17-JExpBot_ROS-xenobiotics - Journal of Experimental...

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Journal of Experimental Botany, Vol. 58, No. 6, pp. 1301–1312, 2007 doi:10.1093/jxb/erl292 Advance Access publication 20 February, 2007 RESEARCH PAPER Antioxidant gene responses to ROS-generating xenobiotics in developing and germinated scutella of maize Photini V. Mylona 1, *, Alexios N. Polidoros 2 and John G. Scandalios 3 1 Agricultural Recearch Center of Northern Greece, NAGREF, 570 01 Thermi, Greece 2 Institute of Agrobiotechnology, CERTH, 6th km. Charilaou-Thermis Rd, PO Box 361, 570 01 Thermi, Greece 3 Department of Genetics, North Carolina State University, Raleigh, NC 25606, USA Received 11 August 2006; Revised 27 November 2006; Accepted 30 November 2006 Abstract 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 ger- mination 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 xeno- biotics 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-speciFc manner. Individual Cat gene expression patterns were co-ordinated with iso- zyme patterns of enzymatic activity in scutella of de- veloping 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 speciFc Sod genes. The steady-state transcript level of GstI was elevated in all samples examined. Gene expression responses de- rived from this study along with similar results docu- mented 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 pro- moters of these genes. Key words: Antioxidants, benzyl viologen, catalase, glutathione S -transferase, juglone, methyl viologen, paraquat, reactive oxygen species, ROS, superoxide dismutase. Introduction Seed development, germination, and post-germination seedling growth are well-regulated processes that involve high metabolic activity and generation of reactive oxygen species (ROS) in the cell (Bailly, 2004). In the maturation of orthodox seeds such as maize, ROS have mostly been involved in the Fnal stage of seed desiccation in relation to the acquisition of desiccation tolerance, but are also related to high metabolic activity and mitochondrial respiration during embryo development. After germination of oil seeds, ROS production has been mainly associated with b
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This note was uploaded on 09/13/2010 for the course DGPB 024e taught by Professor Alexiospolidoros during the Spring '10 term at Aristotle University of Thessaloniki.

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17-JExpBot_ROS-xenobiotics - Journal of Experimental...

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