Glycerol-3-phosphate dehydrogenase (GPDH) gene family in Zea mays L.: Identification, subcellular localization, and transcriptional responses to abiotic stresses

Glycerol-3-phosphate dehydrogenase (GPDH) catalyzes the formation of glycerol-3-phosphate, and plays an essential role in glycerolipid metabolism and in response to various stresses in different species. In this study, six ZmGPDH genes were obtained by a thorough search against maize genome, and designated as ZmGPDH1-6, respectively. The structural and evolutionary analyses showed that the ZmGPDHs family had typical conserved domains and similar protein structures as the known GPDHs from other plant species. ZmGPDHs were divided into NAD(+)-dependent type A form (ZmGPDH1-5) and FAD-dependent type B form (ZmGPDH6) based on their N-terminal sequences. Four full length ZmGPDHs were fused with GFP fusion proteins, and their subcellular localization was determined. ZmGPDH1 and ZmGPDH3 were located to the cytosol and mainly recruited to the surface of endoplasmic reticulum (ER), whereas ZmGPDH4 and ZmGPDH5 were located in the chloroplast. The transcriptional analysis of the ZmGPDHs in different maize tissues revealed relatively high level of transcripts accumulation of ZmGPDHs in roots and early stage developing seeds. Furthermore, we examined the transcriptional responses of the six GPDH genes in maize under various abiotic stresses, including salt, drought, alkali and cold, and significant induction of ZmGPDHs under osmotic stresses was observed. Together, this work will provide useful information for deciphering the roles of GPDHs in plant development and abiotic stress responses.