Deep sequencing of small RNAs in the trasngenic wild type plant and the IWR1-type transcription factor mutant, dms4

Full title: Deep sequencing of small RNAs in the trasngenic wild type plant (contains trigger and silencer transgenes) and the IWR1-type transcription factor mutant, dms4 RNA-directed DNA methylation (RdDM) in plants requires two RNA polymerase II (PolII)-related RNA polymerases named PolIV and PolV. A genetic screen designed to reveal factors important for RdDM in a developmental context in Arabidopsis identified DEFECTIVE IN MERISTEM SILENCING 4 (DMS4). Unlike other mutants defective in RdDM, dms4 mutants have a pleiotropic developmental phenotype.DMS4 is similar to yeast IWR1, a conserved putative transcription factor that interacts with PolII subunits. In the transgenic system studied, mutations in DMS4 directly or indirectly affect PolIV-dependent secondary siRNAs, PolV-mediated RdDM, PolV-dependent synthesis of intergenic noncoding RNA, and expression of many PolII-driven genes. These data suggest that DMS4 may be a regulatory factor for multiple RNA polymerases, thus explaining its diverse roles in the plant. Overall design: Examination of siRNA abundance in the trasngenic wild type plant (contains trigger and silencer transgenes) and the dms4 mutant.