@article{mylona_polidoros_scandalios_2007, title={Antioxidant gene responses to ROS-generating xenobiotics in developing and germinated scutella of maize}, volume={58}, ISSN={["1460-2431"]}, DOI={10.1093/jxb/erl292}, abstractNote={There is circumstantial evidence implicating reactive oxygen species (ROS) in the highly ordered temporal and spatial regulation of expression of the Cat and Sod antioxidant genes during seed development and germination in maize. In order to understand and provide experimental data for the regulatory role of ROS, the expression patterns of the Cat1, Cat2, Cat3, GstI, Sod3, Sod4, and Sod4A genes, as well as catalase (CAT) and superoxide dismutase (SOD) activity responses, were examined after treatments with ROS-generating xenobiotics in developing and germinated maize scutella. CAT and SOD activities increased at both stages in response to each xenobiotic examined in a dose-dependent and stage-specific manner. Individual Cat gene expression patterns were co-ordinated with isozyme patterns of enzymatic activity in scutella of developing seeds. This was not observed in germinated seeds where, although Cat1 expression was highly induced by ROS, there was not a similar increase of enzymatic CAT1 activity, suggesting the involvement of post-transcriptional regulation. Enhanced enzyme activities were synchronous with increases in steady-state transcript levels of specific Sod genes. The steady-state transcript level of GstI was elevated in all samples examined. Gene expression responses derived from this study along with similar results documented in previous reports were subjected to cluster analysis, revealing that ROS-generating compounds provoke similar effects in the expression patterns of the tested antioxidant genes. This could be attributable to common stress-related motifs present in the promoters of these genes.}, number={6}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Mylona, Photini V. and Polidoros, Alexios N. and Scandalios, John G.}, year={2007}, pages={1301–1312} }
 @misc{scandalios_2005, title={Oxidative stress: molecular perception and transduction of signals triggering antioxidant gene defenses}, volume={38}, ISSN={["1414-431X"]}, DOI={10.1590/S0100-879X2005000700003}, abstractNote={Molecular oxygen (O2) is the premier biological electron acceptor that serves vital roles in fundamental cellular functions. However, with the beneficial properties of O2 comes the inadvertent formation of reactive oxygen species (ROS) such as superoxide (O2*-), hydrogen peroxide, and hydroxyl radical (OH*). If unabated, ROS pose a serious threat to or cause the death of aerobic cells. To minimize the damaging effects of ROS, aerobic organisms evolved non-enzymatic and enzymatic antioxidant defenses. The latter include catalases, peroxidases, superoxide dismutases, and glutathione S-transferases (GST). Cellular ROS-sensing mechanisms are not well understood, but a number of transcription factors that regulate the expression of antioxidant genes are well characterized in prokaryotes and in yeast. In higher eukaryotes, oxidative stress responses are more complex and modulated by several regulators. In mammalian systems, two classes of transcription factors, nuclear factor kB and activator protein-1, are involved in the oxidative stress response. Antioxidant-specific gene induction, involved in xenobiotic metabolism, is mediated by the "antioxidant responsive element" (ARE) commonly found in the promoter region of such genes. ARE is present in mammalian GST, metallothioneine-I and MnSod genes, but has not been found in plant Gst genes. However, ARE is present in the promoter region of the three maize catalase (Cat) genes. In plants, ROS have been implicated in the damaging effects of various environmental stress conditions. Many plant defense genes are activated in response to these conditions, including the three maize Cat and some of the superoxide dismutase (Sod) genes.}, number={7}, journal={BRAZILIAN JOURNAL OF MEDICAL AND BIOLOGICAL RESEARCH}, author={Scandalios, JG}, year={2005}, month={Jul}, pages={995–1014} }
 @article{polidoros_mylona_pasentsis_scandalios_tsaftaris_2005, title={The maize alternative oxidase 1a (Aox1a) gene is regulated by signals related to oxidative stress}, volume={10}, ISSN={["1743-2928"]}, DOI={10.1179/135100005X21688}, abstractNote={Abstract We isolated and characterized the expression of Aox1a, a member of the maize alternative oxidase (Aox) small multigene family. Aox1a consists of four exons interrupted by three introns and its promoter harbors diverse stress-specific putative regulatory motifs pointing to complex regulation and response to multiple signals. Responses of Aox1a to such signals were examined and compared with those of maize glutathione S-transferase I (GstI), a typical oxidative stress inducible gene. Potassium cyanide (KCN) and hydrogen peroxide (H2O2) induced a rapid increase of the Aox1a and GstI transcripts, which was persisted in prolonged treatment at high H2O2 concentration only for Aox1a. High concentration of salicylic acid (SA) and salicyl hydroxamic acid (SHAM) induced Aox1a mRNA only after prolonged exposure, while GstI displayed an early strong induction, which declined thereafter. Nitric oxide (NO) induced a high increase of Aox1a after prolonged exposure at high concentration, while GstI displayed a weak response. Our results show that multiple signaling pathways, involved in stress responses, also participate and differentially regulate Aox1a and GstI in maize. A ROS-depended signaling event may be involved, suggesting an essential role of Aox1a under oxidative stress in maize.}, number={2}, journal={REDOX REPORT}, author={Polidoros, AN and Mylona, PV and Pasentsis, K and Scandalios, JG and Tsaftaris, AS}, year={2005}, month={Apr}, pages={71–78} }
