Studies into the action of the diphenyl ether herbicides acifluorfen and oxyfluorfen. Part I: Activation by light and oxygen in leaf tissue

Abstract

The effect of acifluorfen and oxyfluorfen on chlorophyll bleaching, lipid peroxidation and photosynthesis in pea leaf discs was studied. Both her‐ bicides induced light‐dependent bleaching and lipid peroxidation, the level of damage being greater at higher light intensities. Photosynthetic carbon dioxide fixation was only partially inhibited in treated leaf discs incubated in darkness, thus indicating that these herbicides did not inhibit photo‐ synthesis as a primary mode of action. Leaf discs maintained in darkness showed no visible signs of injury, and light‐dependent herbicide‐induced damage was reduced by incubating discs under nitrogen, orpre‐incubating them with the electron‐transport inhibitor monuron. It is suggested that acifluorfen and oxyfluorfen are activated by a light‐dependent process, which requires photosynthetic electron transport.

Antioxidative defense activation in soybean cells

“…Peroxidizing herbicides like the diphenyl ether oxyfluorfen induce an endogenous formation of ROS, i.e., singlet oxygen and superoxide anions, by interrupting chlorophyll biosynthesis on the step of protoporphyrinogen IX oxidation ( Böger and Wakabayashi 1995). Peroxidative attack of cellular components by diphenyl ether herbicides has been shown to be strictly dependent on light and oxygen ( Orr and Hess 1981; Gilham and Dodge 1987). During oxidative stress induced by oxyfluorfen in soybean cells, adaptations of antioxidants and antioxidative enzymes have been measured ( Knörzer et al 1996).…”

The Regulatory Evaluation of the Skin Effects of Pesticides

“…There were four cases associated with use of oxadiazon in the handler database, including one episode of dermatitis following direct contact (case 1988-813, Oxyfluorfen Oxyfluorfen is used for preemergent and postemergence control of weeds on labeled crops, inhibiting the protoporphyrinogen oxidase step in photosynthesis (Gilham and Dodge, 1987 …”

Enhanced Phototherapy Activity by Employing a Nanosilica-Coumarin–Acifluorfen Conjugate as the Supplementary Light Source Generator

“…For instance, ACI at 1 μM strongly inhibited the growth of tomato cell cultures in 40 μmol m –2 s –1 white light but exhibited little inhibitory activity against cultures in darkness . Pea leaf discs treated with 10 μM of ACI in 350 μmol m –2 s –1 white light for 48 h showed great chlorophyll bleaching (about 50%) and loss of photosynthetic activity (about 40%), but incubation in darkness had no effect on the chlorophyll content of leaf discs …”

“…13 Pea leaf discs treated with 10 μM of ACI in 350 μmol m −2 s −1 white light for 48 h showed great chlorophyll bleaching (about 50%) and loss of photosynthetic activity (about 40%), but incubation in darkness had no effect on the chlorophyll content of leaf discs. 14 7-Hydroxycoumarin-4-acetic acid (HCA) is used extensively as a fluorescence labeling reagent that possesses a strong fluorescence band at emission from 400 to 500 nm upon excitation at about 350 nm. 15−17 (from 400 to 500 nm).…”