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 nucleolus at the restrictive temperature. Our analyses revealed that RID2 encodes a methyltransferase-like protein, which was shown to localize mainly in the nucleolus, and that its function is required for pre-rRNA processing.
For a genetic approach to understanding the role of RID2, we isolated a suppressor mutant of rid2, sriw1. Sequencing analysis of the sriw1 genome detected a base substitution in a NAC transcription factor gene, At5g09330, which is possibly responsible for the suppressor phenotype. Interestingly, the sriw1 mutation also suppressed the defects of other mutants that are temperature-sensitive for callus initiation. These results suggest that SRIW1 occupies a key position in the regulation of cell proliferation.
