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Histone acetylation is directly related to gene expression. In yeast, the acetyltransferase general control nonderepressible-5 (GCN5) targets histone H3 and associates with transcriptional co-activators alteration/deficiency in activation-2 (ADA2) and alteration/deficiency in activation-3 (ADA3) in complexes like SAGA. Arabidopsis thaliana has two genes encoding proteins, designated ADA3a and ADA3b, that correspond to yeast ADA3. We investigated the role of ADA3a and ADA3b in regulating gene expression during flowering time. Specifically, we found that knock out mutants ada3a-2 and the double mutant ada3a-2 ada3b-2 lead to early flowering compared to the wild type plants under long day (LD) conditions and after moving plants from short days to LD. Consistent with ADA3a being a repressor of floral initiation, FLOWERING LOCUS T (FT) expression was increased in ada3a mutants. In contrast, other genes involved in multiple pathways leading to floral transition, including FT repressors, players in GA signaling, and members of the SPL transcriptional factors, displayed reduced expression. Chromatin immunoprecipitation analysis revealed that ADA3a affects the histone H3K14 acetylation levels in SPL3, SPL5, RGA, GAI, and SMZ loci. In conclusion, ADA3a is involved in floral induction through a GCN5-containing complex that acetylates histone H3 in the chromatin of flowering related genes.
Stylianos Poulios; Despoina Dadarou; Maxim Gavriilidis; Niki Mougiou; Nestoras Kargios; Vasileia Maliori; Amy Hark; John Doonan; Konstantinos Vlachonasios. The Transcriptional Adaptor Protein ADA3a Modulates Flowering of Arabidopsis thaliana. Cells 2021, 10, 904 .
AMA StyleStylianos Poulios, Despoina Dadarou, Maxim Gavriilidis, Niki Mougiou, Nestoras Kargios, Vasileia Maliori, Amy Hark, John Doonan, Konstantinos Vlachonasios. The Transcriptional Adaptor Protein ADA3a Modulates Flowering of Arabidopsis thaliana. Cells. 2021; 10 (4):904.
Chicago/Turabian StyleStylianos Poulios; Despoina Dadarou; Maxim Gavriilidis; Niki Mougiou; Nestoras Kargios; Vasileia Maliori; Amy Hark; John Doonan; Konstantinos Vlachonasios. 2021. "The Transcriptional Adaptor Protein ADA3a Modulates Flowering of Arabidopsis thaliana." Cells 10, no. 4: 904.
Plants of the genus Hypericum, commonly known as “St. Johnʼs wort” (“spathohorto” or “valsamo” in Greek), have been used since antiquity for their therapeutic properties. Wild-harvested Hypericum plants are still popular today in herbal medicines, commercially exploited due to their bioactive compounds, hypericin and hyperforin, which have antidepressant, antimicrobial and antiviral activity. Species identification of commercial products is therefore important and DNA barcoding, a molecular method that uses small sequences of organismsʼ genome as barcodes, can be useful in this direction. In this study, we collected plants of the genus Hypericum that grow wild in North-Eastern Greece and explored the efficiency of matK, and trnH-psbA regions as DNA barcodes for their identification. We focused on 5 taxa, namely H. aucheri, H. montbretii, H. olympicum, H. perforatum subsp. perforatum, and H. thasium, the latter a rare Balkan endemic species collected for the first time from mainland Greece. matK (using the genus-specific primers designed herein), trnH-psbA, and their combination were effectively used for the identification of the 5 Hypericum taxa and the discrimination of different H. perforatum subsp. perforatum populations. These barcodes were also able to discriminate Greek populations of H. perforatum, H. aucheri, H. montbretii, and H. olympicum from populations of the same species growing in other countries.
Ioanna Pyrka; Anastasia Stefanaki; Konstantinos E. Vlachonasios. DNA Barcoding of St. Johnʼs wort (Hypericum spp.) Growing Wild in North-Eastern Greece. Planta Medica 2021, 87, 528 -537.
AMA StyleIoanna Pyrka, Anastasia Stefanaki, Konstantinos E. Vlachonasios. DNA Barcoding of St. Johnʼs wort (Hypericum spp.) Growing Wild in North-Eastern Greece. Planta Medica. 2021; 87 (07):528-537.
