Overexpression of PtPEPCK1 gene promotes nitrogen metabolism in poplar

Abstract

To understand the function of phosphoenolpyruvate carboxylase kinase, we introduced PtPEPCK1 gene under the control of 35S promoter into 84K poplar (Populus alba × P. glandulosa). PtPEPCK1 gene is well-known for its role in gluconeogenesis. However, our data confirmed that it has significant effects on amino acid biosynthesis and nitrogen metabolism. Immunohistochemistry and fluorescence microscopy indicate that PtPEPCK1 is specifically expressed in the cytoplasm of the spongy and palisade tissues. Overexpression of PtPEPCK1 was characterized through transcriptomics and metabolomics. The metabolites concentration of the ornithine cycle and its precursors also increased, of which N-acetylornithine was up-regulated almost 50-fold and ornithine 33.7-fold. These were accompanied by a massive increase in levels of several amino acids. Therefore, overexpression of PtPEPCK1 increases amino acid levels with urea cycle disorder.