Early Changes in the Nucleotide Pools of Germinating Rust Uredospores

Abstract

Puccinia graminis uredospores were induced to germinate on a water surface and the nucleotide/nucleoside pools were determined by high performance liquid chromatography. Distinct phases of germination could be discriminated by correlating the changes of individual nucleotide pools with characteristic morphological changes. During the first 15 min no visible changes of the cell wall were observed whereas the adenine nucleotide pools increased strongly indicating an activation of the energy metabolism. The stage preceding hyphal growth revealed large increases in the precursor pool for cell wall synthesis (UDP‐N‐acetylglucosamine). The early phases of germination are obviously controlled by distinct metabolic transitions. Furthermore, correlations of pool contents and changes during germination with the germination efficiency of the three uredospore batches investigated are discussed.