Alterations in nucleotide and pyrophosphate levels in Phytophthora plamivora following exposure to the antifungal agent potassium phosphonate (phosphite)

Abstract

Short exposure (up to 3 h) of phosphate-starved mycelium from Phytophthora palmivora to the antifungal agent potassium phosphonate resulted in decreased levels of NAD, ATP, and a number of compounds tentatively identified as polyphosphorylated nucleotides (alarmones). ADP, AMP and adenosine levels were not increased, as would be expected if phosphorylation were the site of inhibition. Pyrophosphate levels, however, were raised. The incorporation of [32P]phosphate into phospholipids and other macromolecules was not affected during this short exposure. Together, these results suggest that adenylate synthesis may be a primary site of action of phosphonate in the fungus.