 @article{menezes-benavente_kernodle_margis-pinheiro_scandalios_2004, title={Salt-induced antioxidant metabolism defenses in maize (Zea mays L.) seedlings}, volume={9}, ISSN={["1743-2928"]}, DOI={10.1179/135100004225003888}, abstractNote={Abstract Salinity alters general metabolic processes and enzymatic activities, causing increased production of reactive oxygen species (ROS). Expression of antioxidant defense genes would, in turn, be triggered to defend the cell against oxidative damage. We report that salt disturbed antioxidant metabolism in maize seedlings, causing detrimental effects on the growth and development of maize plantlets, increased hydrogen peroxide production and altered antioxidant activities and transcripts profiles. Excessive ROS levels were accompanied by increased catalase (CAT) activity in photosynthesizing shoots, along with induction of mRNA accumulation. Increased accumulation of superoxide dismutase (SOD) transcripts was also observed although no significant changes in total SOD enzymatic activity and isozyme profiles were detected. Higher salt concentrations (above 0.25 M NaCl) were highly detrimental to the plants, causing arrested growth and severe wilting, among other effects. Histochemical detection of H2O2 by 3,3-diaminobenzidine (DAB) staining indicated a collapse of the leaf veins, with hydrogen peroxide leaking to neighboring cells. In agreement to these observations, Sod1, Sod2, Sod4, Sod4A, as well as all Cat transcripts were severely inhibited in plants exposed to high salt concentrations.}, number={1}, journal={REDOX REPORT}, author={Menezes-Benavente, L and Kernodle, SP and Margis-Pinheiro, M and Scandalios, JG}, year={2004}, pages={29–36} }
 @article{ruzsa_scandalios_2003, title={Altered Cu metabolism and differential transcription of Cu/ZnSod genes in a Cu/ZnSOD-deficient mutant of maize: Evidence for a Cu-responsive transcription factor}, volume={42}, ISSN={["0006-2960"]}, DOI={10.1021/bi020551x}, abstractNote={Maize inbred line A351 exhibits extremely low levels of Cu/Zn superoxide dismutase (SOD) isozymes, three cytosolic and one chloroplastic, which are increased by supplying copper to near-toxic concentrations. Activities of the copper enzymes cytochrome c oxidase and ascorbate oxidase are also reduced. The level of expression of the maize copper chaperone for SOD is normal to elevated. The gene transcript encoding chloroplastic SOD-1 is present at normal levels, whereas RNA levels of the cytosolic SODs are low and increase with added copper, suggesting a promoter element and copper-dependent transcription factor common to the three genes. Although a reduced level of high-affinity copper transport in A351 cannot be ruled out, high transcript levels of a constitutively expressed metallothionein, suggesting increased copper chelation capacity and creating a general copper-deprivation effect, seem to be a likely cause of the reduced levels of copper enzyme activity and Cu/ZnSod gene transcripts. While exogenous copper does not affect the wild-type SOD activity or protein, it increases wild-type Cu/ZnSod transcript levels in a response similar to that of several yeast genes involved in copper sequestration and antioxidant defense. A sequence that is highly homologous to those of the copper-responsive transcription factors ACE1 (Saccharomyces cerevisiae) and AMT1 (Candida glabrata) is present in the promoters of three maize Cu/ZnSod genes.}, number={6}, journal={BIOCHEMISTRY}, author={Ruzsa, SM and Scandalios, JG}, year={2003}, month={Feb}, pages={1508–1516} }
 @article{guan_scandalios_2002, title={Catalase gene expression in response to auxin-mediated developmental signals}, volume={114}, ISSN={["1399-3054"]}, DOI={10.1034/j.1399-3054.2002.1140215.x}, abstractNote={The effect of auxin on maize catalase gene expression was examined at several different developmental stages during embryo and seedling development. All three catalase genes and their respective proteins were induced by both natural and synthetic auxin in immature embryos. Total catalase (CAT) activity increased dramatically in response to high concentrations of auxin, with CAT‐2, which is not normally expressed at this stage, being the isozyme most responsible for the increase. Cat1 transcript accumulated to high levels at 2–8 h after auxin treatment, while Cat2 and Cat3 transcripts increased dramatically, but only after 12 h. In CAT‐2 null mutant lines, the CAT‐1 isozyme compensated for the missing CAT‐2 activity and was the major isozyme responsible for the observed increase in total CAT activity. Auxin treatment mimics the germination process (i.e. induces germination) in immature embryos. Thus, the observed early induction of CAT‐1 and the later increase of CAT‐2 during the germination process may be due, in part, to changes in auxin content. In germinating embryos, auxin also induces total CAT activity and Cat transcript accumulation, although to a lesser extent. Auxin also induces Cat1 transcript accumulation in young leaves. The involvement of ROS in the auxin response is discussed.}, number={2}, journal={PHYSIOLOGIA PLANTARUM}, author={Guan, LQM and Scandalios, JG}, year={2002}, month={Feb}, pages={288–295} }
 @article{fink_scandalios_2002, title={Molecular evolution and structure-function relationships of the superoxide dismutase gene families in angiosperms and their relationship to other eukaryotic and prokaryotic superoxide dismutases}, volume={399}, ISSN={["1096-0384"]}, DOI={10.1006/abbi.2001.2739}, abstractNote={This study assesses whether the phylogenetic relationships between SODs from different organisms could assist in elucidating the functional relationships among these enzymes from evolutionarily distinct species. Phylogenetic trees and intron positions were compared to determine the relationships among these enzymes. Alignment of Cu/ZnSOD amino acid sequences indicates high homology among plant sequences, with some features that distinguish chloroplastic from cytosolic Cu/ZnSODs. Among eukaryotes, the plant SODs group together. Alignment of the Mn and FeSOD amino acid sequences indicates a higher degree of homology within the group of MnSODs (>70%) than within FeSODs (approximately 60%). Tree topologies are similar and reflect the taxonomic classification of the corresponding species. Intron number and position in the Cu/Zn Sod genes are highly conserved in plants. Genes encoding cytosolic SODs have seven introns and genes encoding chloroplastic SODs have eight introns, except the chloroplastic maize Sod1, which has seven. In Mn Sod genes the number and position of introns are highly conserved among plant species, but not among nonplant species. The link between the phylogenetic relationships and SOD functions remains unclear. Our findings suggest that the 5' region of these genes played a pivotal role in the evolution of function of these enzymes. Nevertheless, the system of SODs is highly structured and it is critical to understand the physiological differences between the SODs in response to different stresses in order to compare their functions and evolutionary history.}, number={1}, journal={ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS}, author={Fink, RC and Scandalios, JG}, year={2002}, month={Mar}, pages={19–36} }
