Catalyzes the irreversible hydrolysis of pyrophosphate (PPi) to phosphate. The MgPPi(2-) complex binds to the enzyme only after a free Mg(2+) ion has bound (Ref.9). No activity with glycerol-3-phosphate, glucose-6-phosphate, p-nitrophenylphosphate, ADP, NADP(+), NAD(+),NADH, NADPH or phosphoribosyl pyrophosphate as substrates (Ref.9). Controls the equilibrium of gluconeogenic reactions in the heterotrophic growth phase of early seedling establishment. Determinates the rate of cytosolic glycolysis, providing carbon for seed storage lipid accumulation (PubMed:22566496). diphosphate + H2O = H(+) + 2 phosphate Inhibited by Zn(2+), Ca(2+), Ba(2+), Fe(2+), Co(2+), Cu(2+), Eu(2+), Eu(3+) and Mn(2+). kcat is 9.28 sec(-1) for pyrophosphate. Monomer. Ubiquitous. Lower level of expression in ovary, stigma and pollen. Expressed throughout plant development, with a slight reduction during senescence. Belongs to the PPase family.