Inorganic polyphosphates in the wheat stem rust fungus and in rust-infected wheat leaves

Abstract

Results presented in this paper establish the presence of inorganic polyphosphates in saprophytic cultures of the wheat stem rust fungus ( Puccinia graminis tritici), and in non-infected and rust- infected primary leaves of wheat. Evidence for the presence of these compounds was based on acid-lability, non-adsorption to charcoal, metachromatic reaction with toluidine blue, paper chromatographic mobility and histochemical staining. Ten days after inoculation, rust-infected primary leaves of wheat contained eight times more inorganic polyphosphate than control leaves of the same age. Much of this polyphosphate was located in the stem rust uredospores. Further analysis of the uredospores revealed that approximately 90% of the cold acid-soluble phosphorus which was not adsorbed to charcoal was in the form of inorganic polyphosphate. The corresponding figure for the saprophytic rust mycelium was 80%. Rust-infected wheat leaves and saprophytic mycelium contained both high and low molecular weight polyphosphates. The low molecular weight polyphosphates were heterogeneous with respect to electrophoretic mobility on polyacrylamide gels. In contrast, the polyphosphates of non-infected wheat leaves were of low molecular weight only and were relatively homogeneous.