title: Heme-heme oxygenase 1 system is involved in ammonium tolerance by regulating antioxidant defence in Oryza sativa.
abstract: Despite substantial evidence showing the ammonium-altered redox homeostasis in plants, the involvement and molecular mechanism of heme-heme oxygenase 1 (heme-HO1), a novel antioxidant system, in the regulation of ammonium tolerance remain elusive. To fill in these gaps, the biological function of rice HO1 (OsSE5) was investigated. Results showed that NH4 Cl up-regulated rice OsSE5 expression. Oxidative stress and subsequent growth inhibition induced by excess NH4 Cl was partly mitigated by pretreatment with carbon monoxide (CO, a by-product of HO1 activity) or intensified by zinc protoporphyrin (ZnPP, a potent inhibitor of HO1 activity). Pretreatment with HO1 inducer hemin, not only up-regulated OsSE5 expression and HO activity, but also rescued the down-regulation of antioxidant transcripts, total and related isozymatic activities, thus significantly counteracting the excess NH4 Cl-triggered reactive oxygen species overproduction, lipid peroxidation and growth inhibition. OsSE5 RNAi transgenic rice plants revealed NH4 Cl-hypersensitive phenotype with impaired antioxidant defence, both of which could be rescued by CO but not hemin. Transgenic Arabidopsis plants over-expressing OsSE5 also exhibited enhanced tolerance to NH4 Cl, which might be attributed to the up-regulation of several antioxidant transcripts. Altogether, these results illustrated the involvement of heme-HO1 system in ammonium tolerance by enhancing antioxidant defence, which may improve plant tolerance to excess ammonium fertilizer.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing, 210095, China; Laboratory Center of Life Sciences, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Xie
authors.forename: Yu
authors.initials: Y
authors.lastname: Mao
authors.forename: Sheng
authors.initials: S
authors.lastname: Xu
authors.forename: Heng
authors.initials: H
authors.lastname: Zhou
authors.forename: Xingliang
authors.initials: X
authors.lastname: Duan
authors.forename: Weiti
authors.initials: W
authors.lastname: Cui
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Guohua
authors.initials: G
authors.lastname: Xu
mesh_terms: D064751:Ammonium Compounds / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D002248:Carbon Monoxide / Q000494:pharmacology*; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D006427:Hemin / Q000494:pharmacology; D015227:Lipid Peroxidation; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D018384:Oxidative Stress; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D015854:Up-Regulation
chemical_list: D064751:Ammonium Compounds; D000975:Antioxidants; D017382:Reactive Oxygen Species; D006427:Hemin; D002248:Carbon Monoxide; D051547:Heme Oxygenase-1
keywords: Arabidopsis; OsSE5; rice