Abstract
We have been investigating molecular mechanisms of organogenesis in vitro with temperature-sensitive mutants of Arabidopsis thaliana. Of these mutants, srd2 and rid1 were characterized by the temperature sensitivity of hypocotyl dedifferentiation and meristem neo-formation. Studies with the srd2 mutant at the molecular level have revealed that SRD2 regulates snRNA level by activating snRNA transcription and that this is a vital part of hypocotyl dedifferentiation.
The RID1 gene was identified as encoding a putative DEAH-box RNA helicase. Sequence analysis showed a high similarity of RID1 to budding yeast Prp22, which is known to participate in pre-mRNA splicing. This implies that the major role of SRD2-mediated activation of snRNA transcription in organogenesis is the increase of pre-mRNA splicing capacity. In favor of this hypothesis, by RT-PCR analysis, we found that the srd2 mutation affects splicing patterns of several genes during hypocotyl dedifferentiation. More comprehensive analysis of splicing patterns in srd2 and rid1 is in progress with the whole genome tiling array.
