The Herbicide Saflufenacil (Kixor™) is a New Inhibitor of Protoporphyrinogen IX Oxidase Activity

Abstract

Saflufenacil (Kixor™) is a new herbicide of the pyrimidinedione chemical class for preplant burndown and selective preemergence dicot weed control in multiple crops, including corn. In this study, the mode of action of saflufenacil was investigated. For initial characterization, a series of biotests was used in a physionomics approach for comprehensive physiological profiling of saflufenacil effects. With the use of treated duckweed plants, metabolite profiling was performed based on quantification of metabolite changes, relative to untreated controls. Physiological and metabolite profiling suggested a mode of action similar to inhibitors of protoporphyrinogen IX oxidase (PPO) in tetrapyrrole biosynthetic pathway. Saflufenacil inhibited PPO enzyme activity in vitro with 50% inhibition of 0.4 nM for the enzymes isolated from black nightshade, velvetleaf, and corn. PPO inhibition by saflufenacil caused accumulations of protoporphyrin IX (Proto) and hydrogen peroxide (H2O2) in leaf tissue of black nightshade and velvetleaf. In corn, only slight increases in Proto and H2O2 were found, which reflects in planta tolerance of this crop. The results show that saflufenacil is a new PPO-inhibiting, peroxidizing herbicide.

Herbicide selectivity in alfalfa crops

“…This herbicide belongs to the pyrimidinedione family and inhibits the enzyme protoporphyrinogen oxidase (PROTOX) (Grossman et al 2010). In plants treated with saflufenacil, phytotoxicity could be observed a few hours after application, and phytotoxicity symptoms increased when the dose administered also increased ( Figure 2C).…”

Action of rain on formulations of glyphosate mixed with saflufenacil for the control of Brachiaria decumbens

“…Such apparently contradictory results found in the literature indicate that, in addition to environmental conditions at the time of application, herbicide absorption efficacy may be greatly influenced by several factors such as different formulations, concentration of herbicides and surfactants, species and phenological stages of weed development, growth habits, leaf morphology and epicuticular wax composition (KIRKWOOD; MCKAY, 1994;CHACHALIS et al, 2001a;HUANGFU et al, 2007). It should be noted that a high amount of epicuticular wax may be characterized in some species as an effective barrier to the absorption of herbicides (CHACHALIS et al, 2001b).…”

“…It should be noted that a high amount of epicuticular wax may be characterized in some species as an effective barrier to the absorption of herbicides (CHACHALIS et al, 2001b). However, weeds with a high stomatal density in their leaves may present relatively high levels of herbicide uptake (HUANGFU et al, 2007).…”

“…Saflufenacil is an herbicide inhibitor of the proto-porphyrinogen IX oxidase enzyme (PPO or PROTOX) used during post-emergence for a broad control of eudothycotton weeds (GROSSMANN et al, 2010). It is noteworthy that, in a study conducted by EUBANK et al, (2013), the authors observed that the spray of saflufenacil mixed with glyphosate for the control of glyphosate-resistant Conyza canadensis provided an additive effect on the control of this species.…”

Interactions of Saflufenacil with Other Herbicides Promoters of Oxidative Stress to Control Joyweed1

“…Saflufenacil herbicide inhibits the enzyme protoporphyrinogen IX oxidase (Protox) (Grossmann et al, 2010) and has recently been registered in Brazil. While performing action through mechanisms of action that are different from saflufenacil, herbicides paraquat, metribuzin and clomazone are also promoters of oxidative stress in plants, leading to lipid peroxidation and irreversible damage to cell membranes (Hess, 2000).…”