Transcript elongation factors: shaping transcriptomes after transcript initiation.

Elongation is a dynamic and highly regulated step of eukaryotic gene transcription. A variety of transcript elongation factors (TEFs), including modulators of RNA polymerase II (RNAPII) activity, histone chaperones, and histone modifiers, have been characterized from plants. These factors control the efficiency of transcript elongation of subsets of genes in the chromatin context and thus contribute to tuning gene expression programs. We review here how genetic and biochemical analyses, primarily in Arabidopsis thaliana, have advanced our understanding of how TEFs adjust plant gene transcription. These studies have revealed that TEFs regulate plant growth and development by modulating diverse processes including hormone signaling, circadian clock, pathogen defense, responses to light, and developmental transitions.