Arabidopsis thaliana Nuclear and cytoplasmic RNA factors in Arabidopsis thaliana We focus on Arabidopsis components of LSM complexes, decapping DCP1-2 proteins, 5'-3' exonucleases XRN and chosen components of the exosome complex of 3'-5' exonucleases. We perform functional analysis of these proteins by studying the consequences of their depletion on RNA level and stability in plant T-DNA insertion mutants and RNAi- or iRNAi- mutants using Northern, microarray and qRT-PCR analyses. We have shown that LSM proteins function in the cytoplasmic mRNA decay and in splicing of specific transcripts, whereas AtXRN2 exonuclease turned out to participate in early steps of rRNA processing. We plan to establish the contribution of the 3' and 5' mRNA degradation to general and specific (NMD, ARE- and DST-dependent) decay pathways and to identify cellular components that interact with RNA-quality systems in plants.