title: Differential Antioxidant Responses and Perturbed Porphyrin Biosynthesis after Exposure to Oxyfluorfen and Methyl Viologen in Oryza sativa.
abstract: We compared antioxidant responses and regulation of porphyrin metabolism in rice plants treated with oxyfluorfen (OF) or methyl viologen (MV). Plants treated with MV exhibited not only greater increases in conductivity and malondialdehyde but also a greater decline in Fv/Fm, compared to plants treated with OF. MV-treated plants had greater increases in activities of superoxide dismutase (SOD) and catalase (CAT) as well as transcript levels of SODA and CATA than OF-treated plants after 28 h of the treatments, whereas increases in ascorbate peroxidase (APX) activity and transcript levels of APXA and APXB were greater in OF-treated plants. Both OF- and MV-treated plants resulted in not only down-regulation of most genes involved in porphyrin biosynthesis but also disappearance of Mg-porphyrins during the late stage of photooxidative stress. By contrast, up-regulation of heme oxygenase 2 (HO2) is possibly part of an efficient antioxidant response to compensate photooxidative damage in both treatments. Our data show that down-regulated biosynthesis and degradation dynamics of porphyrin intermediates have important roles in photoprotection of plants from perturbed porphyrin biosynthesis and photosynthetic electron transport. This study suggests that porphyrin scavenging as well as strong antioxidative activities are required for mitigating reactive oxygen species (ROS) production under photooxidative stress caused by OF and MV.
authors.affiliation: School of Life Sciences and Biotechnology, BK21 Plus KNU Creative Bioresearch Group, Kyungpook National University, Daegu 702-701, Korea. nhipt.hus@gmail.com.
authors.forename: Nhi-Thi
authors.initials: NT
authors.lastname: Pham
authors.affiliation: School of Life Sciences and Biotechnology, BK21 Plus KNU Creative Bioresearch Group, Kyungpook National University, Daegu 702-701, Korea. truewaykor@naver.com.
authors.forename: Jin-Gil
authors.initials: JG
authors.lastname: Kim
authors.affiliation: School of Life Sciences and Biotechnology, BK21 Plus KNU Creative Bioresearch Group, Kyungpook National University, Daegu 702-701, Korea. sjung@knu.ac.kr.
authors.forename: Sunyo
authors.initials: S
authors.lastname: Jung
mesh_terms: D060387:Ascorbate Peroxidases / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D055768:Halogenated Diphenyl Ethers / Q000494:pharmacology*; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology*; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011166:Porphyrins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism
chemical_list: D055768:Halogenated Diphenyl Ethers; D006540:Herbicides; D010940:Plant Proteins; D011166:Porphyrins; D017382:Reactive Oxygen Species; C016027:oxyfluorofen; D060387:Ascorbate Peroxidases; D002374:Catalase; D006419:Heme Oxygenase (Decyclizing); D013482:Superoxide Dismutase; D010269:Paraquat
keywords: antioxidant; methyl viologen; oxyfluorfen; photooxidative stress; porphyrin