Polyamine Concentrations and Activities of Ornithine and Arginine Decarboxylase in Wheat Infected with the Stem Rust Fungus

Abstract

Summary Inoculation of the first leaves of wheat ( Triticum aestivum L.) with the black stem rust fungus, Puccinia graminis f.sp. tritici Erikss & E. Henn., resulted in substantial increases in polyamine concentrations. Thus, several-fold increases in the concentrations of putrescine, spermidine and spermine were detected in rusted leaves. The activity of arginine decarboxylase in rusted leaves was small and rust infection caused a reduction in activity. Ornithine decarboxylase activity (both cytosolic and bound) was not detectable in healthy first leaves, but small increases in activities of both forms of ODC were detected in rust-infected leaves. Most of the increased polyamine concentration observed in whole leaves was localized in fungal pustules, although polyamine levels were also increased in regions between pustules. Similarly, activities of cytosolic and bound ODC were highest in pustule regions, with much lower activities in regions between pustules. It is likely that increased ODC activity in pustule areas represents fungal ODC.