Acifluorfen-methyl effects on porphyrin synthesis in Lemna pausicostata Hegelm. 6746

Effect of Diphenyl Ether Herbicides on Oxidation of Protoporphyrinogen to Protoporphyrin in Organellar and Plasma Membrane Enriched Fractions of Barley

“…'The study was Several laboratories have found the photobleaching DPE2 herbicides to increase greatly the intracellular levels of the photodynamic tetrapyrrole, protoporphyrin, causing light dependent phytotoxic effects (2-4, 6, 14-16, 18, 22-24, 26, 29). DPE herbicides also inhibit Protox, which is the last enzyme of the common branch of the heme and Chl biosynthetic pathways in plants and oxidizes protoporphyrinogen to protoporphyrin (1,5,12,20,21,27,30 (2,19). In addition, these findings are compatible with previous in vivo localization studies in intact plant cells showing that DPE treated plant cells exhibit a rapid accumulation of porphyrins at nonplastidic sites, such as the plasma membrane or in the cytoplasm (16).…”

Cellular Localization of Protoporphyrinogen-Oxidizing Activities of Etiolated Barley (Hordeum vulgare L.) Leaves (Relationship to Mechanism of Action of Protoporphyrinogen Oxidase-Inhibiting Herbicides)

“…Paradoxically, inhibition of this enzyme causes the accumulation of abnormally high levels of Proto IX, the product of Protox (Beceml and Duke, 1989;Sherman et al, 1991a). Accumulation is rapid, being easily detectable within 15 to 30 min of exposure of tissues or whole plants to the herbicide (Beceml and Duke, 1989;Matsumoto and Duke, 1990). Proto IX is a photodynamic pigment that, in the light, causes rapid membrane peroxidation and cellular death.…”

Accumulation of Protoporphyrinogen IX prior to Protoporphyrin IX in Intact Plants Treated with Protoporphyrinogen IX Oxidase-Inhibiting Herbicides

“…Leaf discs excised from cucumber cotyledons or slices of wheat and cleavers shoots were homogenized with 3 to 4 ml of HPLC-grade MeOH/0.1 M NH 4 OH (9/1, v/v; basic solvent) [11][12][13][14][15][16][17][18][19][20] with the handy micro homogenizer at full power for 15 sec. The homogenate was centrifuged at 3,000ϫg for 5 min at room temperature.…”

“…Therefore, we preliminary determined the concentration of Mg-Proto IX extracted with MeOH/0.1 M NH 4 OH (9/1, v/v). [11][12][13][14][15][16] The MgProto IX concentration was less than 0.1 nmol/g fresh weight (data not shown) and thus negligible in the calculation of Proto IX concentration in plants. Therefore, the Protogen concentration was calculated by subtracting the Proto IX concentration in the acidic solvent from that in the basic solvent (including auto-oxidized Protogen).…”

“…[11][12][13][14][15][16][17][18][19][20] However, the auto-oxidation of Protogen to Proto IX is not well understood, because Protogen is completely auto-oxidized to Proto IX in basic solutions via evaporation. Therefore, Fig.…”