LCM and RNA-seq analyses revealed roles of cell cycle and translational regulation in early stages of cotton fiber cell development
BackgroundCotton fibers provide a powerful model for studying cell differentiation and elongation. Each cotton fiber is a singular and elongated cell derived from epidermal-layer cells of a cotton seed. Efforts to understand this dramatic developmental shift have been impeded by the difficulty of isolating fiber cells from epidermal cells.ResultsHere we employed laser-capture microdissection (LCM) to separate these cell types. RNA-seq analysis revealed transitional differences between the fiber
... s between the fiber and epidermal-layer cells at 0 or 2 days post anthesis. Specifically, down-regulation of putative cell cycle genes was coupled with upregulation of ribosome biosynthesis and translation-related genes, which may suggest their respective roles in fiber cell initiation and elongation. Indeed, the amount of fibers in cultured ovules was increased by cell cycle progression inhibitor, Roscovitine, and decreased by ribosome biosynthesis inhibitor, Rbin-1. Moreover, many phytohormone-related genes were upregulated in the ovules and down-regulated in the fibers, suggesting their spatial-temporal effects on fiber cell development. Key cell cycle regulators were predicted to be epialleles, and MYB-transcription factor related genes displayed expression divergence between fibers and ovules, implying their effects on fiber traits.ConclusionsWe revealed that fiber cell initiation is accompanied by cell cycle arrest coupled with active ribosome biosynthesis, spatial-temporal regulation of phytohormones and expression divergence between MYB transcription factor genes. These valuable genomic resources and molecular insights will help develop breeding and biotechnological tools to improve cotton fiber production.