The cotton fiber transcriptome

Among the longest cell types known in plants, cotton fibers are economically important seed trichomes that provide a unique single‐celled model system for studying fundamental biological processes. Functional genomic approaches have served to characterize dynamic changes to the cotton fiber transcriptome in response to developmental signals that control fiber morphogenesis at the level of a single cell. The genetic complexity of the fiber transcriptome is very high and accounts for as much as 45–50% of the genes in the cotton genome. In addition to a large diverse group of constitutively expressed genes, expression profiling of the transcriptome revealed two developmentally regulated stage‐specific expression patterns that define rapid cell elongation during primary cell wall (PCW) synthesis relative to secondary cell wall biogenesis. In developing cotton fibers, many fiber genes involved in PCW synthesis and turgor‐driven cell expansion are differentially expressed in a manner that parallels the growth rate. Characterization of the cotton fiber transcriptome has immediate applications in agricultural biotechnology and molecular breeding programs geared toward the genetic improvement of yield and fiber quality.