Speaker: Kevin Potter, University of North Carolina - Chapel Hill, NSF Plant Genome Postdoc Fellow in the Kieber Lab

Title: Cytokinin modulates context-dependent chromatin accessibility through the type-B response regulators

Abstract: The phytohormone cytokinin regulates diverse aspects of plant growth and development, probably through context-dependent transcriptional regulation that relies on a dynamic interplay between regulatory proteins and chromatin. We employed the assay for transposase accessible chromatin with sequencing to profile changes in the chromatin landscape of Arabidopsis roots and shoots in response to cytokinin. Our results reveal differentially accessible chromatin regions indicative of dynamic regulation in response to cytokinin. These changes in chromatin occur preferentially upstream of cytokinin-regulated genes. The changes also largely overlap with binding sites for the type-B ARABIDOPSIS RESPONSE REGULATORS (ARRs), transcription factors that mediate the primary response to cytokinin. Furthermore, the type-B ARRs were found to be necessary for the changes in chromatin state in response to cytokinin. We also identified context-dependent responses by comparing root and shoot profiles. We have extended these results to rice and have also begun to explore the mechanisms that type-B ARRs employ to displace nucleosomes. These studies provide new insight into the dynamics between cytokinin and chromatin with regard to directing transcriptional programmes and how cytokinin mediates its pleiotropic effects.

Host: Erik Vollbrecht