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Plant and Cell Physiology
Faltin, Z., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Holland, D., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Velcheva, M., Alberta Research Council, Hwy 16A and 75 Street, Vegreville, AB, T9C 1T4, Canada
Tsapovetsky, M., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Roeckel-Drevet, P., UMR INRA 547-PIAF, Universit Blaise Pascal, 63177 Aubire Cedex, France
Handa, A.K., Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN 47907-2010, United States
Abu-Abied, M., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Friedman-Einat, M., Institute of Animal Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Eshdat, Y., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland, Israel Ministry of Agriculture and Rural Development, PO Box 30, 50250 Bet-Dagan, Ireland
Perl, A., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is overexpressed in plants under abiotic and biotic stress conditions that mediate oxidative stress. To study its biological role and its ability to confer stress resistance in plants, we tried to obtain transgenic plants overexpressing citrus (Citrus sinensis) PHGPx (cit-PHGPx). All attempts to obtain regenerated plants expressing this enzyme constitutively failed. However, when the enzyme's catalytic activity was abolished by active site-directed mutagenesis, transgenic plants constitutively expressing inactive cit-PHGPx were successfully regenerated. Constitutive expression of enzymatically active cit-PHGPx could only be obtained when transformation was based on non-regenerative processes. These results indicate that overexpression of the antioxidant enzyme PHGPx interferes with shoot organogenesis and suggests the involvement of reactive oxygen species (ROS) in this process. Using transgenic tobacco (Nicotiana tabacum) leaves obtained from plants transformed with a β-estradiol- inducible promoter, time-dependent induction of cit-PHGPx expression was employed. A pronounced inhibitory effect of cit-PHGPx on shoot formation was found to be limited to the early stage of the regeneration process. Monitoring the ROS level during regeneration revealed that upon cit-PHGPx induction, the lowest level of ROS correlated with the maximal level of shoot inhibition. Our results clearly demonstrate the essential role of ROS in the early stages of in vitro shoot organogenesis and the possible involvement of PHGPx in maintaining ROS homeostasis at this point. © 2010 The Author.
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Glutathione peroxidase regulation of reactive oxygen species level is crucial for in vitro plant differentiation
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Faltin, Z., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Holland, D., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Velcheva, M., Alberta Research Council, Hwy 16A and 75 Street, Vegreville, AB, T9C 1T4, Canada
Tsapovetsky, M., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Roeckel-Drevet, P., UMR INRA 547-PIAF, Universit Blaise Pascal, 63177 Aubire Cedex, France
Handa, A.K., Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN 47907-2010, United States
Abu-Abied, M., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Friedman-Einat, M., Institute of Animal Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Eshdat, Y., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland, Israel Ministry of Agriculture and Rural Development, PO Box 30, 50250 Bet-Dagan, Ireland
Perl, A., Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Ireland
Glutathione peroxidase regulation of reactive oxygen species level is crucial for in vitro plant differentiation
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is overexpressed in plants under abiotic and biotic stress conditions that mediate oxidative stress. To study its biological role and its ability to confer stress resistance in plants, we tried to obtain transgenic plants overexpressing citrus (Citrus sinensis) PHGPx (cit-PHGPx). All attempts to obtain regenerated plants expressing this enzyme constitutively failed. However, when the enzyme's catalytic activity was abolished by active site-directed mutagenesis, transgenic plants constitutively expressing inactive cit-PHGPx were successfully regenerated. Constitutive expression of enzymatically active cit-PHGPx could only be obtained when transformation was based on non-regenerative processes. These results indicate that overexpression of the antioxidant enzyme PHGPx interferes with shoot organogenesis and suggests the involvement of reactive oxygen species (ROS) in this process. Using transgenic tobacco (Nicotiana tabacum) leaves obtained from plants transformed with a β-estradiol- inducible promoter, time-dependent induction of cit-PHGPx expression was employed. A pronounced inhibitory effect of cit-PHGPx on shoot formation was found to be limited to the early stage of the regeneration process. Monitoring the ROS level during regeneration revealed that upon cit-PHGPx induction, the lowest level of ROS correlated with the maximal level of shoot inhibition. Our results clearly demonstrate the essential role of ROS in the early stages of in vitro shoot organogenesis and the possible involvement of PHGPx in maintaining ROS homeostasis at this point. © 2010 The Author.
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