Chicago/Turabian StyleIoanna Pyrka; Anastasia Stefanaki; Konstantinos E. Vlachonasios. 2021. "DNA Barcoding of St. Johnʼs wort (Hypericum spp.) Growing Wild in North-Eastern Greece." Planta Medica 87, no. 07: 528-537.
Transcription of protein-encoding genes starts with forming a pre-initiation complex comprised of RNA polymerase II and several general transcription factors. To activate gene expression, transcription factors must overcome repressive chromatin structure, which is accomplished with multiprotein complexes. One such complex, SAGA, modifies the nucleosomal histones through acetylation and other histone modifications. A prototypical histone acetyltransferase (HAT) known as general control non-repressed protein 5 (GCN5), was defined biochemically as the first transcription-linked HAT with specificity for histone H3 lysine 14. In this review, we analyze the components of the putative plant SAGA complex during plant evolution, and current knowledge on the biological role of the key components of the HAT module, GCN5 and ADA2b in plants, will be summarized.
Konstantinos Vlachonasios; Stylianos Poulios; Niki Mougiou. The Histone Acetyltransferase GCN5 and the Associated Coactivators ADA2: From Evolution of the SAGA Complex to the Biological Roles in Plants. Plants 2021, 10, 308 .
AMA StyleKonstantinos Vlachonasios, Stylianos Poulios, Niki Mougiou. The Histone Acetyltransferase GCN5 and the Associated Coactivators ADA2: From Evolution of the SAGA Complex to the Biological Roles in Plants. Plants. 2021; 10 (2):308.
Chicago/Turabian StyleKonstantinos Vlachonasios; Stylianos Poulios; Niki Mougiou. 2021. "The Histone Acetyltransferase GCN5 and the Associated Coactivators ADA2: From Evolution of the SAGA Complex to the Biological Roles in Plants." Plants 10, no. 2: 308.
Olive tree growth and reproduction are severely affected by temperature extremes, compromising fruit yield. In that aspect, the olive varieties “Koroneiki” and “Mastoidis” were employed in a mild cold stress experiment, imitating night frost incidents to assess their biochemical, physiological and reproductive functions in relation to genotype. The physiological performance of the stressed plants was not significantly altered, suggesting that both cultivars were well adapted to mild cold night stress. The biochemical response of the plants, regarding antioxidant enzymes, H2O2 and TBARS accumulation, confirmed that both cultivars could cope with the stress applied. The mRNA levels of the PPO gene, which participates in hydroxytyrosol biosynthesis and plant defense, were elevated after 24-h stress at 0 °C, in both cultivars with “Mastoidis” plants exhibiting higher levels for a longer period. Three more genes involved in hydroxytyrosol biosynthesis upregulated their expression levels as a response to cold stress. The numerous plant phenology aspects measured reinforced the conclusion that both cultivars responded to the stress applied. The results of the present study may contribute to better understanding olive tree adaptive responses to low temperature events, an abiotic stress condition that is often present in an open plantation, thus assisting farmers on breeding and cultivar selection.
Niki Mougiou; Boushra Baalbaki; Georgios Doupis; Nektarios Kavroulakis; Stylianos Poulios; Konstantinos Vlachonasios; Georgios Koubouris. The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype. Sustainability 2020, 12, 10065 .
AMA StyleNiki Mougiou, Boushra Baalbaki, Georgios Doupis, Nektarios Kavroulakis, Stylianos Poulios, Konstantinos Vlachonasios, Georgios Koubouris. The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype. Sustainability. 2020; 12 (23):10065.
Chicago/Turabian StyleNiki Mougiou; Boushra Baalbaki; Georgios Doupis; Nektarios Kavroulakis; Stylianos Poulios; Konstantinos Vlachonasios; Georgios Koubouris. 2020. "The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype." Sustainability 12, no. 23: 10065.