 @article{jung_kernodle_scandalios_2001, title={Differential antioxidant responses to norflurazon-induced oxidative stress in maize}, volume={6}, ISSN={["1743-2928"]}, DOI={10.1179/135100001101536454}, abstractNote={Abstract This study examined the contribution of catalase (CAT) and superoxide dismutase (SOD) in the overall antioxidant response to norflurazon (NF)-induced oxidative stress in leaves, mesocotyls and scutella of maize (Zea mays). Maize catalase null mutants were used to provide insights into the role(s) of these isozymes. A substantial increase in Cat1 and Cat2 transcript levels occurred in NF-treated leaves in all maize lines examined. However, these two transcripts did not show a particular pattern of change in NF-treated scutella from 5-day postimbibition (dpi) and 18-day postpollination (dpp) maize. The NF-induced increase in Cat1 appeared to be dependent on excessive light energy caused by a lack of photoprotectant carotenoids, especially in leaves. In NF-treated leaves, the chloroplastic Cu/Zn-SOD-1 isozyme responded strongly compared to the cytosolic Cu/Zn-SOD and mitochondrial Mn-SOD-3 isozymes, suggesting the critical role of SOD-1 as a major component in chloroplastic antioxidant defenses. All SOD isozymes in the NF-treated scutella of various maize lines were consistent in their response to NF. The most significant increase was observed with Sod1 in NF-treated leaves; however, no significant Sod1 changes were observed in similarly treated scutella at 5 dpi and 18 dpp. These results suggest that the response of the Cat and Sod genes to NF is likely developmental and tissue-specific.}, number={5}, journal={REDOX REPORT}, author={Jung, S and Kernodle, SP and Scandalios, JG}, year={2001}, pages={311–317} }
 @article{kernodle_scandalios_2001, title={Structural organization, regulation, and expression of the chloroplastic superoxide dismutase Sod1 gene in maize}, volume={391}, ISSN={["1096-0384"]}, DOI={10.1006/abbi.2001.2397}, abstractNote={A cDNA and genomic clone encoding maize chloroplastic Cu/Zn superoxide dismutase Sod1 were isolated. Southern blot analysis indicated little homology between the chloroplastic (Sod1) and the cytosolic (Sod2, Sod4, Sod4A) cDNAs. Sequence analysis of the genomic clone revealed a promoter, transit peptide, and partial coding sequence. The promoter contained several response elements (e.g., for light, cold temperature, xenobiotics) that may be involved in the regulation of the Sod1 gene. Sod1 expression during development and in response to physiological and chemical stressors such as temperature, xenobiotics (paraquat), and light were examined.}, number={1}, journal={ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS}, author={Kernodle, SP and Scandalios, JG}, year={2001}, month={Jul}, pages={137–147} }
 @article{polidoros_mylona_scandalios_2001, title={Transgenic tobacco plants expressing the maize Cat2 gene have altered catalase levels that affect plant-pathogen interactions and resistance to oxidative stress}, volume={10}, ISSN={["0962-8819"]}, DOI={10.1023/A:1013027920444}, abstractNote={Transgenic tobacco genotypes expressing the maize Cat2 gene were developed with altered catalase (CAT) levels that resulted in a moderate increase of CAT activity in two transgenic lines. Bacterial infection, with a pathogen that does not share homology with the transgene, caused local and systemic down-regulation of the steady state mRNA levels of the 35S-driven transgene in a manner resembling post-transcriptional gene silencing (PTGS). Phenotypic symptoms of hypersensitive response (HR) and systemic acquired resistance (SAR) were similar in control SR1 and the transgenic genotypes. Induction of hin1, used as a molecular marker of plant responses to invading bacteria, displayed a similar pattern between control and transgenic lines, but some variation in the levels of expression was observed. The major difference was recorded in the ability of the plants to restrict bacterial growth during HR. All transgenic lines were more sensitive than control SR1, with two lines exhibiting a significantly reduced capacity to inhibit bacterial growth. This is consistent with the putative enhanced capacity of transgenic lines containing the maize Cat2 gene to more effectively remove H2O2, which may act as a direct antimicrobial agent. Steady state mRNA levels of PR-1 and PR-5 varied among the genotypes, possibly indicating differences in strength of the SAR signal. Transgenic line 2, which was the most sensitive during HR, was most effective in restricting bacterial growth during SAR. This indicates that a reverse correlation might exist between the severity of infection during HR and the ability to inhibit bacterial growth during SAR. Growth under high light conditions affected plant-pathogen interactions in control SR1, as well as in transgenic line 8. Early induction and higher expression of PR-1 and PR-5 was detected in both SR1 and line 8 in high light-grown plants as compared with their low light-grown counterparts. Our data indicate that growth under high light conditions can predispose plants to better resist pathogen attack, and may amplify local and systemic defense signals. Finally, one transgenic line, which exhibited 1.3-fold higher average CAT activity in comparison with the untransformed SR1 control, suffered significantly less methyl viologen (MV) damage than untransformed control plants at moderate and high MV concentrations.}, number={6}, journal={TRANSGENIC RESEARCH}, author={Polidoros, AN and Mylona, PV and Scandalios, JG}, year={2001}, month={Dec}, pages={555–569} }
