Primary function of seryl-tRNA synthetase (SerRS) is attachment of serine to tRNASer preparing a foundation for successful protein biosynthesis. It is shown in this dissertation that cytosolic SerRS from plant Arabidopsis thaliana (L.) Heynh, also performs non-canonical functions by establishing so far the unknown interaction with protein BEN1 which is involved in metabolism of brassinosteroids, compounds important in cell stress response what potentially implicates involvement of SerRS in cell stress response. Furthermore, in vitro experiments showed that SerRS almost equally well catalyzes aminoacylation of bacterial and eukaryotic tRNASer substrates. Given the fact that the same behaviour was previously shown for monocot maize SerRS, it seems that plant SerRSs exibit unusually broad tRNASer specificity, unlike SerRSs from other organisms. Localization experiments under conditions of stable transformation in transgenic A. thaliana plants did not detect SerRS in the cell nucleus. Under transient transformation of A. thaliana protoplasts SerRS was detected in cell nucleus in 10-20 % of calls. Finally, statistically significant difference in root length of transgenic A. thaliana plants overexpressing SerRS in comparison with wild type was found under conditions of abiotic stress caused by ionic and osmotic stressors and cadmium in plants grown continuously on stress growth medium.