Olive tree is one of the most valuable crops cultivated for its oil that is rich in antioxidants. The beneficial effects of oleuropein and hydroxytyrosol (HT), the most abundant and the most powerful antioxidant respectively, as well as tyrosol, HT's precursor molecule, are well studied however their biosynthetic pathways are not yet clarified. The transcriptome analysis of the young olive fruit, cultivar "Koroneiki", revealed transcripts of all the enzymes used to reconstitute the biosynthetic pathway of tyrosol and HT in other organisms. We also identified transcripts of the genes that encode for enzymes involved in the secologanin biosynthesis, oleuropein's precursor molecule. Following the transcriptome analysis, the relative expression of the transcripts was monitored during fruit development and compared to the concentration of the 3 metabolites they synthesize at the same developmental stages. The highest expression levels, accompanied by the maximum concentration of the three metabolites, was found in the young olive fruit. The correlation between the expression profile and the metabolites' concentration indicates that the transcripts were correctly identified and the synthesis of the compounds is regulated at a transcriptional level. Interestingly, HT showed a sudden increment in the final developmental stage of the black mature fruit that is attributed to oleuropein catabolism.
Niki Mougiou; Fotini Trikka; Emmanouil Trantas; Filippos Ververidis; Antonios Makris; Anagnostis Argiriou; Konstantinos E. Vlachonasios. Expression of hydroxytyrosol and oleuropein biosynthetic genes are correlated with metabolite accumulation during fruit development in olive, Olea europaea , cv. Koroneiki. Plant Physiology and Biochemistry 2018, 128, 41 -49.
AMA StyleNiki Mougiou, Fotini Trikka, Emmanouil Trantas, Filippos Ververidis, Antonios Makris, Anagnostis Argiriou, Konstantinos E. Vlachonasios. Expression of hydroxytyrosol and oleuropein biosynthetic genes are correlated with metabolite accumulation during fruit development in olive, Olea europaea , cv. Koroneiki. Plant Physiology and Biochemistry. 2018; 128 ():41-49.
Chicago/Turabian StyleNiki Mougiou; Fotini Trikka; Emmanouil Trantas; Filippos Ververidis; Antonios Makris; Anagnostis Argiriou; Konstantinos E. Vlachonasios. 2018. "Expression of hydroxytyrosol and oleuropein biosynthetic genes are correlated with metabolite accumulation during fruit development in olive, Olea europaea , cv. Koroneiki." Plant Physiology and Biochemistry 128, no. : 41-49.
The histone acetyltransferase GCN5 and associated transcriptional coactivator ADA2b are required to couple endoreduplication and trichome branching. Mutation of ADA2b also disrupts the relationship between ploidy and leaf cell size. Dynamic chromatin structure has been established as a general mechanism by which gene function is temporally and spatially regulated, but specific chromatin modifier function is less well understood. To address this question, we have investigated the role of the histone acetyltransferase GCN5 and the associated coactivator ADA2b in developmental events in Arabidopsis thaliana. Arabidopsis plants with T-DNA insertions in GCN5 (also known as HAG1) or ADA2b (also known as PROPORZ1) display pleiotropic phenotypes including dwarfism and floral defects affecting fertility. We undertook a detailed characterization of gcn5 and ada2b phenotypic effects in rosette leaves and trichomes to establish a role for epigenetic control in these developmental processes. ADA2b and GCN5 play specific roles in leaf tissue, affecting cell growth and division in rosette leaves often in complex and even opposite directions. Leaves of gcn5 plants display overall reduced ploidy levels, while ada2b-1 leaves show increased ploidy. Endoreduplication leading to increased ploidy is also known to contribute to normal trichome morphogenesis. We demonstrate that gcn5 and ada2b mutants display alterations in the number and patterning of trichome branches, with ada2b-1 and gcn5-1 trichomes being significantly less branched, while gcn5-6 trichomes show increased branching. Elongation of the trichome stalk and branches also vary in different mutant backgrounds, with stalk length having an inverse relationship with branch number. Taken together, our data indicate that, in Arabidopsis, leaves and trichomes ADA2b and GCN5 are required to couple nuclear content with cell growth and morphogenesis.