 @article{scandalios_acevedo_ruzsa_2000, title={Catalase gene expression in response to chronic high temperature stress in maize}, volume={156}, ISSN={["0168-9452"]}, DOI={10.1016/S0168-9452(00)00235-1}, abstractNote={Catalase gene expression was characterized in the scutellum of maize seedlings grown at normal (25 degrees C) and elevated temperatures (35 and 40 degrees C). Chronic elevated temperatures reduce scutellar catalase activity most noticeably in the inbred lines W64A and R6-67, which express all three CAT isozymes (CAT-1, CAT-2, and CAT-3). The observed decline in catalase activity is primarily attributed to a decrease in the amount of CAT-2 isozyme, due to diminished levels of the Cat2 transcript. As CAT-2 activity levels are regulated by the trans-acting gene locus Car1, it is possible that the Car1 gene product is inhibited at the elevated temperatures. In maize lines null for CAT-2 or both CAT-2 and CAT-3, the relative levels of Cat1 transcript, although steady throughout the 10 days post-imbibition scutellar profile, are slightly higher with increasing temperatures. This might indicate that, in thermally stressed seedlings, the accumulation and/or stability of Cat1 mRNA might compensate for the lack of Cat2 transcript in a tissue where Cat2 mRNA normally accumulates during the developmental period examined. These observations, along with the drastic reduction in seed germination and seedling height at chronically elevated growth temperatures, suggest that developmental arrest, rather than oxidative stress, might be the cause for the observed results relative to Cat gene expression under such conditions.}, number={1}, journal={PLANT SCIENCE}, author={Scandalios, JG and Acevedo, A and Ruzsa, S}, year={2000}, month={Jul}, pages={103–110} }
 @article{guan_scandalios_2000, title={Catalase transcript accumulation in response to dehydration and osmotic stress in leaves of maize viviparous mutants}, volume={5}, ISSN={["1743-2928"]}, DOI={10.1179/135100000101535951}, abstractNote={Abstract The effect of osmotic stress and dehydration on maize catalase transcript accumulation was examined in leaves of abscisic acid (ABA)-deficient and ABA-insensitive mutants. We have found that the response of Cat1 to osmotic stress and dehydration is not via an ABA-mediated pathway in young leaves, suggesting that there are two different mechanisms by which Cat1 responds to osmotic stress in embryos and in leaves. The Cat2 transcript increased in response to osmotic stress, but was repressed by dehydration. On the other hand, the Cat3 transcript is up-regulated by dehydration and osmotic stress only in ABA-deficient mutant leaves, implying that ABA may act as a repressor for Cat3 expression in response to dehydration and high osmoticum. We also found that the VP1 trans-acting factor is not required for the induction of Cat1 by ABA in leaves, but may play a role in stabilizing the Cat1 transcript after an initial induction. The exact nature of the signals triggering Cat responses to osmotic stress and dehydration is not clear. We speculate that oxygen free radicals may play a role in this response. Osmotic stress and dehydration may indirectly induce production of oxygen free radicals in leaves, thus triggering the antioxidant response.}, number={6}, journal={REDOX REPORT}, author={Guan, LMQ and Scandalios, JG}, year={2000}, pages={377–383} }
 @article{guan_zhao_scandalios_2000, title={Cis-elements and trans-factors that regulate expression of the maize Cat1 antioxidant gene in response to ABA and osmotic stress: H2O2 is the likely intermediary signaling molecule for the response}, volume={22}, ISSN={["0960-7412"]}, DOI={10.1046/j.1365-313x.2000.00723.x}, abstractNote={Summary}, number={2}, journal={PLANT JOURNAL}, author={Guan, LQM and Zhao, J and Scandalios, JG}, year={2000}, month={Apr}, pages={87–95} }
 @article{guan_scandalios_2000, title={Hydrogen peroxide-mediated catalase gene expression in response to wounding}, volume={28}, ISSN={["1873-4596"]}, DOI={10.1016/S0891-5849(00)00212-4}, abstractNote={The effect of wounding on catalase expression was examined in embryos and leaves of maize. All three Cat genes are upregulated in response to wounding in immature embryos. Cat expression also increased in response to jasmonic acid (JA), raising the possibility that JA and wounding may share a common signal transduction pathway in upregulating Cat mRNA in immature embryos. In young leaves, only Cat1 and Cat3 transcripts increase in response to wounding, but JA does not play a role. Cat1 and Cat3 transcript accumulation also increases in response to wounding in both wild-type and mutant leaves deficient in abscisic acid (ABA), implying that Cat1 and Cat3 induction in response to wounding is not mediated by ABA in leaves. Transient assays using the Cat1 promoter fused with the reporter gene Gus, showed that the DNA sequence motif responsible for Cat1 upregulation by wounding overlaps with the ABA-responsive element (ABRE, G-box) in the Cat1 promoter. The exact nature of the signals triggering the Cat responses to wounding is not clear at this point, but some evidence indicates that reactive oxygen species (ROS) play a role in this response. In fact, we have found that endogenous H(2)O(2) levels increase in wounded leaves. Thus, wounding may indirectly induce the production of H(2)O(2) in leaves, triggering the antioxidant response.}, number={8}, journal={FREE RADICAL BIOLOGY AND MEDICINE}, author={Guan, LM and Scandalios, JG}, year={2000}, month={Apr}, pages={1182–1190} }
