Spatiotemporal transcriptome and metabolome landscapes of cotton fiber during initiation and early development.

Cotton fibers are single cells that develop from the epidermal cells in the outer integument of developing seeds. The processes regulating fiber cell development have been extensively studied; however, the spatiotemporal transcriptome and metabolome profiles during the early stages of fiber development remain largely unknown. In this study, we profile the dynamics of transcriptome and metabolome during the early stages of cotton fiber cell development using a combination of spatial transcriptomic, single-cell transcriptomic, and spatial metabolomic analyses. We identify the key genes (e.g., DOX2, KCS19.4, BEE3, and HOS3.7) and metabolites (e.g., linoleic acid, spermine, spermidine, and α-linolenic acid) that may regulate the early development of fiber cells. Finally, knockdown and gain-of-function analyses identify the crucial role of GhBEE3/Gh_A09G062900 in cotton fiber initiation. We also construct a publicly accessible website ( https://cotton.cricaas.com.cn/ovule/ ) for visualization of the spatiotemporal gene expression in cotton, providing a reference dataset for further studies on cotton fiber development.