Jenna Kotak; Marina Saisana; Vasilis Gegas; Nikoletta Pechlivani; Athanasios Kaldis; Panagiotis Papoutsoglou; Athanasios Makris; Julia Burns; Ashley L. Kendig; Minnah Sheikh; Cyrus Kuschner; Gabrielle Whitney; Hanna Caiola; John Doonan; Konstantinos E. Vlachonasios; Elizabeth R. McCain; Amy T. Hark. The histone acetyltransferase GCN5 and the transcriptional coactivator ADA2b affect leaf development and trichome morphogenesis in Arabidopsis. Planta 2018, 248, 613 -628.
AMA StyleJenna Kotak, Marina Saisana, Vasilis Gegas, Nikoletta Pechlivani, Athanasios Kaldis, Panagiotis Papoutsoglou, Athanasios Makris, Julia Burns, Ashley L. Kendig, Minnah Sheikh, Cyrus Kuschner, Gabrielle Whitney, Hanna Caiola, John Doonan, Konstantinos E. Vlachonasios, Elizabeth R. McCain, Amy T. Hark. The histone acetyltransferase GCN5 and the transcriptional coactivator ADA2b affect leaf development and trichome morphogenesis in Arabidopsis. Planta. 2018; 248 (3):613-628.
Chicago/Turabian StyleJenna Kotak; Marina Saisana; Vasilis Gegas; Nikoletta Pechlivani; Athanasios Kaldis; Panagiotis Papoutsoglou; Athanasios Makris; Julia Burns; Ashley L. Kendig; Minnah Sheikh; Cyrus Kuschner; Gabrielle Whitney; Hanna Caiola; John Doonan; Konstantinos E. Vlachonasios; Elizabeth R. McCain; Amy T. Hark. 2018. "The histone acetyltransferase GCN5 and the transcriptional coactivator ADA2b affect leaf development and trichome morphogenesis in Arabidopsis." Planta 248, no. 3: 613-628.
Eukaryotic initiation factor 4A (eIF4A) is a highly conserved RNA-stimulated ATPase and helicase involved in the initiation of messenger RNA translation. Previously, we found that eIF4A interacts with cyclin-dependent kinase A (CDKA), the plant ortholog of mammalian CDK1. Here, we show that this interaction occurs only in proliferating cells where the two proteins coassociate with 5′-cap-binding protein complexes, eIF4F or the plant-specific eIFiso4F. CDKA phosphorylates eIF4A on a conserved threonine residue (threonine-164) within the RNA-binding motif 1b TPGR. In vivo, a phospho-null (APGR) variant of the Arabidopsis (Arabidopsis thaliana) eIF4A1 protein retains the ability to functionally complement a mutant (eif4a1) plant line lacking eIF4A1, whereas a phosphomimetic (EPGR) variant fails to complement. The phospho-null variant (APGR) rescues the slow growth rate of roots and rosettes, together with the ovule-abortion and late-flowering phenotypes. In vitro, wild-type recombinant eIF4A1 and its phospho-null variant both support translation in cell-free wheat germ extracts dependent upon eIF4A, but the phosphomimetic variant does not support translation and also was deficient in ATP hydrolysis and helicase activity. These observations suggest a mechanism whereby CDK phosphorylation has the potential to down-regulate eIF4A activity and thereby affect translation.
Maxwell S. Bush; Olivier Pierrat; Candida Nibau; Veronika Mikitova; Tao Zheng; Fiona Corke; Konstantinos Vlachonasios; Laura K. Mayberry; Karen S. Browning; John H. Doonan. eIF4A RNA Helicase Associates with Cyclin-Dependent Protein Kinase A in Proliferating Cells and Is Modulated by Phosphorylation. Plant Physiology 2016, 172, 128 -140.
AMA StyleMaxwell S. Bush, Olivier Pierrat, Candida Nibau, Veronika Mikitova, Tao Zheng, Fiona Corke, Konstantinos Vlachonasios, Laura K. Mayberry, Karen S. Browning, John H. Doonan. eIF4A RNA Helicase Associates with Cyclin-Dependent Protein Kinase A in Proliferating Cells and Is Modulated by Phosphorylation. Plant Physiology. 2016; 172 (1):128-140.
