Soybean Mitochondrial Response to Prometryne and Fluometuron

Abstract

Experiments were conducted to determine the effect of 3-(m-trifluoromethylphenyl)-1,1-dimethylurea (fluometuron) and 2,4-bis(isopropylamino)-6-methylmercapto-s-triazine (prometryne) on oxygen consumption by mitochondria isolated from the hypocotyls of soybean (Glycine max L., var. Lee) seedlings. Prometryne caused a decrease in second state 3 oxidation of both malate and succinate, but the decrease was overcome by 2,4-dinitrophenol (hereinafter referred to as DNP), indicating a response similar to that of oligomycin. Fluometuron caused an increase in second state 4 oxidation of both malate and succinate and overcame the inhibition of oxidative phosphorylation caused by oligomycin, indicating an uncoupling response similar to DNP. Fluometuron was also shown to reverse the inhibition of oxidative phosphorylation caused by prometryne. Concentrations of prometryne causing the 50% inhibitory response were somewhat higher than those reported for s-triazines on other tissues, while those for fluometuron were well within the inhibitory range reported for other substituted ureas.