Abstract
We have been investigating molecular mechanisms underlying plant development with temperature-sensitive mutants of Arabidopsis thaliana that are defective in organogenesis in vitro. One of these mutants, srd2 is characterized by the severe temperature sensitivity for hypocotyl dedifferentiation and neoformation of apical meristems. The SRD2 gene product shares sequence similarity with human SNAP50, a subunit of protein complex involved in transcription of small nuclear RNAs (snRNAs). The SRD2 function as an activator of snRNA transcription has been demonstrated by several lines of experiments.
snRNAs guide fundamental RNA processing/modification events including pre-mRNA splicing. As these functions of snRNAs are essential to cell activities, their transcription has been considered static and constitutive. However, our analysis of the srd2 mutant and the SRD2 gene showed that snRNA expression is dynamically controlled by SRD2 during development and that the dynamism of snRNA expression is important for particular aspects of development.
