MicroRNA Roles in Cotton Fiber Initiation and Early Development

Cotton fiber development is a fundamental biological process; investigating cotton fiber initiation and development provides a unique window into the regulation of cell differentiation, cellulose biosynthesis, and further increasing cotton fiber quality and yield. For several decades, a great deal of research has been aimed at elucidating the underlying molecular pathways. Nevertheless, the mechanisms by which cotton fiber differentiates and develops remains unclear. In our previous studies, we found that microRNAs (miRNAs) are differentially expressed among cotton fiber and other tissues. Comparing the miRNA expression profiles based on deep sequencing technology, we found that both conserved and novel miRNAs have unique pattern in cotton developing ovule. To further test the potential role of miRNAs during cotton fiber development, we selected 58 miRNAs and profiled their expression in fiber with different development stages (from -2 DPA to 20 DPA) in both wild type and fibreless mutants. Using transgenic, RNAi and genome editing technologies show that overexpression and knockout/knockdown of an individual miRNAs affected cotton fiber development and further affect cotton fiber length and quality.