum turgidum. Biomolecules 2019, 9, 185 .
AMA StyleIoannis-Dimosthenis S. Adamakis, Emmanuel Panteris, Eleftherios P. Eleftheriou. Tubulin Acetylation Mediates Bisphenol A Effects on the Microtubule Arrays of Allium cepa and Triticum turgidum. Biomolecules. 2019; 9 (5):185.
Chicago/Turabian StyleIoannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Eleftherios P. Eleftheriou. 2019. "Tubulin Acetylation Mediates Bisphenol A Effects on the Microtubule Arrays of Allium cepa and Triticum turgidum." Biomolecules 9, no. 5: 185.
Previous studies have shown that excess tungsten (W), a rare heavy metal, is toxic to plant cells and may induce a kind of programmed cell death (PCD). In the present study we used transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) to investigate the subcellular malformations caused by W, supplied as 200 mg/L sodium tungstate (Na2WO4) for 12 or 24 h, in root tip cells of Pisum sativum (pea), The objective was to provide additional evidence in support of the notion of PCD induction and the presumed involvement of reactive oxygen species (ROS). It is shown ultrastructurally that W inhibited seedling growth, deranged root tip morphology, induced the collapse and deformation of vacuoles, degraded Golgi bodies, increased the incidence of multivesicular and multilamellar bodies, and caused the detachment of the plasma membrane from the cell walls. Plastids and mitochondria were also affected. By TEM, the endoplasmic reticulum appeared in aggregations of straight, curved or concentric cisternae, frequently enclosing cytoplasmic organelles, while by CLSM it appeared in bright ring-like aggregations and was severely disrupted in mitotic cells. However, no evidence of ROS increase was obtained. Overall, these findings support the view of a W-induced vacuolar destructive PCD without ROS enhancement.
Ioannis-Dimosthenis S. Adamakis; Eleftherios P. Eleftheriou. Structural Evidence of Programmed Cell Death Induction by Tungsten in Root Tip Cells of Pisum sativum. Plants 2019, 8, 62 .
AMA StyleIoannis-Dimosthenis S. Adamakis, Eleftherios P. Eleftheriou. Structural Evidence of Programmed Cell Death Induction by Tungsten in Root Tip Cells of Pisum sativum. Plants. 2019; 8 (3):62.
Chicago/Turabian StyleIoannis-Dimosthenis S. Adamakis; Eleftherios P. Eleftheriou. 2019. "Structural Evidence of Programmed Cell Death Induction by Tungsten in Root Tip Cells of Pisum sativum." Plants 8, no. 3: 62.
Bisphenol A (BPA) is a widespread environmental pollutant, reportedly harmful to living organisms. In plant cells, BPA was shown to disrupt microtubule (MT) arrays and perturb mitosis, but its effects on filamentous actin (F-actin) have not been explored. Here we studied the effects of BPA on actin filaments (AFs) in meristematic root tip and leaf cells of Zea mays, by fluorescent labeling and confocal microscopy. Considering the typical dynamic interaction between MTs and AFs, the effects on these two essential components of the plant cytoskeleton were correlated. It was found that BPA disorganized rapidly AFs in a concentration- and time-dependent manner. The fine filaments were first to be affected, followed by the subcortical bundles, resulting in rod- and ring-like conformations. The observed differences in sensitivity between protodermal and cortex cells were attributed to the deeper location of the latter. Depolymerization or stabilization of MTs by relevant drugs (oryzalin, taxol) revealed that AF susceptibility to BPA depends on MT integrity. Developing leaves required harder and longer treatment to be affected by BPA. Ontogenesis of stomatal complexes was highly disturbed, arrangement of AFs and MT arrays was disordered and accuracy of cell division sequence was deranged or completely arrested. The effect of BPA confirmed that subsidiary cell mother cell polarization is not mediated by F-actin patch neither of preprophase band organization. On the overall, it is concluded that AFs in plant cells constitute a subcellular target of BPA and their disruption depends on their crosstalk with MTs.
Konstantina Stavropoulou; Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Ermioni-Makedonia Arseni; Eleftherios P. Eleftheriou. Disruption of actin filaments in Zea mays by bisphenol A depends on their crosstalk with microtubules. Chemosphere 2018, 195, 653 -665.
AMA StyleKonstantina Stavropoulou, Ioannis-Dimosthenis S. Adamakis, Emmanuel Panteris, Ermioni-Makedonia Arseni, Eleftherios P. Eleftheriou. Disruption of actin filaments in Zea mays by bisphenol A depends on their crosstalk with microtubules. Chemosphere. 2018; 195 ():653-665.
