Chromatin accessibility map of rice root tips at single-cell resolution [scATAC-seq]

Background: Single-cell reconstruction of gene regulatory programs provides an important tool to understand the cellular phenotypic variation in complex tissues and their response to endogenous and environmental stimuli. While the single-cell transcriptomes of several plant organs have been elucidated, the underlying chromatin landscapes remain largely unknown. Results: To comprehensively delineate chromatin accessibility during root development of an important crop, we applied single-cell ATAC-seq to 46,758 cells from rice root tips under normal and heat stress conditions. Our data revealed cell-type-specific accessibility variance across most of the major cell types and allowed us to identify sets of transcription factors which associate with accessible chromatin regions (ACRs). Using root hair differentiation as a model, we demonstrate that chromatin dynamics and gene expression dynamics during cell type differentiation correlate in pseudotime analyses. In addition to developmental trajectories, we describe chromatin responses to heat, and identify cell type specific accessibility changes to this key environmental stimulus. Conclusions: Our work provides a framework for the integrative analysis of regulatory dynamics in an important plant organ at single-cell resolution. Overall design: Single-cell ATACseq of rice root tips