48-Hour and 24-Hour Time-lapse Single-nucleus Transcriptomics Reveal Cell-type specific Circadian Rhythms in Arabidopsis.

Functional circadian clock is critical to the adaptation and survival of organisms. In land plants, the comprehensive profiling of circadian gene expression at the single-cell level is largely unknown partly due to the challenges in obtaining precisely-timed single cells embedded within cell walls. To bridge this gap, we employ time-lapse single-nucleus RNA sequencing (snRNA-seq) on Arabidopsis seedlings collected over a 48-hour window at 4-hour intervals, as well as over a 24-hour day at 2-hour intervals, yielding a total of over 77,142 and 130,000 nuclei. Here, we find that four cell clusters in the shoot share a coherent rhythm, while around 3000 genes display cell-type specific rhythmic expression. Our analysis indicates that genes encoding circadian regulators oscillate in multiple cell types, and the majority of them are well-documented core clock genes, suggesting the snRNA-seq circadian data could be used to identify more clock components oscillating in a cell-autonomous way. We identify ABF1 as a circadian regulator, whose overexpression and shortens the circadian period. Our data provides a comprehensive resource for plant circadian rhythmicity at the single-cell level (hosted at https://zhailab.bio.sustech.edu.cn/sc_circadian ).