 @article{hite_auh_scandalios_1999, title={Catalase activity and hydrogen peroxide levels are inversely correlated in maize scutella during seed germination}, volume={4}, ISSN={["1743-2928"]}, DOI={10.1179/135100099101534710}, abstractNote={Temporal patterns of hydrogen peroxide (H2O2) levels and total catalase activity are presented for post-imbibition scutella from six maize inbred lines expressing variable catalase activity. In all lines examined, H2O2 levels were highest during the initial days post-imbibition (1-2 dpi) and decreased thereafter, while total catalase activity was lowest during early dpi (1-2 dpi) and reached maximal activity at 4-6 dpi. In three of the six lines tested, a simple inverse correlation between catalase activity and H2O2 level was significant by Spearman's rank (P < 0.01). In addition to the general decline in H2O2 level throughout the dpi period, a reproducible increase in H2O2 level was observed at 4-5 dpi in five of six lines examined. Mutant lines lacking CAT-3 activity demonstrated a temporal shift in the occurrence of this increase. The role of total catalase (and individual isozymes) in controlling H2O2 levels during germination and the role of H2O2 as a potential regulator of catalase expression during germination are discussed.}, number={1-2}, journal={REDOX REPORT}, author={Hite, DRC and Auh, C and Scandalios, JG}, year={1999}, pages={29–34} }
 @article{ruzsa_mylona_scandalios_1999, title={Differential response of antioxidant genes in maize leaves exposed to ozone}, volume={4}, ISSN={["1743-2928"]}, DOI={10.1179/135100099101534774}, abstractNote={Antioxidant enzymes function to eliminate reactive oxygen species (ROS) produced as a consequence of normal metabolic functions as well as environmental stress. In these studies, the responses of catalase (Cat), superoxide dismutase (Sod) and glutathione S-transferase (Gst), as well as D-ribulose-1,5-bisphosphate carboxylase/oxygenase (RbcS) genes were analyzed in 9- and 15-day postimbibition maize seedlings exposed to various ozone (O3) concentrations and time periods. After a single (acute) 6 h exposure, or 3, 6 and 10 consecutive days (chronic) exposure to O3, Cat1, Cat3, Gst1, Sod3, Sod4 and Sod4A transcript levels generally increased, while Cat2, RbcS and Sod1 levels decreased. Such changes in mRNA levels do not necessarily reflect parallel changes in the protein products of these genes. Changes in transcript levels seemed to be correlated with the spatial location of the isozymes encoded by the genes. The results are discussed with respect to gene regulation and expression, and the localization and function of these antioxidant enzymes during ozone-mediated oxidative stress.}, number={3}, journal={REDOX REPORT}, author={Ruzsa, SM and Mylona, P and Scandalios, JG}, year={1999}, pages={95–103} }
 @article{polidoros_scandalios_1999, title={Role of hydrogen peroxide and different classes of antioxidants in the regulation of catalase and glutathione S-transferase gene expression in maize (Zea mays L.)}, volume={106}, ISSN={["0031-9317"]}, DOI={10.1034/j.1399-3054.1999.106116.x}, abstractNote={The role of hydrogen peroxide (H2O2) and various antioxidants in the regulation of expression of the three Cat and Gst1 genes of maize (Zea mays L.) has been investigated. Low concentrations of H2O2 appeared to inhibit Cat1, Cat3, and Gst1 gene expression, while higher doses strongly induced these genes. Time course experiments indicated that high concentrations of H2O2 induced Cat1, Cat2, and Gst1 gene expression to higher levels, and in less time, than lower H2O2 concentrations. Induction of Cat3 was superimposed on the circadian regulation of the gene. These results demonstrate a direct signaling action of H2O2 in the regulation of antioxidant gene responses in maize.The effects of the antioxidant compounds N‐acetylcysteine, pyrrolidine dithiocarbamate, hydroquinone, and the electrophile antioxidant responsive element (ARE)‐inducer β‐naphthoflavone were quite different and specific for each gene/compound/concentration combination examined. The response of each gene to each antioxidant compound tested was unique, suggesting that the ability of these compounds to affect expression of the maize Cat and Gst1 genes may not be the result of a common (antioxidant) mode of action. A putative regulatory ARE motif involved in the regulation of antioxidant and oxidative stress gene responses in mammalian systems is present in the promoter of all three maize catalase genes and we tested its ability to interact with nuclear extracts prepared from 10 days post‐imbibition senescing scutella. Protein‐DNA interactions in the ARE motif and the U2 snRNA homologous regions of the Cat1 promoter were observed, suggesting that ARE may play a role in the high induction of Cat1 in a tissue which, due to senescence, is under oxidative stress.}, number={1}, journal={PHYSIOLOGIA PLANTARUM}, author={Polidoros, AN and Scandalios, JG}, year={1999}, month={May}, pages={112–120} }
 @article{polidoros_scandalios_1998, title={Circadian expression of the maize catalase Cat3 gene is highly conserved among diverse maize genotypes with structurally different promoters}, volume={149}, number={1}, journal={Genetics}, author={Polidoros, A. N. and Scandalios, J. G.}, year={1998}, pages={405–415} }
 @article{guan_scandalios_1998, title={Effects of the plant growth regulator abscisic acid and high osmoticum on the developmental expression of the maize catalase genes}, volume={104}, ISSN={["1399-3054"]}, DOI={10.1034/j.1399-3054.1998.1040317.x}, abstractNote={The effects of abscisic acid (ABA) and high osmoticum on catalase (Cat) gene expression in maize have been examined. Each Cat gene responds differently to ABA and osmotic stress at different developmental stages and in different tissues. Cat1 transcript accumulates to high levels in developing and germinating embryos, and in leaves. In embryos, Cat2 and Cat3 transcripts are up‐regulated only at very high ABA concentrations during late embryogenesis and in response to various concentrations of ABA in germinating embryos. Cat3 transcript is down‐regulated by ABA and osmotic stress in leaves. Accumulation of Cat1 transcript in response to osmotic stress is a consequence of increased endogenous ABA levels. Our data suggest that two separate pathways might be involved in the ABA‐mediated induction of Cat1. The Vp1 trans‐acting factor is required for maximum induction of Cat1 transcript in wild‐type (Vp1/—) and in W64A developing embryos; however, Vp1 is not required for inducing the Cat1 transcript in vp1 mutant developing embryos, nor in W64A germinating embryos or in leaves. Given the fact that the Cat genes have a known function, we hypothesize that the increase in Cat gene products in response to ABA is due, in part, to ABA‐mediated metabolic changes leading to changes in oxygen free radical levels, which in turn, lead to the induction of the antioxidant defense system.}, number={3}, journal={PHYSIOLOGIA PLANTARUM}, author={Guan, LQ and Scandalios, JG}, year={1998}, month={Nov}, pages={413–422} }
