GLUTATHIONE REDUCTASE SIGNIFICANCE FOR IN VITRO SOMATIC EMBRYOGENESIS AND SALT STRESS RESPONSE OF DACTYLIS GLOMERATA L.
DENITSA TEOFANOVA, MIROSLAVA TERZIEVA, LYUBEN ZAGORCHEV*, MARIELA ODJAKOVA
Department of Biochemistry, Faculty of Biology, Sofia University St. Kliment Ohridski, 8 Dragan Tsankov blvd., Sofia, 1164, Bulgaria
*Corresponding author: lzagorchev@biofac.uni-sofia.bg
Keywords: glutathione, glutathione reductase, redox state, salt stress, somatic embryogenesis
Abstract: The non-protein thiol tripeptide glutathione and its corresponding disulfide represent a redox couple, which is essential for the maintenance of the intracellular redox state. It is involved in numerous physiological and developmental processes in plants, including somatic embryogenesis and abiotic stress response. Glutathione reductases, the enzymes, responsible for reduction of glutathione disulfide are crucial to sustain favorable intracellular redox environment and therefore, play a key role in the above-mentioned processes. The activity of glutathione reductase was investigated on different stages of somatic embryogenesis and different salt treatments (enhancing – 0.085 M and inhibitory – 0.17 M NaCl for its concentrations) in in vitro cultures of Dactylis glomerata L. To evaluate their role in the control of developmental processes and abiotic stress response, thiol disulfide reducing enzymes were investigated in assay, following the oxidation of NADPH and isoforms were determined after electrophoretic separation. The highest activity of glutathione reductase was detected on the 10th day of cultivation when pro-embryogenic masses were formed. Activity in high salt treated cultures was low during the whole cultivation period. Zymographic analysis revealed three different glutathione reductase isoforms that could use both NADPH and NADH and a single NADH-dependent isoform. Glutathione reductase was shown to be important for the process of somatic embryogenesis, probably by controlling the low molecular weight thiol redox status on different developmental stages.