Evolutionary characteristics of the GAPDH gene family and functional characterization of TaGAPDH5 in wheat.

BACKGROUND

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key glycolytic enzyme that also plays important roles in plant responses to abiotic stresses. However, the evolutionary relationships of the GAPDH genes among wheat species with different ploidy levels remain poorly understood, and the key TaGAPDH members involved in the drought response of wheat have yet to be identified.

RESULTS

In this study, we identified 5, 6, 13, and 19 GAPDH proteins in Triticum urartu, Aegilops tauschii, Triticum turgidum, and Triticum aestivum with different ploidy levels. All identified GAPDH proteins harbored the conserved Gp_dh_N and Gp_dh_C domains and were phylogenetically assigned to four subfamilies: GAPA, GAPB, GAPC, and GAPCp. Gene structure and conserved motif analyses indicated overall conservation of the GAPDH family but clear divergence among subfamilies, with Motif 13 emerging as a characteristic motif unique to GAPB. Cis-element prediction revealed that the promoters of TaGAPDH genes contain numerous putative cis-acting elements associated with responses to drought and light. Transcriptomic profiling further verified that TaGAPDH genes exhibited tissue-specific expression patterns and were actively responsive to drought stress. Expression trend correlation analysis of drought-responsive transcriptomic data suggested a potential regulatory association between TaMYB-7D and TaGAPDH5. Consistently, transient dual-luciferase assays showed that TaMYB-7D activates the TaGAPDH5 promoter. Under drought stress, TaGAPDH5 overexpressing Arabidopsis thaliana lines displayed less intense DAB and NBT staining, higher soluble sugar contents, reduced wilting, and fewer dead leaves than wild type plants.

CONCLUSIONS

Collectively, this study characterized GAPDH gene family members in wheat species of different ploidy levels and identified TaGAPDH5 as a potential drought tolerance candidate, providing a basis for further functional validation and possible application in drought tolerance breeding.