title: Differential antioxidant responses to norflurazon-induced oxidative stress in maize.
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.
authors.affiliation: Department of Genetics, North Carolina State University, Raleigh 27695-7614, USA.
authors.forename: S
authors.initials: S
authors.lastname: Jung
authors.forename: S P
authors.initials: SP
authors.lastname: Kernodle
authors.forename: J G
authors.initials: JG
authors.lastname: Scandalios
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D018506:Gene Expression Regulation, Plant; D006540:Herbicides / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007527:Isoenzymes; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology; D030821:Plants, Genetically Modified; D011724:Pyridazines / Q000494:pharmacology*; D018749:RNA, Plant / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D003313:Zea mays / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D006540:Herbicides; D007527:Isoenzymes; D011724:Pyridazines; D018749:RNA, Plant; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; C008677:norflurazone