Overexpression of Pyrophosphate-Dependent Phosphofructokinase (PFP) in Transgenic Tobacco

Abstract

PPi- dependent phosphofructokinase (PFP) catalyzes a reversible cytosolic interconversion of fructose-6-phosphate and fructose-1,6-bisphosphate. This reaction is also catalyzed in the glycolytic direction by ATP-dependent phosphofructokinase (PFK) and in the gluconeogenic direction by fructose-1,6- bisphosphatase (FBPase). The role of PFP in plants is not clear but many functions have been proposed: a role in glycolysis, a role in gluconeogenesis, regulation of PPi content in the cytosol, equilibration of hexose-P and triose-P pools and a role in adaptation to stress (eg. low Pi, low temp., anaerobiosis) (1). To elucidate the role of PFP in plants previous studies examined transgenic tobacco (2) and transgenic potato (1) with strongly reduced expression of PFP. However, no adverse effects of this reduction were found on plant growth and metabolism under both control and stress (low Pi, low N, low temp., anaerobiosis) conditions. To gain further insight into the role of PFP, the present study examined the effect of overexpression of unregulated PFP on plant metabolism in tobacco.