Comparative transcriptome analysis unravels distinct regulatory mechanisms governing fiber development in red silk cotton tree (Bombax ceiba).

Bombax ceiba a multipurpose tree that has recently garnered increasing interest due to the unique characteristics of its fibers, which hold promise for commercial textile applications. These fibers, derived from the inner epidermis of the fruit, are fine, lightweight, highly hollow, and exhibit excellent thermal insulation. Notably, they lack natural twist-an uncommon feature among plant-derived fibers. While this feature contributes to their distinctive structure, it also results in low tensile strength, rendering them unsuitable for conventional spinning processes and limiting their utility in textile manufacturing. In this study, we performed a comprehensive comparative transcriptome analysis to elucidate the regulatory mechanisms underlying fiber development in B. ceiba. Our findings revealed a distinct transcriptional landscape in the inner fruit epidermis, characterized by the enrichment of genes involved in hemicellulose and lignin biosynthesis. Furthermore, we identified a markedly reduced expression of genes associated with microtubule (MT) organization and orientation, which may influence the patterning of cellulose microfibril deposition and contribute to the suppression of fiber twist. These molecular signatures likely underpin the unique morphology and mechanical properties of B. ceiba fibers. Altogether, our study provides novel insights into the genetic and molecular basis of fiber development in B. ceiba, offering a foundation for future strategies aimed at improving fiber quality and expanding the industrial application of this and other natural fiber-producing species.