Journal Article

Glutathione Peroxidase Regulation of Reactive Oxygen Species Level is Crucial for In Vitro Plant Differentiation

Zehava Faltin, Doron Holland, Margarita Velcheva, Marina Tsapovetsky, Patricia Roeckel-Drevet, Avtar K. Handa, Mohamad Abu-Abied, Miriam Friedman-Einat, Yuval Eshdat and Avihai Perl

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 51, issue 7, pages 1151-1162
Published in print July 2010 | ISSN: 0032-0781
Published online June 2010 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcq082
Glutathione Peroxidase Regulation of Reactive Oxygen Species Level is Crucial for In Vitro Plant Differentiation

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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.

Keywords: Glutathione peroxidase; Nicotiana tabacum; Reactive oxygen species; Redox regulation; Shoot regeneration; Transgenic plants

Journal Article.  7308 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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