REDOX ENZYMES INVOLVED IN ARABIDOPSIS THALIANA (L.) HEYNH. SEEDLING RESPONSE TO COLD PLASMA TREATMENT OF SEEDS

Successful seed germination and seedling establishment are critical steps in agricultural production and in the maintenance of natural ecosystems. Seed treatment with cold plasma (CP), is an emerging eco-agricultural technology that has potential application for enhancement of plant growth and adaptation. In addition to sterilization effect, treatment of seeds with CP has been shown to have effect on a broad spectrum of plant development and physiological processes. Although the body of information on the biological effects of the CP is growing, the complex biological mechanisms involved in the plant response remains vague. The objective of this study was to assess role of reactive oxygen species (ROS) producing and redox balance regulating enzymes in response of the model plant Arabidopsis thaliana (L.) Heynh. to the seed treatment with atmospheric pressure dielectric barrier discharge plasma source. Seeds of A. thaliana Columbia ecotype wild-type (Col-0) and gene knockout mutant lines of ROS producing enzymes NADPH oxidase AtRbohB and AtRbohF and enzymes involved in maintenance of the cellular redox balance, AtAPXI and AtCAT2, were used in the study. Seeds were treated for 1.5 or 3.0 min at 3 mm distance from the CP source at 60-80% air humidity and stored for 7 days at 25 °C after the treatment. The significant changes in root length was observed for the 2 day old seedlings of Col-0, AtRbohB, AtRbohF and AtCAT2 germinated from the seeds treated for 3 min. AtRbohF showed an enhanced (~6 % compared to control) root growth response similar to that of the wild-type genotype, meanwhile the length of roots was reduced for the AtRbohB and AtCAT2 mutants (20 % and 10 %, respectively). In contrast to the effect observed for the roots, 3 min CP treatment had stimulating effect on hypocotyl development of the AtAPX1 mutant (~7 %). Meanwhile hypocotyls of the AtRbohF and AtCAT2 were shorter compared to control (9 % and 23 %, respectively). Hypocotyls of the Col-0 and AtRbohB mutant showed no response to CP treatment. The analysis confirmed that the redox enzymes play essential role in A. thaliana seedling phenotype formation in response to CP treatment and the effect could be linked to the role of ROS in seed germination and seedling organ development.