Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an enzyme widely involved in glycolysis in animal cells and in non-metabolic processes, including apoptosis and the regulation of gene expression. GAPDH is a ubiquitous protein that plays a pivotal role in plant metabolism and handling of stress responses. However, its function in plant stress resistance remains unknown. Identification and systematic analysis of the GAPDH family in Populus deltoides (P. deltoides) have not been performed. Bioinformatics methods were used to analyze the physicochemical characteristics, structural characteristics, phylogenetic relationships, gene structure, motif analysis, and expression of GAPDH gene family members in P. deltoides. We identified 12 GAPDH members in P. deltoides. Five types of PdGAPDH were identified: GAPA, GAPB, GAPC1, GAPC2, and GAPCp. PdGAPDH genes were differentially expressed in leaves, stems, and roots of 1-year-old poplar seedlings. PdGAPDH gene transcripts showed that PdGAPDH2 and PdGAPDH4 were highly expressed in the leaves. In the roots, seven genes—PdGAPDH01, PdGAPDH05, PdGAPDH06, PdGAPDH07, PdGAPDH08, PdGAPDH09, and PdGAPDH12—showed significantly high expression levels. PdGAPDH02, PdGAPDH03, PdGAPDH04, and PdGAPDH11 showed decreased expression under drought conditions and recovered after re-watering. These results lay the foundation for further studies on the drought stress mechanisms of P. deltoides.

GAPDH Gene Family in Populus deltoides: Genome-Wide Identification, Structural Analysis, and Expression Analysis Under Drought Stress