title: Response of ascorbate peroxidase isoenzymes and ascorbate regeneration system to abiotic stresses in Cucumis sativus L.
abstract: Ascorbate peroxidase (APX) isoenzymes, distributing in at least four distinct cell compartments, the chloroplastic stroma (sAPX) and thylakoid membrane (tAPX), microbody (mAPX) and cytosol (cAPX), catalyze the reduction of H(2)O(2) to water by using ascorbic acid (AsA) as specific electron donor. In order to better clarify the response of APX isoenzymes and AsA regeneration enzymes to abiotic stresses, the activities of APX isoenzymes as well as monodehydroascorbate reductase (MDAR), glutathione reductase (GR) and dehydroascorbate reductase (DHAR) were investigated in cucumber plants after heat, methyl viologen (MV) and H(2)O(2) treatments. The activities of cAPX, sAPX, mAPX increased after a slight decline throughout the experiment. Consistent closely with sAPX activity, the expression of sAPX followed a similar change pattern, indicating that sAPX was regulated at the transcriptional level. In contrast, constitutive expression was observed in tAPX activity and no significant changes in tAPX activity were found throughout the experiment. The increases in MDAR and GR were accompanied with enhanced level of AsA/DHA, implying that the AsA regeneration system plays an essential role in compensating AsA degradation.
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou, China 310029.
authors.forename: Xing Shun
authors.initials: XS
authors.lastname: Song
authors.forename: Wen Hai
authors.initials: WH
authors.lastname: Hu
authors.forename: Wei Hua
authors.initials: WH
authors.lastname: Mao
authors.forename: Joshua Otieno
authors.initials: JO
authors.lastname: Ogweno
authors.forename: Yan Hong
authors.initials: YH
authors.lastname: Zhou
authors.forename: Jing Quan
authors.initials: JQ
authors.lastname: Yu
mesh_terms: D060387:Ascorbate Peroxidases; D001205:Ascorbic Acid / Q000378:metabolism*; D002736:Chloroplasts / Q000187:drug effects / Q000201:enzymology; D018553:Cucumis sativus / Q000201:enzymology / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D008830:Microbodies / Q000201:enzymology / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D010088:Oxidoreductases / Q000378:metabolism; D010269:Paraquat / Q000494:pharmacology; D010544:Peroxidases / Q000378:metabolism*; D020524:Thylakoids / Q000201:enzymology / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D016877:Oxidants; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D009247:NADH, NADPH Oxidoreductases; C023927:monodehydroascorbate reductase (NADH); D005980:Glutathione Reductase; C020666:glutathione dehydrogenase (ascorbate); D010269:Paraquat; D001205:Ascorbic Acid