Multiple Forms of Orthophosphoric Monoester Posphohydrolase in Phosphate Starved Wolffia arrhiza

Abstract

Phosphatase forms from axenic batch cultures of Wolffia arrhiza, strain WJ, were investigated under normal (P +) or phosphorus deficient (P −) conditions. Electrophoretic separation of orthophosphoric monoester phosphohydrolase on polyacrylamide-gel showed marked changes in the band pattern after phosphate starvation. Tree low rp multiple forms (α-bands) resistant to heat (10 min. 80°C) are typical for (P −) plants. The α2-enzyme could not be detected in (P +) plants, while the α1- and α3-enzymes were faintly coloured in gels of concentrated (P +) extracts. Most of the phosphatase activity of (P +) plants was found to have high rp-values (γ-bands), these enzyme forms were completely inactivated by heat treatment (10 min, 75°C). While the γ1 and γ2-bands are present in (P +) as well as n (P −) plants, the γ3-enzyme could only be detected in (P −) plants. The highest heat stability of all the phosphatase forms was shown by the enzyme β2, which occurred in (P −), but not in (P +) plants. In concentrated media of (P −) plants, α-enzyme forms as well as the β2-enzyme could be detected, whereas no γ-enzyme forms were found. In (P +) plants no evidence of the release of phosphohydrolases is provided.