title: Differential response of antioxidative systems of maize (Zea mays L.) roots cell walls to osmotic and heavy metal stress.
abstract: An analysis of peroxidase and ascorbate oxidase activity, phenolic content and antioxidant capacity of isolated maize root cell walls was performed in controls and plants stressed with polyethylene glycol (PEG) or heavy metals, zinc or copper. Peroxidase activity (oxidative and peroxidative) was more pronounced in the ionic than in the covalent cell wall fraction. PEG induced an increase and Zn(2+) a decrease of both ionically bound peroxidase activities. In the covalent fraction, Cu(2+) decreased oxidative and increased peroxidative activity of peroxidase. Isoelectric focusing of ionically bound proteins and activity staining for peroxidase demonstrated increased intensities and appearance of new acidic isoforms, especially in Zn(2+) and PEG treatments. Most pronounced basic isoforms (pI ~ 7.5) in controls, decreased in intensity or completely disappeared in stressed plants. Ascorbate oxidase activity was significantly increased by PEG and decreased by Zn(2+) treatments, and highly correlated with peroxidase activity. Antioxidant capacity and total phenolics content increased in heavy metal-treated and decreased in PEG-treated plants. Analysis of individual phenolic components revealed p-coumaric and ferulic acids, as the most abundant, as well as ferulic acid dimers, trimers and tetramers in the cell walls; their quantity increased under stress conditions. Results presented demonstrate the existence of diverse mechanisms of plant response to different stresses.
authors.affiliation: Maize Research Institute, Zemun Polje, Belgrade, Serbia.
authors.forename: M
authors.initials: M
authors.lastname: Vuletić
authors.affiliation: Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia.
authors.forename: V
authors.initials: V
authors.lastname: Hadži-Tašković Šukalović
authors.affiliation: Maize Research Institute, Zemun Polje, Belgrade, Serbia.
authors.forename: K
authors.initials: K
authors.lastname: Marković
authors.affiliation: Maize Research Institute, Zemun Polje, Belgrade, Serbia.
authors.forename: N
authors.initials: N
authors.lastname: Kravić
authors.affiliation: Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia.
authors.forename: Ž
authors.initials: Ž
authors.lastname: Vučinić
authors.affiliation: Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia.
authors.forename: V
authors.initials: V
authors.lastname: Maksimović
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D019216:Metals, Heavy / Q000633:toxicity*; D009997:Osmotic Pressure; D018517:Plant Roots / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry; D003313:Zea mays / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D019216:Metals, Heavy; D011092:Polyethylene Glycols
keywords: Antioxidant; Zea mays; ascorbate oxidase; cell wall fractions; peroxidase; phenolics