One additional histone deacetylase and 2 histone acetyltransferases are involved in cellular patterning of Arabidopsis root epidermis.

The cellular patterning of Arabidopsis root epidermis is a well-characterized system for study of how single-layered cells are arranged in a particular spatial order. Previously, we found that histone acetylation plays an important role in regulating epidermal differentiation by relaying positional information. To investigate the underlying mechanisms, we screened all available mutants of both HDAC and HAT families. Analyses of mutants of HDAC family members revealed that among single mutants, only HDA6, HDA18 and HDA19 exhibited ectopic H cells at the N position. Similarly, among HAT family members, only single mutants for GCN5 and HAF2 exhibited altered epidermal phenotypes, which were unexpectedly similar to the phenotypes observed in HDAC mutants. Based on these results, together with the previous findings regarding the regulatory mechanisms of HDA18 and HDA6, we proposed that homeostasis of histone acetylation is important for robustness of the regulatory network responsible for the cellular patterning of the Arabidopsis root epidermis.