title: O2- activates leaf injury, ethylene and salicylic acid synthesis, and the expression of O3-induced genes in O3-exposed tobacco.
abstract: O3 is the major component of photochemical oxidants and gives rise to visible injuries on plant leaves. In O3-exposed plants, O2- is produced before the formation of the injury, but the role that O2- plays in plant response to 03 exposure is still unknown. To clarify its role, we observed the behavior of plants during O3 exposure after pretreatment with tiron, which is an O2- scavenger. When tiron-pretreated tobacco cv. Bel W3 was exposed to O3, leaf damage was attenuated. In O3-exposed tobacco, tiron inhibited increases in the levels of ethylene and salicylic acid, which promote leaf injury. Tiron pretreatment also suppressed increases in the expression of O3-induced genes. These results suggest that O2- is involved in many plant responses induced by O3 exposure. Bel B, a tobacco cultivar that is genetically related to Bel W3, is reported to be more resistant to O3 than Bel W3, but the reason for this difference is unclear. We investigated the differences between the responses of Bel B and tiron-pretreated Bel W3 to O3 exposure, and we discuss the reasons for the resistance to O3 by comparing the phenotype of Bel B with that of tiron-pretreated Bel W3.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ogawa
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Nakajima
authors.forename: Masanori
authors.initials: M
authors.lastname: Tamaoki
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Aono
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kubo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kamada
authors.forename: Hikaru
authors.initials: H
authors.lastname: Saji
mesh_terms: D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004798:Enzymes / Q000187:drug effects / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism*; D007700:Kinetics; D010126:Ozone / Q000494:pharmacology*; D010935:Plant Diseases; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D010940:Plant Proteins / Q000187:drug effects / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D013481:Superoxides / Q000494:pharmacology*; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D018744:DNA, Plant; D004798:Enzymes; D005030:Ethylenes; D010940:Plant Proteins; D013481:Superoxides; D010126:Ozone; C036216:ethylene; D020156:Salicylic Acid