Chicago/Turabian StyleMaxwell S. Bush; Olivier Pierrat; Candida Nibau; Veronika Mikitova; Tao Zheng; Fiona Corke; Konstantinos Vlachonasios; Laura K. Mayberry; Karen S. Browning; John H. Doonan. 2016. "eIF4A RNA Helicase Associates with Cyclin-Dependent Protein Kinase A in Proliferating Cells and Is Modulated by Phosphorylation." Plant Physiology 172, no. 1: 128-140.
The world demand for lavender essential oil is still increasing. Despite of growing interest and the commercial importance of lavender oil it is not clear how environmental and developmental factors influence the optimum period of harvesting lavender flowers for essential oil production. In this report, it was evaluated how the quality and quantity of Lavandula angustifolia cv. Etherio essential oil (EO) is influenced during blooming by environmental factors. It was examined if lavender EO is correlated with gene expression during blooming, targeting to manage the optimum EO harvesting time. The EO content was positively regulated by temperature and flowering stage development while it was negatively affected by rainfall during flowering period. The quality of EO and specifically linalool content was influenced by temperature, flower development, LaLINS expression and rainfall. Although rainfalls remarkably decrease linalool production, the quality of lavender oil was recovered after ten days, suggesting that linalool biosynthesis is regulated during flowering period by both environmental and developmental cues. It is suggested, that the optimum harvesting period to obtain valuable lavender essential oil is when flowering reaches at 60%, ambient temperature is over 26 °C and no precipitations were occurred ten days before harvesting.
C.N. Hassiotis; F. Ntana; Diamanto Lazari; S. Poulios; K.E. Vlachonasios. Environmental and developmental factors affect essential oil production and quality of Lavandula angustifolia during flowering period. Industrial Crops and Products 2014, 62, 359 -366.
AMA StyleC.N. Hassiotis, F. Ntana, Diamanto Lazari, S. Poulios, K.E. Vlachonasios. Environmental and developmental factors affect essential oil production and quality of Lavandula angustifolia during flowering period. Industrial Crops and Products. 2014; 62 ():359-366.
Chicago/Turabian StyleC.N. Hassiotis; F. Ntana; Diamanto Lazari; S. Poulios; K.E. Vlachonasios. 2014. "Environmental and developmental factors affect essential oil production and quality of Lavandula angustifolia during flowering period." Industrial Crops and Products 62, no. : 359-366.
Histone acetylation and complexes associated with this process are directly involved in chromatin regulation and gene expression. Among these, NuA4 complex is directly involved in acetylation of histone H4, H2A and H2A.Z. In yeast, the NuA4 complex contains the catalytic subunit, the histone acetyltransferase ESA1, and several associated components including YAF9. In this report we explored the biological role of YAF9a in Arabidopsis thaliana. Homozygous yaf9a-1 and yaf9a-3 mutants show early flowering phenotypes. Moreover, yaf9a-1 mutants displayed reduced expression of the flowering repressor FLC, whereas the expression of the flowering activators FT and SOC1 was induced in comparison to wild-type plants. Using chromatin immunoprecipitation assays with H4 tetra-acetylated antibodies we observed a positive correlation with gene expression profile of FLC and FT in yaf9a-1 mutants under long days. We therefore conclude that YAF9a in Arabidopsis is a negative regulator of flowering by controlling the H4 acetylation levels in the FLC and FT chromatin.
Vasiliki Zacharaki; Moussa Benhamed; Stylianos Poulios; David Latrasse; Panagiotis Papoutsoglou; Marianne Delarue; Konstantinos E. Vlachonasios. The Arabidopsis ortholog of the YEATS domain containing protein YAF9a regulates flowering by controlling H4 acetylation levels at the FLC locus. Plant Science 2012, 196, 44 -52.
AMA StyleVasiliki Zacharaki, Moussa Benhamed, Stylianos Poulios, David Latrasse, Panagiotis Papoutsoglou, Marianne Delarue, Konstantinos E. Vlachonasios. The Arabidopsis ortholog of the YEATS domain containing protein YAF9a regulates flowering by controlling H4 acetylation levels at the FLC locus. Plant Science. 2012; 196 ():44-52.
