The SMC 5/6 complex along with cohesin and condensin is a member of the structural maintenance of chromosome (SMC) protein family. In yeast and mammals, this complex is engaged in DNA double strand break repair, genome stability, meiotic synapsis and recombination. In plants, the function of SMC5/6 remains enigmatic. Therefore, we analyzed the crucial δ-kleisin component NSE4 of the SMC5/6 complex in the model plant Arabidopsis thaliana. We identified and characterized two candidate genes - Nse4A and Nse4B. The knock-out of the Nse4A gene is lethal for the plant. Gene expression analyses demonstrated Nse4A expression across different tissue types, whereas Nse4B expression was undetectable or limited to generative tissue. To characterize the dynamics and localization of SMC5/6 complex components, we generated specific antibodies and transgenic fluorescence protein lines for NSE3, NSE4A and SMC5. Thus, we found the presence of these subunits in euchromatin of A. thaliana nuclei. The analysis of NSE4A::GFP and SMC5::EYFP lines revealed also the labeling of somatic nuclei.