Genome-Wide Identification of Cotton ( spp.) Glycerol-3-Phosphate Dehydrogenase (GPDH) Family Members and the Role of in Response to Drought Stress.

Glycerol-3-phosphate dehydrogenase (GPDH) is a key enzyme in plant glycerol synthesis and metabolism, and plays an important role in plant resistance to abiotic stress. Here, we identified 6, 7, 14 and 14 GPDH genes derived from , , and , respectively. Phylogenetic analysis assigned these genes into three classes, and most of the genes within the family were expanded by whole-genome duplication (WGD) and segmental duplications. Moreover, determination of the nonsynonymous substitution rate/synonymous substitution rate () ratio showed that the GPDH had an evolutionary preference for purifying selection. Transcriptome data revealed that GPDH genes were more active in the early stages of fiber development. Additionally, numerous stress-related cis-elements were identified in the potential promoter region. Then, a protein-protein-interaction (PPI) network of in was constructed. In addition, we predicted 30 underlying miRNAs in . Functional validation results indicated that silencing diminished drought tolerance in the upland cotton TM-1 line. In summary, this study provides a fundamental understanding of the GPDH gene family in cotton, exerts a positive effect during drought stress and is potentially involved in stomatal closure movements.