Differential activity of catalase isoforms in Arabidopsis thaliana upon salt stress
Aim. The reasons for the broad distribution of multigene families in plant genomes are poorly understood to date. The aim of the current work was to investigate the specific roles of catalase isoforms during early response of Arabidopsis thaliana to salt stress. Methods. Rosettes of wild-type and Catalase 2 knock-out plants (КО-Cat2 homozygote knock-out strain SALK 057998) were treated with 50, 100 or 200 mM NaCl for 4 or 8 hours. Afterwards, catalase activity changes were evaluated. Results. It was found that the total catalase activity in КО-Cat2 leaves was about twofold lower than in wild-type. The activity of catalase in wild-type leaves decreased under 4-hour treatment with 50 and 100 mM NaCl and remained at control level during 200 mM NaCl treatment. Extending the treatment time to 8 hours resulted in elevation of catalase activity. In the KO-Cat2 plants the catalase activity increased above control levels while treated with 200 mM NaCl and remained unchanged in all other treatments. Conclusions. The activation of catalase is one of the early responses of Arabidopsis thaliana to salt stress. Isoforms of catalase are activated differently during the stages of stress response. A possible reason for the existence of several isoforms of CAT appears to be the impossibility to combine different regulatory signals, which are required for differential expression of this enzyme in response to various external factors, within one single promoter.
Key words: Arabidopsis thaliana, multigenic families, catalase isoforms, hydrogen peroxide, salt stress, knock-out mutants.