Chicago/Turabian StyleKonstantina Stavropoulou; Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Ermioni-Makedonia Arseni; Eleftherios P. Eleftheriou. 2018. "Disruption of actin filaments in Zea mays by bisphenol A depends on their crosstalk with microtubules." Chemosphere 195, no. : 653-665.
Chromium (Cr) is an abundant heavy metal in nature, toxic to living organisms. As it is widely used in industry and leather tanning, it may accumulate locally at high concentrations, raising concerns for human health hazards. Though Cr effects have extensively been investigated in animals and mammals, in plants they are poorly understood. The present study was then undertaken to determine the ultrastructural malformations induced by hexavalent chromium [Cr(VI)], the most toxic form provided as 100 μM potassium dichromate (K2Cr2O7), in the root tip cells of the model plant Arabidopsis thaliana. A concentration-dependent decrease of root growth and a time-dependent increase of dead cells, callose deposition, hydrogen peroxide (H2O2) production and peroxidase activity were found in Cr(VI)-treated seedlings, mostly at the transition root zone. In the same zone, nuclei remained ultrastructurally unaffected, but in the meristematic zone some nuclei displayed bulbous outgrowths or contained tubular structures. Endoplasmic reticulum (ER) was less affected under Cr(VI) stress, but Golgi bodies appeared severely disintegrated. Moreover, mitochondria and plastids became spherical and displayed translucent stroma with diminished internal membranes, but noteworthy is that their double-membrane envelopes remained structurally intact. Starch grains and electron dense deposits occurred in the plastids. Amorphous material was also deposited in the cell walls, the middle lamella and the vacuoles. Some vacuoles were collapsed, but the tonoplast appeared integral. The plasma membrane was structurally unaffected and the cytoplasm contained opaque lipid droplets and dense electron deposits. All electron dense deposits presumably consisted of Cr that is sequestered from sensitive sites, thus contributing to metal tolerance. It is concluded that the ultrastructural changes are reactive oxygen species (ROS)-correlated and the malformations observed are organelle specific.
Eleftherios P. Eleftheriou; Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Maria Fatsiou. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana. International Journal of Molecular Sciences 2015, 16, 15852 -15871.
AMA StyleEleftherios P. Eleftheriou, Ioannis-Dimosthenis S. Adamakis, Emmanuel Panteris, Maria Fatsiou. Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana. International Journal of Molecular Sciences. 2015; 16 (7):15852-15871.
Chicago/Turabian StyleEleftherios P. Eleftheriou; Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Maria Fatsiou. 2015. "Chromium-Induced Ultrastructural Changes and Oxidative Stress in Roots of Arabidopsis thaliana." International Journal of Molecular Sciences 16, no. 7: 15852-15871.
Exposure of Arabidopsis thaliana young and mature leaves to the herbicide paraquat (Pq) resulted in a localized increase of hydrogen peroxide (H2O2) in the leaf veins and the neighboring mesophyll cells, but this increase was not similar in the two leaf types. Increased H2O2 production was concomitant with closed reaction centers (qP). Thirty min after Pq exposure despite the induction of the photoprotective mechanism of non-photochemical quenching (NPQ) in mature leaves, H2O2 production was lower in young leaves mainly due to the higher increase activity of ascorbate peroxidase (APX). Later, 60 min after Pq exposure, the total antioxidant capacity of young leaves was not sufficient to scavenge the excess reactive oxygen species (ROS) that were formed, and thus, a higher H2O2 accumulation in young leaves occurred. The energy allocation of absorbed light in photosystem II (PSII) suggests the existence of a differential photoprotective regulatory mechanism in the two leaf types to the time-course Pq exposure accompanied by differential antioxidant protection mechanisms. It is concluded that tolerance to Pq-induced oxidative stress is related to the redox state of quinone A (QA).
Julietta Moustaka; Georgia Tanou; Ioannis-Dimosthenis Adamakis; Eleftherios P. Eleftheriou; Michael Moustakas. Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana. International Journal of Molecular Sciences 2015, 16, 13989 -14006.
AMA StyleJulietta Moustaka, Georgia Tanou, Ioannis-Dimosthenis Adamakis, Eleftherios P. Eleftheriou, Michael Moustakas. Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana. International Journal of Molecular Sciences. 2015; 16 (12):13989-14006.
Chicago/Turabian StyleJulietta Moustaka; Georgia Tanou; Ioannis-Dimosthenis Adamakis; Eleftherios P. Eleftheriou; Michael Moustakas. 2015. "Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana." International Journal of Molecular Sciences 16, no. 12: 13989-14006.
