Elongator Is Required for Root Stem Cell Maintenance by Regulating Transcription.

() is essential for stem cell maintenance and radial patterning in Arabidopsis () roots, but how its expression is regulated is unknown. Here, we report that the Elongator complex, which consists of six subunits (ELP1 to ELP6), regulates the transcription of Depletion of Elongator drastically reduced expression and led to defective root stem cell maintenance and radial patterning. The importance of the nuclear localization of Elongator for its functioning, together with the insensitivity of the mutant to the transcription elongation inhibitor 6-azauracil, and the direct interaction of the ELP4 subunit with the carboxyl-terminal domain of RNA polymerase II, support the notion that Elongator plays important roles in transcription elongation. Indeed, we found that ELP3 associates with the premessenger RNA of and that mutation of Elongator reduces the enrichment of RNA polymerase II on the gene body. Moreover, Elongator interacted in vivo with SUPPRESSOR OF Ty4, a well-established transcription elongation factor that is recruited to the locus. Together, these results demonstrate that Elongator acts in concert with SUPPRESSOR OF Ty4 to regulate the transcription of .