 @article{mylona_polidoros_scandalios_1998, title={Modulation of antioxidant responses by arsenic in maize}, volume={25}, ISSN={["0891-5849"]}, DOI={10.1016/S0891-5849(98)00090-2}, abstractNote={The effects of arsenic on the expression of the antioxidant genes encoding superoxide dismutase, catalase, and glutathione S-transferase, as well as the activity of SOD and CAT enzymes, were examined at different developmental stages and in different tissues. Both CAT and SOD activities increased in response to low concentrations (0.01-0.1 mM) of arsenic in developing maize embryos. In germinating embryos both CAT and SOD activities increased in response to a wide range of arsenic concentrations (0.01-10 mM). Cat1 transcript increased in response to arsenic in developing and germinating embryos and in young leaves. Conversely, Cat2 increased at low concentrations of arsenic only in germinating embryos. Cat3 transcript levels increased in response to low concentrations of arsenic only in developing embryos. Sod3 transcript increased at low concentrations of arsenic in developing, germinating embryos and in leaves. The cytosolic Sod4 and Sod4A increased in response to arsenic in germinating embryos, while only Sod4 transcript increased in response to arsenic in leaves. Expression of Gst1 was similar to that of Cat1 in all tissues examined. These results indicate that arsenic triggers tissue and developmental stage specific defense responses of antioxidant and detoxification related genes in maize.}, number={4-5}, journal={FREE RADICAL BIOLOGY AND MEDICINE}, author={Mylona, PV and Polidoros, AN and Scandalios, JG}, year={1998}, month={Sep}, pages={576–585} }
 @article{guan_scandalios_1998, title={Two structurally similar maize cytosolic superoxide dismutase genes, Sod4 and Sod4A, respond differentially to abscisic acid and high osmoticum}, volume={117}, ISSN={["1532-2548"]}, DOI={10.1104/pp.117.1.217}, abstractNote={Abstract}, number={1}, journal={PLANT PHYSIOLOGY}, author={Guan, LQ and Scandalios, JG}, year={1998}, month={May}, pages={217–224} }
 @article{boldt_scandalios_1997, title={Influence of UV-light on the expression of the Cat2 and Cat3 catalase genes in maize}, volume={23}, ISSN={["1873-4596"]}, DOI={10.1016/S0891-5849(97)00111-1}, abstractNote={The effects of UV (ultraviolet) -irradiation on the expression of the antioxidant genes Cat2 and Cat3, encoding the CAT-2 and CAT-3 catalases in maize were examined. Cat2 and Cat3 transcript accumulation was analyzed in leaves of maize seedlings grown under different light conditions, and subsequently exposed to UV-light. Under DD-(constant darkness) and LL- (continuous light) conditions, as well as under a 12h D/L- (dark/light) photoperiod, the Cat2 mRNA was expressed at low and constant levels. In contrast, Cat3 transcript accumulation was constant and about 10 times higher than that of Cat2 under DD or LL, while the expression of Cat3 exhibits a typical circadian rhythm under a 12h D/L photoperiod. UV- light pulses in the range of 290 to 400 nm strongly induce the expression of Cat2. Upon removing the UV-B portion (290-310 nm) of the UV-spectrum the maximal Cat2 transcript level was reduced by about 60%. On applying UV-light of the same quality in addition to visible light, the expression of Cat2 was induced. DNA damage caused by UV-light and induction mediated by a UV-light photosensory system are suggested. Further, it is suggested that the Cat3 circadian rhythm may be regulated by a blue light/UV-A and a UV-B photoreceptor. If DD and LL grown plants that exhibit no circadian oscillation, were exposed to constant UV-light in the range of 290 to 400 nm a circadian rhythm was induced; indicating that UV-light may function as an additional environmental cue to entrain the Cat3 circadian rhythm. Since, Cat2 and Cat3 showed distinct responses to UV light, it is suggested that both genes may act to scavenge reactive oxygen species (ROS) generated by UV-light to protect the plant from oxidative damage.}, number={3}, journal={FREE RADICAL BIOLOGY AND MEDICINE}, author={Boldt, R and Scandalios, JG}, year={1997}, pages={505–514} }
 @article{scandalios_1997, title={Introduction}, volume={23}, ISSN={["0891-5849"]}, DOI={10.1016/S0891-5849(97)00106-8}, abstractNote={Post-harvest applications of UV-C radiation have proven very efficient in reducing the development of post-harvest diseases in many species including lettuce (Lactuca sativa L.). Several studies suggest that UV-C radiation is effective not only because of its disinfecting effect but also because it may stimulate plant defenses. Pre-harvest treatment with UV-C radiation may thus offer an interesting potential for lettuce protection, provided that application doses are effective while excluding any harmful effects on the plants. Here we provide evidence that 0.85 kJ m−2 and 1.70 kJ m−2 represent doses of UV-C radiation that are not deleterious for lettuce plants. We used several criteria to evaluated the effect of UV-C radiation on the plant, including histological observations; the concentration of malondialdehyde, an indicator of membrane integrity, as well as parameters derived from measurements of chlorophyll fluorescence, such as maximal efficiency of photosystem II (Fv/Fm) and the Performance Index of Strasser. We observed that a single dose of 0.85 kJ m−2 slightly increased plant resistance to grey mould (Botrytis cinerea L.) while a single dose of 1.70 kJ m−2 had the opposite effect. When a 0.85 kJ m−2 dose was applied 4 times, at two-day intervals, there was an increase in the total phenol content of leaves, and in PAL, CAT, and MDAHR activities. Leaves inoculated 2 days after the latter UV-C treatment showed significantly decreased sensitivity (−30%) when compared to the control.}, number={3}, journal={FREE RADICAL BIOLOGY AND MEDICINE}, author={Scandalios, JG}, year={1997}, pages={471–472} }
