Fig. 4

The rhythmic growth regulation of fiber cells. a–c The qRT-PCR of GhRALF1 expression (a), fiber length dynamic (b), and apoplastic pH (c) for the fiber cells across 0–2 DPA. Night and day are shown in grey and white, respectively. Dotted circles highlight the fast elongation episodes of fiber growth. Big and small triangles indicate the strong and weak expression peaks. d The schematic illustration for diurnal RNA-seq for the OI protoplasts of ovules. e The diurnal rhythmic expression of the genes for the OI protoplast cells in WT and fl across − 2 to 2 DPA. The fold changes of gene expression heatmap (left) and significance of differential expression (DE) (middle) between neighboring time points, and gene expression level in each cluster for scRNA-seq data (right) were shown. The genes were split into four groups according to their expression pattern in the diurnal RNA-seq data. f The enriched top 10 GO terms of biological processes for N1 group in e. g–j The qRT-PCR validations for the expressions of core-clock genes (g, h) and fiber-associated genes (i, j) under normal day-night (day/night) and continuous light (day/day) conditions. Night and day are shown in grey and white, respectively