Because the detrimental effects of chromium (Cr) to higher plants have been poorly investigated, the present study was undertaken to verify the toxic attributes of hexavalent chromium [Cr(VI)] to plant mitotic microtubules (MTs), to determine any differential disruption of MTs during mitosis of taxonomically related species and to clarify the relationship between the visualized chromosomal aberrations and the Cr(VI)-induced MT disturbance. For this purpose, 5-day-old uniform seedlings of Vicia faba, Pisum sativum, Vigna sinensis and Vigna angularis, all belonging to the Fabaceae family, were exposed to 250 μM Cr(VI) supplied as potassium dichromate (K2Cr2O7) for 24, 72 and 120 h and others in distilled water serving as controls. Root tip samples were processed for tubulin immunolabelling (for MT visualization) and DNA fluorescent staining (for chromosomal visualization). Microscopic preparations of cell squashes were then examined and photographed by confocal laser scanning microscopy (CLSM). Cr(VI) halted seedling growth turning roots brown and necrotic. Severe chromosomal abnormalities and differential disturbance of the corresponding MT arrays were found in all mitotic phases. In particular, in V. faba MTs were primarily depolymerized and replaced by atypical tubulin conformations, whereas in P. sativum, V. sinensis and V. angularis they became bundled in a time-dependent manner. In P. sativum, the effects were milder compared to those of the other species, but in all cases MT disturbance adversely affected the proper aggregation of chromosomes on the metaphase plate, their segregation at anaphase and organization of the new nuclei at telophase. Cr(VI) is very toxic to seedling growth. The particular effect depends on the exact stage the cell is found at the time of Cr(VI) entrance and is species-specific. Mitotic MT arrays are differentially deranged by Cr(VI) in the different species examined, even if they are taxonomically related, while their disturbance underlies chromosomal abnormalities. Results furthermore support the view that MTs may constitute a reliable, sensitive and universal subcellular marker for monitoring heavy metal toxicity.
Eleftherios P. Eleftheriou; Vasiliki A. Michalopoulou; Ioannis-Dimosthenis S. Adamakis. Aberration of mitosis by hexavalent chromium in some Fabaceae members is mediated by species-specific microtubule disruption. Environmental Science and Pollution Research 2015, 22, 7590 -7599.
AMA StyleEleftherios P. Eleftheriou, Vasiliki A. Michalopoulou, Ioannis-Dimosthenis S. Adamakis. Aberration of mitosis by hexavalent chromium in some Fabaceae members is mediated by species-specific microtubule disruption. Environmental Science and Pollution Research. 2015; 22 (10):7590-7599.
Chicago/Turabian StyleEleftherios P. Eleftheriou; Vasiliki A. Michalopoulou; Ioannis-Dimosthenis S. Adamakis. 2015. "Aberration of mitosis by hexavalent chromium in some Fabaceae members is mediated by species-specific microtubule disruption." Environmental Science and Pollution Research 22, no. 10: 7590-7599.
Bisphenol A (BPA), a widely used chemical in the plastics industry that displays weak oestrogenic properties, is an emerging environmental pollutant, potentially harmful to living organisms. The presumed cytotoxicity of BPA to plant cells has been poorly studied. To understand how BPA might influence plant cell division and affect the underlying cytoskeleton, the effects of BPA on the microtubule (MT) arrays of meristematic root-tip cells of Pisum sativum L. were investigated. Root tips of young seedlings were exposed to 20, 50 and 100 mg/L BPA for 1, 3, 6, 12 and 24 h. The effects of each treatment were determined by means of confocal laser scanning microscopy after immunolabelling of tubulin and counterstaining of DNA, and by use of light and transmission electron microscopy. It was found that BPA affected normal chromosome segregation, hampered the completion of cytokinesis and deranged interphase and mitotic MT arrays. BPA effects were dependent on the stage of each cell at the time of BPA entrance. Moreover, BPA induced the formation of macrotubules with a mean diameter of 32 ± 0.14 nm, compared with 23 ± 0.70 nm for the MT arrays in untreated cells. Finally, all MT arrays and macrotubules were depolymerised upon longer treatment. Taken together, the data suggest that BPA exerts acute anti-mitotic effects on meristematic root-tip cells of P. sativum, MT arrays constitute a primary sub-cellular target of BPA toxicity, and the manifested chromosomal abnormalities could be attributed to the disruption of the MT cytoskeleton.
Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Anna Cherianidou; Eleftherios P. Eleftheriou. Effects of bisphenol A on the microtubule arrays in root meristematic cells of Pisum sativum L. Mutation Research/Genetic Toxicology and Environmental Mutagenesis 2012, 750, 111 -120.