Chicago/Turabian StyleVasiliki Zacharaki; Moussa Benhamed; Stylianos Poulios; David Latrasse; Panagiotis Papoutsoglou; Marianne Delarue; Konstantinos E. Vlachonasios. 2012. "The Arabidopsis ortholog of the YEATS domain containing protein YAF9a regulates flowering by controlling H4 acetylation levels at the FLC locus." Plant Science 196, no. : 44-52.
Plant growth and crop production can be greatly affected by common environmental stresses such as drought, high salinity and low temperatures. Gene expression is affected by several abiotic stresses. Stress-inducible genes are regulated by transcription factors and epigenetic mechanisms such as histone modifications. In this Mini-Review, we have explored the role of transcriptional adaptor ADA2b in Arabidopsis responses to abiotic stress. ADA2b is required for the expression of genes involved in abiotic stress either by controlling H3 and H4 acetylation in the case of salt stress or affecting nucleosome occupancy in low temperatures response.
Konstantinos E. Vlachonasios; Athanasios Kaldis; Adriana Nikoloudi; Despina Tsementzi. The role of transcriptional coactivator ADA2b in Arabidopsis abiotic stress responses. Plant Signaling & Behavior 2011, 6, 1475 -1478.
AMA StyleKonstantinos E. Vlachonasios, Athanasios Kaldis, Adriana Nikoloudi, Despina Tsementzi. The role of transcriptional coactivator ADA2b in Arabidopsis abiotic stress responses. Plant Signaling & Behavior. 2011; 6 (10):1475-1478.
Chicago/Turabian StyleKonstantinos E. Vlachonasios; Athanasios Kaldis; Adriana Nikoloudi; Despina Tsementzi. 2011. "The role of transcriptional coactivator ADA2b in Arabidopsis abiotic stress responses." Plant Signaling & Behavior 6, no. 10: 1475-1478.
The transcriptional co-activator ADA2b is a component of GCN5-containing complexes in eukaryotes. In Arabidopsis, ada2b mutants result in pleiotropic developmental defects and altered responses to low-temperature stress. SGF29 has recently been identified as another component of GCN5-containing complexes. In the Arabidopsis genome there are two orthologs of yeast SGF29, designated as SGF29a and SGF29b. We hypothesized that, in Arabidopsis, one or both SGF29 proteins may work in concert with ADA2b to regulate genes in response to abiotic stress, and we set out to explore the role of SGF29a and ADA2b in salt stress responses. In root growth and seed germination assays, sgf29a-1 mutants were more resistant to salt stress than their wild-type counterparts, whereas ada2b-1 mutant was hypersensitive. The sgf29a;ada2b double mutant displayed similar phenotypes to ada2b-1 mutant with reduced salt sensitivity. The expression of several abiotic stress-responsive genes was reduced in ada2b-1 mutants after 3 h of salt stress in comparison with sgf29a-1 and wild-type plants. In the sgf29a-1;ada2b-1 double mutant, the salt-induced gene expression was affected similarly to ada2b-1. These results suggest that under salt stress the function of SGF29a was masked by ADA2b and perhaps SGF29a could play an auxiliary role to ADA2b action. In chromatin immunoprecipitation assays, reduced levels of histone H3 and H4 acetylation in the promoter and coding region of COR6.6, RAB18, and RD29b genes were observed in ada2b-1 mutants relative to wild-type plants. In conclusion, ADA2b positively regulates salt-induced gene expression by maintaining the locus-specific acetylation of histones H4 and H3.
Athanasios Kaldis; Despina Tsementzi; Oznur Tanriverdi; Konstantinos E. Vlachonasios. Arabidopsis thaliana transcriptional co-activators ADA2b and SGF29a are implicated in salt stress responses. Planta 2010, 233, 749 -762.
AMA StyleAthanasios Kaldis, Despina Tsementzi, Oznur Tanriverdi, Konstantinos E. Vlachonasios. Arabidopsis thaliana transcriptional co-activators ADA2b and SGF29a are implicated in salt stress responses. Planta. 2010; 233 (4):749-762.
Chicago/Turabian StyleAthanasios Kaldis; Despina Tsementzi; Oznur Tanriverdi; Konstantinos E. Vlachonasios. 2010. "Arabidopsis thaliana transcriptional co-activators ADA2b and SGF29a are implicated in salt stress responses." Planta 233, no. 4: 749-762.