 @article{badiani_paolacci_fusari_dovidio_scandalios_porceddu_sermanni_1997, title={Non-optimal growth temperatures and antioxidants in the leaves of Sorghum bicolor (L.) moench .2. Short-term acclimation}, volume={151}, ISSN={["0176-1617"]}, DOI={10.1016/S0176-1617(97)80005-3}, abstractNote={In pursuing previous studies on long-term acclimation to non-optimal, non-stressing growth temperatures (Badiani et al., 1993 b; Paolacci et al., 1997; Fusari et al., in press), the foliar antioxidant status and the photosynthetic capacity were evaluated in two sorghum [Sorghum bicolor (L.) Moench.] cultivars of different agroclimatic provenance, namely Aralba and ICSV 112, which were grown at the near-optimal temperature of 27 ± 0.3 °C and then gradually (1°Ch−1) and transiently (up to 120 h) exposed to suboptimal, 17 ± 0.4 °C, or supraoptimal, 37 ± 0.1 °C, temperatures, under moderate light intensity and ad libitum water and mineral nutrition. Comparative analysis of short-term and long-term responses to non-optimal growth temperatures suggested that: i) even realistic, i.e. limited and gradual, upward or downward shifts from the normative growth temperature, incapable of causing evident stress symptoms, might per se enhance the formation of reactive oxygen species whose effect, albeit not drastic, appear to be more noxious during the early stages of the exposure; ii) this disthermia-driven oxidative burst triggers almost immediate and extensive changes in all of the major antioxidant metabolites and scavenging enzymes. This could be aimed at preparing plant tissues in case moderate disthermia flows into authentic temperature stress; iii) certain short-term antioxidant changes persist beyond the relief of the disthermic regimes; and iv) however, in case the exposure to non-optimal growth temperatures becomes chronic, long-term adjustment processes take place, consisting of increases in protective pigments, ascorbic acid and glutathione, but without the involvement of antioxidant enzymes. Such a strategy might be aimed at keeping disthermia-dependent oxidative stress under control at the lowest possible price in terms of metabolic resources.}, number={4}, journal={JOURNAL OF PLANT PHYSIOLOGY}, author={Badiani, M and Paolacci, AR and Fusari, A and DOvidio, R and Scandalios, JG and Porceddu, E and Sermanni, GG}, year={1997}, month={Oct}, pages={409–421} }
 @article{polidoros_scandalios_1997, title={Response of the maize catalases to light}, volume={23}, ISSN={["1873-4596"]}, DOI={10.1016/S0891-5849(97)00110-X}, abstractNote={The three maize catalase genes respond differentially to light signals. Expression of Cat1 is light independent while expression of Cat2 and Cat3 is light responsive. Upon exposure to light there is rapid accumulation of CAT-2 protein in leaves, due to both increased transcript accumulation and increased translation of the Cat2 message. Short UV light pulses also cause a strong transient induction of Cat2 gene expression, while long term exposure to UV does not affect the rate of Cat2 transcription. The Cat3 gene of maize exhibits a transcriptionally regulated circadian rhythm. The induction of the Cat3 circadian expression in etiolated leaves is probably regulated by a very low fluence phytochrome response; the involvement of a blue light/UV-A and a UV-B photoreceptor is also possible. Regulatory elements located on the Cat3 promoter have recently been identified and their significance in the complex light response of the gene is being investigated. Possible physiological role(s) of the light responding maize catalases Cat2 and Cat3 are discussed.}, number={3}, journal={FREE RADICAL BIOLOGY AND MEDICINE}, author={Polidoros, AN and Scandalios, JG}, year={1997}, pages={497–504} }
 @article{auh_scandalios_1997, title={Spatial and temporal responses of the maize catalases to low temperature}, volume={101}, ISSN={["1399-3054"]}, DOI={10.1034/j.1399-3054.1997.1010120.x}, number={1}, journal={PHYSIOLOGIA PLANTARUM}, author={Auh, CK and Scandalios, JG}, year={1997}, month={Sep}, pages={149–156} }
 @article{williamson_scandalios_1994, title={THE MAIZE (ZEA-MAYS L) CAT1 CATALASE PROMOTER DISPLAYS DIFFERENTIAL BINDING OF NUCLEAR PROTEINS ISOLATED FROM GERMINATED AND DEVELOPING EMBRYOS AND FROM EMBRYOS GROWN IN THE PRESENCE AND ABSENCE OF ABSCISIC-ACID}, volume={106}, ISSN={["1532-2548"]}, DOI={10.1104/pp.106.4.1373}, abstractNote={We previously demonstrated that amounts of Cat1 RNA in developing immature maize (Zea mays L.) embryos change in parallel with endogenous abscisic acid (ABA) content. In excised immature embryos, addition of ABA leads to a large increase in Cat1 RNA accumulation. The Cat1 transcript, however, also accumulates to high amounts in scutella of germinating embryos, where ABA content is low and decreasing. Here we show that application of ABA to germinated embryos no longer results in the up-regulation of the Cat1 transcript accumulation that is seen during embryogenesis. This suggests that factors other than ABA control Cat1 expression at this developmental stage. Using band-shift and southwestern analyses, we show that the change in sensitivity to ABA is paralleled by changes in nuclear proteins binding to a 28-bp region of the Cat1 promoter in vitro. One protein (CAT1BP-20) shows increased accumulation in the absence of ABA, suggesting that a repressor-mediated mechanism accounts for at least a portion of the ABA regulation of Cat1.}, number={4}, journal={PLANT PHYSIOLOGY}, author={WILLIAMSON, JD and SCANDALIOS, JG}, year={1994}, month={Dec}, pages={1373–1380} }
