o-Phenylenediamine-induced DNA damage and mutagenicity in tobacco seedlings is light-dependent.
Of the three isomers of the aromatic amine phenylenediamine (PDA), only o-PDA, but not m- and p-PDA, induced DNA damage (as measured by the Comet assay), and somatic mutations in the leaves of the chlorophyll-deficient tester strain Nicotiana tabacum var. xanthi. With increasing light intensity (0, 30, 80 or 140 micromol m(-2)s(-1) photosynthetic photon fluence rate) during a 72h mutagenic treatment of tobacco seedlings, o-PDA-induced DNA damage and the yield of somatic mutations were significantly increased. The peroxidase inhibitor diethyldithiocarbamate (DEDTC) repressed o-PDA-induced DNA damage. The effect of light is caused by the light-dependent increase of peroxidase activity and the accumulation of hydrogen peroxide, which participate in the metabolic activation of the promutagen o-PDA to mutagenic product(s). In contrast, DNA damage induced by the direct-acting alkylating mutagen ethyl methanesulphonate was the same whether treatment was in the light or in the dark, and was not repressed by the peroxidase inhibitor DEDTC.
Gichner
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T
Institute of Experimental Botany, Academy of Sciences of Czech Republic, Na Karlovce 1a, 160 00 Prague 6, Czech Republic. gichner@ueb.cas.cz
Stavreva
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DA
Van Breusegem
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F
D002734:Chlorophyll / Q000172:deficiency / Q000235:genetics; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005020:Ethyl Methanesulfonate / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000378:metabolism; D008027:Light / Q000009:adverse effects*; D009153:Mutagens / Q000378:metabolism / Q000633:toxicity*; D009154:Mutation; D009195:Peroxidase / Q000378:metabolism; D010655:Phenylenediamines / Q000378:metabolism / Q000633:toxicity*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology; D010947:Plants, Toxic; D014026:Nicotiana / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects*
D009153:Mutagens; D010655:Phenylenediamines; D002734:Chlorophyll; C034193:1,2-diaminobenzene; D005020:Ethyl Methanesulfonate; D006861:Hydrogen Peroxide; D009195:Peroxidase