Altered expression of pyrophosphate: Fructose-6-phosphate 1-phosphotransferase affects the growth of transgenic Arabidopsis plants

Pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) catalyzes the reversible interconversion of fructose-6-phosphate and fructose-1,6-bisphosphate, a key step in the regulation of the metabolic flux toward glycolysis or gluconeogenesis. To examine the role of PFP in plant growth, we have generated transgenic Arabidopsis plants that either overexpress or repress Arabidopsis PFP sub-unit genes. The overexpressing lines displayed increased PFP activity and slightly faster growth relative to wild type plants, although their photosynthetic activities and the levels of metabolites appeared not to have significantly changed. In contrast, the RNAi lines showed significantly retarded growth in parallel with the reduced PFP activity. Analysis of photosynthetic activity revealed that the growth retardation phenotype of the RNAi lines was accompanied by the reduced rates of CO₂ assimilation. Microarray analysis of our transgenic plants further revealed that the altered expression of AtPFPβ affects the expression of several genes involved in diverse physiological processes. Our current data thus suggest that PFP is important in carbohydrate metabolism and other cellular processes.