@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{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{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{polidoros_mylona_scandalios_1998, title={Partial isolation and characterization of the maize alternative oxidase gene}, number={72}, journal={Maize Genetics Cooperation Newsletter}, author={Polidoros, A. N. and Mylona, P. V. and Scandalios, J. G.}, year={1998}, pages={68} }
 @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} }