Identification of the Glyceraldehyde-3-Phosphate Dehydrogenase (GeGAPDH) Gene Family in Gastrodia elata Revealing Its Response Characteristics to Low-Temperature and Pathogen Stress

The glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene plays a pivotal role in the glycolysis/gluconeogenesis process, contributing significantly to glycosyl donor synthesis, plant growth and development, and stress responses.Gastrodia elataBl., a heterotrophic plant in the Orchidaceae family, has its dried tubers used as the traditional Chinese medicine. This study identified threeGeGAPDHgenes inG. elata, all encoding basic, stable, hydrophilic proteins. Phylogenetic analysis and subcellular localization predictions categorizedGeGAPDH1as a plastid subtype, whileGeGAPDH2andGeGAPDH3were classified as cytoplasmic subtypes. Prokaryotic expression experiments demonstrated successful expression of the GeGAPDH1 protein inEscherichia coli, which exhibited significant GAPDH enzymatic activity. Subcellular localization experiments showed that GeGAPDH1 was localized in the plastid. Expression analysis indicated that the threeGeGAPDHgenes were predominantly expressed in tubers. Under low-temperature stress, although the total GAPDH enzyme activity in tubers did not change significantly, the expression ofGeGAPDH1was significantly up-regulated, whileGeGAPDH2andGeGAPDH3were significantly down-regulated. This suggests that different subtypes ofGeGAPDHmay regulate cold resistance through different pathways. Upon pathogen infection, theGeGAPDHgene family exhibited pathogen-specific regulatory patterns. During infection byFusarium oxysporum, both the expression levels of all threeGeGAPDHgenes and the total GAPDH enzyme activity in tubers increased significantly; however,F. solaniinfection induced a significant increase in total GAPDH enzyme activity without significant changes in gene expression. These results suggest that theGeGAPDHgene family may respond to different pathogen infections through transcriptional or translational regulation mechanisms. This study systematically identified and characterized theGeGAPDHgene family inG. elata, providing a theoretical foundation for understanding the functional differentiation ofGAPDHin heterotrophic plants.