[Collection of Arabidopsis thaliana mutants with altered sensitivity to oxidative stress inductors]. / Kollektsiia mutantov Arabidopsis thaliana s izmenennoi chuvstvitel'nost'iu k induktoram okislitel'nogo stressa.

Selective systems for screening Arabidopsis thaliana (L.) Heynh. mutants with altered sensitivity to the oxidative stress (OS) inductors norflurazon (NF), acifluorfen (AF), and plumbagin (PB) were developed and a collection of 28 mutants was obtained. Dwarf and necrotic forms predominated among the NF-tolerant mutants, while pigment mutants and those with changed root morphology prevailed among the AF-tolerant and PB-sensitive mutants, respectively. Genetic and biochemical analysis of certain mutants was performed; quantitative and qualitative changes in the content of superoxide dismutase and peroxidase isoforms have been revealed. These data, complemented by the data on the cross-tolerance (sensitivity) of the mutants to paraquat, indicate a correlation between tolerance to the OS inductors and the functions of antioxidant systems.

[The enzymatic activity of the antioxidant system in the ontogeny of mutant norflurazone-tolerant Arabidopsis thaliana]. / Izuchenie aktivnosti fermentov antioksidantnoi sistemy v ontogeneze mutantov Arabinopsis thaliana, tolerantnykh k norflurazonu.

The activities of superoxide dismutase and guaiacol-dependent peroxidase were studied in the ontogenesis of recessive homozygous mutants of Arabidopsis thaliana Heynh. le-2 and nfz24, which are characterized by two- to threefold increases in tolerance to the herbicide norflurazone. The mutants le-2 and nfz24 differed from the initial race Dijon in some phenotypic features, duration of ontogenetic stages, and dynamics of the superoxide dismutase and peroxidase activities in ontogenesis. A single treatment of plants with norflurazone induced an accelerated increase in the level of both enzymes in the mutants as compared to the wild type plants. Under the conditions of multiple treatment with norflurazone, the mutants le-2 and nfz24 displayed a higher tolerance to the bleaching effect of the herbicide and were characterized by a higher level of superoxide dismutase. The data obtained suggest that the superoxide dismutase and peroxidase activities are controlled by both ontogenetic factors and stress signals. Mutations in the lines le-2 and nfz24 increase sensitivity to a stress signal or increase efficiency of an adaptive response due to long-term maintenance of a high level of the antioxidant enzymes under the conditions of stress.