title: Radial expansion of root cells and elongation of root hairs of Arabidopsis thaliana induced by massive doses of gamma irradiation.
abstract: Radial expansion of root cells and elongation of root hairs were induced within 3 d of a massive dose (3 kGy) of gamma irradiation to Arabidopsis thaliana. Because treatment with the antioxidant n-propyl gallate before irradiation suppressed these changes, gamma irradiation partially rescued the rhd2 mutant (defective in NADPH oxidase); the superoxide-generating reagent paraquat induced similar root morphogenesis. These responses appeared to be induced by the active oxygen species (AOS) generated by water radiolysis. Ethylene production was induced immediately after gamma irradiation and reached a steady level after about 2 h. Addition of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid partly induced a similar expansion of root cells and elongation of root hairs. Addition of an inhibitor of ethylene biosynthesis, aminoethoxyvinylglycine, before gamma irradiation completely suppressed the formation of abnormal structures. These results suggest that the AOS is involved in the root morphological changes through the ethylene biosynthesis induced by gamma irradiation in Arabidopsis.
authors.affiliation: Department of Molecular Genetics, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602 Japan. nagatat@nias.affrc.go.jp
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Nagata
authors.forename: Setsuko
authors.initials: S
authors.lastname: Todoriki
authors.forename: Shoshi
authors.initials: S
authors.lastname: Kikuchi
mesh_terms: D017360:Arabidopsis / Q000528:radiation effects* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism*; D005720:Gamma Rays; D007210:Indoleacetic Acids / Q000378:metabolism; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D019255:NADPH Oxidases / Q000235:genetics; D018517:Plant Roots / Q000528:radiation effects* / Q000648:ultrastructure; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005030:Ethylenes; D007210:Indoleacetic Acids; D017382:Reactive Oxygen Species; C036216:ethylene; C473291:Rhd2 protein, Arabidopsis; D019255:NADPH Oxidases