title: Temporal dynamics of the cellular events in tobacco leaves exposed in São Paulo, Brazil, indicate oxidative stress by ozone.
abstract: Nicotiana tabacum 'Bel-W3' is widely used as an ozone bioindicator species, showing typical necrosis preceded by microscopic markers of oxidative stress. This study aimed to follow the development of symptoms in tobacco exposed in São Paulo highlighting the temporal dynamics of the cellular events. Leaves with and without necrosis were processed according to standard techniques for anatomical analyses. Leaves from the site with higher SUM00 presented thinner palisade parenchyma, fewer layers of spongy parenchyma, higher stomatal density, clusters of vessel elements in the midrib, erosion of cuticular waxes and stomatal damage. The sequence of microscopic events from the third day of exposure were condensation of the cytoplasm in parenchyma tissue, sinuosity of anticlinal walls, pectinaceous cell wall protrusions, chromatin condensation and changes in chlorophyll autofluorescence. On the 14th day of exposure, these events finally led to cell death in the palisade parenchyma and necrosis on the leaf. The markers observed indicated oxidative stress caused by ozone.
authors.affiliation: Instituto de Botânica, Núcleo de Pesquisa em Anatomia, Caixa Postal 68041, CEP 04045-972, São Paulo, SP, Brazil, andreanvpedroso@gmail.com.
authors.forename: Andrea Nunes Vaz
authors.initials: AN
authors.lastname: Pedroso
authors.forename: Edenise Segala
authors.initials: ES
authors.lastname: Alves
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D001938:Brazil; D016923:Cell Death / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D004784:Environmental Monitoring; D007700:Kinetics; D008856:Microscopy, Fluorescence; D009336:Necrosis; D018384:Oxidative Stress / Q000187:drug effects*; D010126:Ozone / Q000032:analysis / Q000633:toxicity*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects; D012621:Seasons; D014026:Nicotiana / Q000033:anatomy & histology / Q000166:cytology* / Q000187:drug effects*
chemical_list: D000393:Air Pollutants; D002734:Chlorophyll; D010126:Ozone