EFFECT OF FENPICLONIL ON PHOSPHORYLATION OF GLUCOSE IN FUSARIUM-SULPHUREUM

The phenylpyrrole fungicide fenpiclonil inhibited the metabolism of gl ucose in mycelium of Fusarium sulphureum Schlecht at a concentration w hich only slightly inhibited mycelial growth (EC(15)). At the same con centration, fenpiclonil also inhibited accumulation and, to a greater extent, phosphorylation of 2-deoxy[U-C-14]glucose in starved mycelium loaded with unlabelled 2-deoxyglucose. Fenpiclonil did not affect cell -free phosphorylation of 2-deoxyglucose or the ATP content of mycelium . Therefore, the primary mode of action of the fungicide may be based on inhibition of transport-associated phosphorylation of glucose. This may cause a cascade of metabolic events which eventually lead to fung al growth inhibition and death. One major event affected by inhibition of transport-associated phosphorylation is the accumulation of polyol s, such as glycerol and mannitol, in mycelium. This was not observed i n an osmotically sensitive, fenpiclonil-resistant laboratory isolate o f the fungus.