AMA StyleIoannis-Dimosthenis S. Adamakis, Emmanuel Panteris, Anna Cherianidou, Eleftherios P. Eleftheriou. Effects of bisphenol A on the microtubule arrays in root meristematic cells of Pisum sativum L. Mutation Research/Genetic Toxicology and Environmental Mutagenesis. 2012; 750 (1-2):111-120.
Chicago/Turabian StyleIoannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Anna Cherianidou; Eleftherios P. Eleftheriou. 2012. "Effects of bisphenol A on the microtubule arrays in root meristematic cells of Pisum sativum L." Mutation Research/Genetic Toxicology and Environmental Mutagenesis 750, no. 1-2: 111-120.
Tungsten (W) is a rare heavy metal, widely used in a range of industrial, military and household applications due to its unique physical properties. These activities inevitably have accounted for local W accumulation at high concentrations, raising concerns about its effects for living organisms. In plants, W has primarily been used as an inhibitor of the molybdoenzymes, since it antagonizes molybdenum (Mo) for the Mo-cofactor (MoCo) of these enzymes. However, recent advances indicate that, beyond Mo-enzyme inhibition, W has toxic attributes similar with those of other heavy metals. These include hindering of seedling growth, reduction of root and shoot biomass, ultrastructural malformations of cell components, aberration of cell cycle, disruption of the cytoskeleton and deregulation of gene expression related with programmed cell death (PCD). In this article, the recent available information on W toxicity in plants and plant cells is reviewed, and the knowledge gaps and the most pertinent research directions are outlined.
Ioannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Eleftherios P. Eleftheriou. Tungsten Toxicity in Plants. Plants 2012, 1, 82 -99.
AMA StyleIoannis-Dimosthenis S. Adamakis, Emmanuel Panteris, Eleftherios P. Eleftheriou. Tungsten Toxicity in Plants. Plants. 2012; 1 (2):82-99.
Chicago/Turabian StyleIoannis-Dimosthenis S. Adamakis; Emmanuel Panteris; Eleftherios P. Eleftheriou. 2012. "Tungsten Toxicity in Plants." Plants 1, no. 2: 82-99.
The grapevine (Vitis vinifera L.) cultivars ‘Agiorgitiko’ and ‘Malagouzia’, naturally infected with Grapevine rupestris stem pitting-associated virus (GRSPaV), were subjected to in vitro chemotherapy using the antiviral inosine 5′-monophosphate dehydrogenase inhibitors tiazofurin (TR), ribavirin (RBV) and mycophenolic acid (MPA). The chemotherapy lasted 80 days and was carried out as two consecutive treatments. Severe phytotoxicity, estimated after 40 days of culture, was observed in drug-treated explants, especially when high doses of TR were used. Phytotoxicity exhibited a cultivar- and chemical compound-dependent profile. The virus eradication status of the survived plantlets was determined by nested RT-PCR using total RNA templates, after 80 days of drug treatment and one year later, after the passage of one dormancy period, in potted plants grown in a greenhouse. Data indicated that the highest GRSPaV elimination in ‘Agiorgitiko’ was obtained with 10 μg ml−1 TR, 30 μg ml−1 RBV and 20 μg ml−1 MPA. The eradication rates were lower in the case of ‘Malagouzia’, where the highest ones were achieved after treatments with 15 μg ml−1 TR and 80 μg ml−1 MPA. This is the first report on GRSPaV elimination in grapevine following treatment with antiviral compounds, which could provide an alternative to the traditional methods of virus eradication through meristem culture and thermotherapy.
F. G. Skiada; V. I. Maliogka; N. I. Katis; E. P. Eleftheriou. Elimination of Grapevine rupestris stem pitting-associated virus (GRSPaV) from two Vitis vinifera cultivars by in vitro chemotherapy. European Journal of Plant Pathology 2012, 135, 407 -414.
AMA StyleF. G. Skiada, V. I. Maliogka, N. I. Katis, E. P. Eleftheriou. Elimination of Grapevine rupestris stem pitting-associated virus (GRSPaV) from two Vitis vinifera cultivars by in vitro chemotherapy. European Journal of Plant Pathology. 2012; 135 (2):407-414.
Chicago/Turabian StyleF. G. Skiada; V. I. Maliogka; N. I. Katis; E. P. Eleftheriou. 2012. "Elimination of Grapevine rupestris stem pitting-associated virus (GRSPaV) from two Vitis vinifera cultivars by in vitro chemotherapy." European Journal of Plant Pathology 135, no. 2: 407-414.