The role of САТ2 isoenzyme during early heat stress response of Arabidopsis thaliana

  • І. М. Буздуга Yuri Fedkovych National University of Chernivtsi Ukraine, 58012, Chernivtsi, Kotsubynski str., 2
  • Р. А. Волков Yuri Fedkovych National University of Chernivtsi Ukraine, 58012, Chernivtsi, Kotsubynski str., 2
  • І. І. Панчук Yuri Fedkovych National University of Chernivtsi Ukraine, 58012, Chernivtsi, Kotsubynski str., 2

Abstract

Aim. Denaturation of proteins and enhanced generation of reactive oxygen species (ROS) cause cellular injury upon increased temperatures. The aim of the study was to clarify the specific protecting role of the catalase isoform CAT2 of Arabidopsis thaliana upon moderate (37 °С) and severe (44 °С) heat stress. Methods. Leaves of wild type and КО-Cat2 knock-out mutant plants were subjected to heat treatment. Changes in catalase activity and isoenzyme patterns were evaluated. Results. It was found that upon optimal cultivation conditions the total CAT activity is about two times lower in leaves of КО-Cat2 knock-out mutant comparing to wild type plants. Two isoenzymes, CAT2 and CAT3, are expressed in leaves of wild type plants, whereas in КО-Cat2 plants not only CAT3, but also CAT1 isoenzyme was detected. During heat treatment, CAT activity remained stable in wild type leaves, whereas in the mutant it was increased after 2 hours of moderate heat treatment and decreased after 1 and 4 hours of moderate and severe heat treatment. The lowest level of CAT activity was found during recovery after severe heat stress. Conclusions. САТ2 is a thermostable enzyme that is essential for hydrogen peroxide scavenging and limitation of oxidative damage in leaves upon heat stress. The lack of this isoenzyme in the knock-out mutant results in activation of CAT1. Nevertheless, the total CAT activity remains decreased. Increased protein carbonylation upon severe heat stress and defects during post-stress recovery detected in the mutant demonstrate that the loss of САТ2 can not be compensated by the activation of САТ1.

Keywords: Arabidopsis thaliana, catalase, hydrogen peroxide, heat stress, knock-out mutants.