 @article{scandalios_1993, title={OXYGEN STRESS AND SUPEROXIDE DISMUTASES}, volume={101}, ISSN={["1532-2548"]}, DOI={10.1104/pp.101.1.7}, abstractNote={The accumulation of dioxygen in Earth's atmosphere allowed for the evolution of aerobic organisms that use O2 as the terminal electron acceptor, thus providing a higher yield of energy compared with fermentation and anaerobic respiration. For example, in aerobic metabolism, the complete breakdown of one molecule of glucose yields a total of 38 molecules of ATP, whereas the anaerobic breakdown of this same glucose molecule to ethanol and CO, yields only 8 ATPs. In its ground state, molecular O2 (dioxygen) is relatively unreactive, yet it is capable of giving rise to lethal reactive ,excited states as free radicals and derivatives. Utilization of O2 proceeds most readily via a complete stepwise, fourelectron reduction to water during which partially reduced reactive intermediates are generated (Fig. 1). The reactive species of reduced dioxygen include the superoxide radical (. 02-), hydrogen peroxide (H202), and the hydroxyl radical (. OH). These and the physiologically energized form of dioxygen, singlet oxygen ('O2), are the biologically most important O2 species. An activation energy of approximately 22 kcal/mol is required to raise molecular O2 from its ground state to its first singlet state. In higher plants, this energy is readily obtained from light quanta via such transfer molecules as Chl (Foote, 1976). A11 of these activated oxygen species are extremely reactive and cytotoxic in a11 organisms. These highly reactive species can react with unsaturated fatty acids to cause peroxidation of essential membrane lipids in the plasmalemma or intracellular organelles. Peroxidation damage of the plasmalemma leads to leakage of cellular contents, rapid desiccation, and cell death. Intracellular membrane damage can affect respiratory activity in mitochondria, cause pigment breakdown, and cause loss of carbon-fixing ability in chloroplasts. Severa1 Calvin-cycle enzymes within chloroplasts are extremely sensitive to H202, and high levels of H202 (the product of superoxide dismutation) directly inhibit C02 fixation (Kaiser, 1979). H202 has also been shown to be active with mixed function oxidases in marking severa1 types of enzymes for proteolytic degradation (Fucci et al., 1983). Superoxide and H202 can react in a "Haber-Weiss" reaction to generate the hydroxyl radical ( + OH), which is the most potent oxidant known. The hydroxyl radical indiscriminately and rapidly attacks virtually a11 macromolecules, leading to seri-}, number={1}, journal={PLANT PHYSIOLOGY}, author={SCANDALIOS, JG}, year={1993}, month={Jan}, pages={7–12} }
 @article{williamson_scandalios_1993, title={Plant antioxidant gene response to fungal pathogens}, volume={1}, DOI={10.1016/0966-842x(93)90140-m}, abstractNote={Antioxidant defense systems are a prominent element in plant responses to environmental stress. Activated oxygen species have themselves been implicated as both a part of the plant's defense against pathogen attack as well as the phytotoxic component of photosensitizing fungal toxins. Molecular analyses are just beginning to define how plant oxidant and antioxidant genes might integrate with other defense responses to provide effective protection against pathogen attack.}, number={6}, journal={Soil Science and Plant Nutrition}, author={Williamson, J. D. and Scandalios, J. G.}, year={1993}, pages={239–245} }
 @article{williamson_scandalios_1993, title={Response of the maize catalases and superoxide dismutases to cercosporin-containing fungal extracts: the pattern of catalase response in scutella is stage specific}, volume={88}, DOI={10.1034/j.1399-3054.1993.880122.x}, number={1}, journal={Physiologia Plantarum}, author={Williamson, J. D. and Scandalios, J. G.}, year={1993}, pages={159–166} }
 @article{williamson_scandalios_1992, title={DIFFERENTIAL RESPONSE OF MAIZE CATALASES TO ABSCISIC-ACID - VP1 TRANSCRIPTIONAL ACTIVATOR IS NOT REQUIRED FOR ABSCISIC ACID-REGULATED CAT1 EXPRESSION}, volume={89}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.89.18.8842}, abstractNote={In this paper we describe the distinctive responses of the maize catalases to the plant growth regulator abscisic acid (ABA). We analyzed RNA and enzyme accumulation in excised maize embryos and found that each catalase responded differently to exogenously applied ABA. Levels of Cat1 transcript and enzyme activity rapidly increased. In contrast, levels of Cat2 transcript and protein decreased, while Cat3 transcript levels were not affected. In developing kernels of the ABA-deficient/biosynthetic viviparous mutant vp5, lower levels of Cat1 RNA correlated with lower endogenous ABA levels when compared to measured levels in comparably aged wild-type siblings from the same ear. The maize vp1 mutant line is morphologically insensitive to normal endogenous levels of ABA. Analysis of the response of Cat1 to exogenously applied ABA in mutant and wild-type vp1 sibling embryos suggests that, unlike other ABA-responsive genes analyzed to date, the Vp1 gene product is not essential for the ABA-mediated regulation of Cat1. The significance of these responses to ABA in defining the roles of the various CATs in maize is discussed.}, number={18}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={WILLIAMSON, JD and SCANDALIOS, JG}, year={1992}, month={Sep}, pages={8842–8846} }
 @article{williamson_scandalios_1992, title={Differential response of maize catalase and superoxide dismutase to the photoactivated fungal toxin cercosporin}, volume={2}, DOI={10.1046/j.1365-313x.1992.t01-33-00999.x}, abstractNote={Summary}, number={3}, journal={Plant Journal}, author={Williamson, J. D. and Scandalios, J. G.}, year={1992}, pages={351–358} }
 @article{acevedo_williamson_scandalios_1991, title={Photoregulation of the Cat2 and Cat3 catalase genes in pigmented and pigment-deficient maize - The circadian regulation of Cat3 is superimposed on its quasi-constitutive expression in maize leaves}, volume={127}, number={3}, journal={Genetics}, author={Acevedo, A. and Williamson, J. D. and Scandalios, J. G.}, year={1991}, pages={601–607} }
 @article{scandalios_1990, title={Response of plant antioxidant defense genes to environmental stress}, volume={28}, journal={Advances in Genetics}, author={Scandalios, J. G.}, year={1990}, pages={1} }
 @book{scandalios_1987, title={Molecular genetics of development}, ISBN={0120176246}, publisher={San Diego: Academic Press}, author={Scandalios, J. G.}, year={1987} }