The role of the nucleolus in mRNA biogenesis in Arabidopsis

The eukaryotic nucleolus is a multifunctional nuclear compartment involved in transcription/processing of ribosomal RNAs and ribosomal subunit assembly, assembly and processing of RNA/RNPs and cellular functions like the cell cycle. In animals it is important in stress perception and responses. In plants, the presence of aberrant mRNAs and UPF2/3 in the nucleolus suggested that a role in NMD However, mRNA transcripts which contain retained introns (IR) are not subject to NMD and such transcripts represent the major class of aberrant mRNAs found in the nucleolus. That IR transcripts avoid the NMD machinery suggest that the nucleolus may have some function in identification or sequestration of these transcripts before they are exported. We wish to examine the role of the nucleolus in these various aspects of mRNA biogenesis in normal and stress conditions. We will examine the fate of various transcripts in the nucleolus of wild-type Arabidopsis and NMD mutant plants, the effect on distribution and export of mRNAs on disruption of specific components or the nucleolus to provide a model for the role of the nucleolus in mRNA production in plants.