title: Spatial patterns of senescence and development-dependent distribution of reactive oxygen species in tobacco (Nicotiana tabacum) leaves.
abstract: Senescence of tobacco leaves is distributed non-uniformly over a leaf blade. While photosynthetic competence and expression of photosynthesis-associated genes decline in interveinal areas of the leaf lamina with advancing age of the leaf, they are maintained at high levels in the tissue surrounding the veins. In contrast, expression of senescence-associated genes (SAG) was enhanced in both areas of the leaf blade. Accumulation of hydrogen peroxide was shown to precede the phase of senescence initiation in the veinal tissue. In the interveinal tissue, the level of hydrogen peroxide was increased with senescence progression and paralleled by an increase in the level of superoxide anions. It is hypothesized that the spatial differences in superoxide anions are important for the non-uniform down-regulation of photosynthesis-associated genes (PAG), while hydrogen peroxide is responsible for up-regulation of SAG.
authors.affiliation: Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Krakow, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Niewiadomska
authors.forename: Lisa
authors.initials: L
authors.lastname: Polzien
authors.forename: Christine
authors.initials: C
authors.lastname: Desel
authors.forename: Piotr
authors.initials: P
authors.lastname: Rozpadek
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Miszalski
authors.forename: Karin
authors.initials: K
authors.lastname: Krupinska
mesh_terms: D002374:Catalase / Q000378:metabolism; D016922:Cellular Senescence / Q000235:genetics / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D006861:Hydrogen Peroxide / Q000378:metabolism; D015151:Immunoblotting; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism; D014026:Nicotiana / Q000254:growth & development / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D013481:Superoxides; D006861:Hydrogen Peroxide; D002374:Catalase