Recent advances in genetic control of fiber length in upland cotton

Cotton fiber quality-defined by length, strength, and fineness-directly influences the commercial value of textile products, with fiber length being one of the most critical parameters in industrial procurement. In upland cotton (Gossypium hirsutum), fiber development occurs through four overlapping stages, of which the elongation phase (2-20 d post-anthesis, DPA) is pivotal for determining final fiber length. Recent studies have identified a diverse set of genes regulating fiber elongation via distinct molecular mechanisms, categorized into six functional classes: Phytohormone-associated genes; transcription factor-associated genes; cellulose-, lignin-, and sucrose-associated genes; lipid-associated genes; cytoskeleton-associated genes; and other functionally diverse genes. By synthesizing their roles and hierarchical interactions, this review constructs comprehensive genetic networks governing fiber elongation. This work provides a molecular blueprint for precision breeding strategies to enhance cotton fiber length, offering actionable insights for breeding programs aimed at improving fiber quality.