title: Could the differences in O(3) sensitivity between two poplar clones be related to a difference in antioxidant defense and secondary metabolic response to O(3) influx?
abstract: Increasing global background concentrations of tropospheric ozone (O(3)) are expected to affect both crops and forest ecosystems negatively. The phytotoxic effects of O(3) are mainly associated with the O(3)-induced production of reactive oxygen species (ROS) in excess of the ability of the plant to maintain ROS below the tolerance threshold. It is the balance between O(3) uptake and cellular antioxidant potential that determines O(3) effects on vegetation. The greater sensitivity to ambient O(3) exposure (60 nl l(-1) O(3), 15 days, 5 h a day) of poplar clone Eridano (Populus deltoides x maximowiczii) compared with clone I-214 (P. x euramericana) was reflected in a lower photosynthetic efficiency, higher stomatal conductance and hydrogen peroxide (H(2)O(2)) accumulation and more pronounced leaf tissue membrane injury in Eridano than in I-214. We checked if the differences in clonal responses to O(3) fumigation were related to differing capacities for antioxidant defense and phenylpropanoid metabolism and found that the increases in foliar ascorbate and phenolic concentrations and phenylpropanoid metabolism in Eridano were insufficient to counteract H(2)O(2) accumulation and the consequent oxidative stress. This was probably because the higher influx of O(3) into Eridano leaves compared with I-214 leaves resulted in a lower potential detoxification capacity per unit of O(3) influx.
authors.affiliation: Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, I-56127 Pisa, Italy. dibaccio@sssup.it
authors.forename: Daniela
authors.initials: D
authors.lastname: Di Baccio
authors.forename: Antonella
authors.initials: A
authors.lastname: Castagna
authors.forename: Elena
authors.initials: E
authors.lastname: Paoletti
authors.forename: Luca
authors.initials: L
authors.lastname: Sebastiani
authors.forename: Annamaria
authors.initials: A
authors.lastname: Ranieri
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D005453:Fluorescence; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010126:Ozone / Q000378:metabolism*; D010636:Phenols / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D054046:Plant Stomata / Q000378:metabolism; D032107:Populus / Q000201:enzymology / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D010636:Phenols; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D010126:Ozone; D006861:Hydrogen Peroxide; D005978:Glutathione; D001205:Ascorbic Acid