Abstract
We have been investigating molecular mechanisms of organogenesis in vitro with temperature-sensitive mutants of Arabidopsis thaliana. One of these mutants, srd2 was characterized by the temperature sensitivity of dedifferentiation and meristem neo-formation. Studies with this mutant at the molecular level have revealed that SRD2 regulates snRNA level by activating snRNA transcription and that this is a vital part of organogenesis.
rid1 (root initiation defective 1) was originally isolated as being temperature-sensitive for adventitious root formation. Phenotypic analysis in tissue culture indicated that rid1 shares many characteristics with srd2. Chromosome mapping followed by sequence analysis and allelism test strongly suggested that the RID1 gene is At1g26370. The predicted product of At1g26370 is similar in sequence to yeast Prp22, a DEAH-box RNA helicase involved in pre-mRNA splicing. These results imply that the major role of SRD2-mediated snRNA transcription activation in organogenesis is the up-regulation of pre-mRNA splicing activity.
