Accumulation of systemic fungicides and other solutes by haustorial complexes isolated from Pisum sativum infected with Erysiphe pisi

Haustorial complexes, isolated from pea leaves infected with powdery mildew, were incubated with individual C‐labelled systemic fungicides or other solutes, and the accumulation of these compounds by the complexes was assessed following filter centrifugation of the products through silicone oil. Inulincarboxylic acid and butyric acid were not absorbed; glucose, sucrose, acetic acid and glycerol were absorbed very slowly by the complexes. All the systemic fungicides, which included nuarimol, fenarimol, dimethirimol, ethirimol, and other pyrimidine‐based analogues, were accumulated against large concentration gradients (30‐1500 fold). The fatty acids, linoleic and lauric, were also readily accumulated. The accumulation of the fatty acids and fungicides was usually complete within 5–15 min. The degree of accumulation of all the solutes was significantly correlated with their lipophilicity, indicating that partitioning of compounds into sub‐cellular lipids was the major mechanism determining accumulation by the complexes. The cations 2‐hydroxyethylarnmonium and 1‐methylpyridinium were also accumulated against large concentration gradients (18‐and 46‐fold, respectively) but less rapidly than the fungicides. The significance of these findings for the systemic distribution and mode of action of fungicides is discussed