Expression of glutamate dehydrogenase genes in Arabidopsis thaliana depends on the redox state of plastoquinone pool

Key Message Expression of Arabidopsis glutamate dehydrogenase genes during light-to-dark and dark-to-light shifts depends on chloroplast electron transport chain redox state rather than reactive oxygen species or glucose content. Expression of Arabidopsis thaliana glutamate dehydrogenase genes is very low in the light and high in the dark. The molecular signals and mechanisms that provide the light-dependent glutamate dehydrogenase genes regulation remain unknown. The aim of this work was to study a role of redox signals which occur during light shifts in the regulation of the glutamate dehydrogenase genes expression. Using photosynthetic electron transport inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl benzoquinone (DBMIB) we demonstrate that transcript levels of the GDH1 and GDH2 genes in Arabidopsis leaves change in accordance with a redox state of plastoquinone pool: they are low when it is highly reduced and high when it is oxidized. Hydrogen peroxide or high light treatment did not result in decreasing of GDH1 or GDH2 expression, so reactive oxygen species cannot be the signals that reduce expression of these genes during dark-to-light shifts. There was no significant difference between the glucose content in the leaves of plants treated with DCMU and the plants treated with DBMIB, so glucose is not the only or the main factor that regulates expression of the studied genes. We presume that expression of Arabidopsis GDH1 and GDH2 genes depends on the plastoquinone pool redox state.