The GDSL esterase/lipase (GELP) family comprises a group of multifunctional hydrolases with broad substrate specificity and catalytic versatility, playing an essential role in plant growth and developmental processes. The GDSL lipase gene GhGELP23D from Gossypium hirsutum is highly expressed during cotton fiber elongation development. This study aims to investigate its function in plant cell elongation and provides references for the mechanism elucidation of GELP-mediated regulation of cell growth.

The GhGELP23D was cloned from upland cotton fibers. Bioinformatic analyses were performed to characterize its physicochemical properties, structural features, and phylogenetic relationships. The promoter region was analyzed with PlantCARE to identify putative cis-elements. Expression patterns were detected based on public transcriptomic data and RT-qPCR validation. A GUS reporter construct driven by the GhGELP23D promoter was generated to examine the tissue-specific expression of GhGELP23D in stably transformed Arabidopsis. Subcellular localization of GhGELP23D was determined through transient expression in Nicotiana benthamiana leaves. Transgenic Arabidopsis lines heterologously expressing GhGELP23D (GhGELP23D-OE) were obtained using the floral-dip method, and phenotypic analyses were conducted. Additionally, virus-induced gene silencing (VIGS) was employed to suppress GhGELP23D expression in cotton. Silencing efficiency was verified by RT-qPCR, and the resulting changes in fiber length were assessed in GhGELP23D-VIGS plants.

GhGELP23D encodes a 356-amino-acid protein that is stable, weakly basic, and hydrophilic, containing a typical signal peptide but no transmembrane domain. Transcriptomic analysis and RT-qPCR detection showed that GhGELP23D was highly expressed during cotton fiber elongation. Subcellular localization analysis revealed that GhGELP23D is predominantly localized to the extracellular space. Analysis of the GhGELP23D promoter indicated the presence of multiple cis-elements related to light responsiveness, hormone signaling, and stress response. Histochemical GUS staining showed that the GhGELP23D promoter can drive reporter gene expression in various Arabidopsis tissues, indicating broad tissue expression activity. Heterologous expression of GhGELP23D in Arabidopsis (GhGELP23D-OE) significantly enhanced plant growth and development, resulting in increased plant height and longer primary roots and root hairs. Furthermore, complementation of GhGELP23D in the mutant resulted in a pronounced recovery of primary root and root hair length similar to that of the wild type (WT). In cotton, the fiber length of GhGELP23D-VIGS lines was significantly reduced compared with that of empty-vector control plants, with an average decrease of approximately 13.14%.

GhGELP23D encodes an extracellular GDSL lipase that is highly expressed during the fiber elongation stage of upland cotton and plays an important role in plant cell elongation development.