Antioxidative response in variegated Pelargonium zonale leaves and generation of extracellular H2O2in (peri)vascular tissue induced by sunlight and paraquat.
In this study we exposed variegated leaves of Pelargonium zonale to strong sunlight (>1100μmolm-2s-1of photosynthetically active radiation) with and without paraquat (Pq), with the aim to elucidate the mechanisms of H2O2regulation in green and white tissues with respect to the photosynthetically-dependent generation of reactive oxygen species (ROS). Sunlight induced marked accumulation of H2O2in the apoplast of vascular and (peri)vascular tissues only in green sectors. This effect was enhanced by the addition of Pq. In the presence of diphenyl iodide, an NADPH oxidase inhibitor, H2O2accumulation was abolished. Distinct light-induced responses were observed: in photosynthetic cells, sunlight rapidly provoked ascorbate (Asc) biosynthesis and an increase of glutathione reductase (GR) and catalase activities, while in non-photosynthetic cells, early up-regulation of soluble ascorbate peroxidase, dehydroascorbate reductase (DHAR) and GR activities was observed. Paraquat addition stimulated DHAR and GR activities in green sectors, while in white sectors activities of monodehydroascorbate reductase, DHAR and class III peroxidases, as well as Asc content rapidly increased. Differential antioxidative responses in the two tissues in the frame of their contrasting metabolisms, and the possible role of (peri)vascular H2O2in signaling were discussed.
Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia. Electronic address: marija@imsi.rs.
Marija
M
Vidović
Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia. Electronic address: filkis14@hotmail.com.
Filis
F
Morina
Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11080 Belgrade, Serbia. Electronic address: ljprokic@agrif.bg.ac.rs.
Ljiljana
L
Prokić
Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia. Electronic address: soonjam@gmail.com.
Sonja
S
Milić-Komić
Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia. Electronic address: bokazivanovic@yahoo.com.
Bojana
B
Živanović
Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia. Electronic address: sonjavel@imsi.rs.
Sonja Veljović
SV
Jovanović
D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D010269:Paraquat / Q000633:toxicity*; D031316:Pelargonium / Q000187:drug effects* / Q000378:metabolism* / Q000528:radiation effects; D010544:Peroxidases / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000528:radiation effects; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D058526:Plant Vascular Bundle / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D013472:Sunlight
D000975:Antioxidants; D006861:Hydrogen Peroxide; D010544:Peroxidases; D002374:Catalase; D005978:Glutathione; D010269:Paraquat; D001205:Ascorbic Acid
Abscisic acid; Ascorbate-glutathione cycle; Hydrogen peroxide; Paraquat; Strong light; Variegated plants