Analysis of RID2, a Novel Nucleolar Factor of Arabidopsis Involved in Pre-rRNA Processing

Abstract

rid2 is a temperature-sensitive mutant of Arabidopsis that is defective in the initial process of root and callus formation, and therefore is expected to serve as a useful tool for studying dedifferentiation and reactivation of cell division. rid2 is also characterized by enlargement of the nucleolar cavity at the restrictive temperature, which directed our attention to the relationship between RID2 and nucleoli. We analyzed processing of pre-rRNAs, the main function of nucleoli, and showed that it is significantly impeded in the rid2 mutant. Analysis with RID2::GFP indicated that the RID2 protein is abundant in nucleoli.
For a genetic approach to understanding the action mechanism of RID2, we isolated a suppressor mutant of rid2, sriw1. Chromosomal mapping and genome sequencing detected a base substitution in At5g09330, which encodes a putative NAC transcription factor, of the sriw1 genome possibly responsible for suppression of rid2.