Integrative Theory of the Mode of Action of Quinclorac: Literature Review1

Abstract

-Quinclorac is a systemic herbicide absorbed by germinating seeds, roots and leaves of seedlings. It is a selective compound for crops such as rice, canola, barley, corn, sorghum, and pasture. Quinclorac can be used to control various monocots and dicotyledonous weed species. The biochemical function of this herbicide in the plant has intrigued scientists for nearly four decades. The objectives of this review are to present evidence of three hypotheses on the biochemical functioning of quinclorac and to propose an integrative mode of action. The first theory on the mode of action of quinclorac is supported by evidence of inhibition of incorporation of C 14 -glucose into cellulose and hemicellulose, thus, affecting the cell wall synthesis. The second hypothesis suggests that quinclorac acts as an auxin in broadleaved weed species. In grass species, however, this herbicide appears to stimulate the activity of the 1-aminocyclopropane-1-carboxylate synthase enzyme and, subsequently, to increase the ethylene production; also, it seems to increase the cyanide acid content to phytotoxic levels. A third hypothesis to explain the harmful effect in some plant species is the formation of reactive oxygen species (ROS). Apparently, these processes are not mutually exclusive; therefore, an integrative theory for the action of quinclorac is suggested. It is theorized that the aforementioned biochemical activities are interconnected and can be the phytotoxic backbone to explain the herbicidal effect depending on the plant species and the plant growth stage, among other factors.Keywords: cellulose biosynthesis-inhibitor, cyanide, auxinic herbicide, reactive oxygen species. Palavras-chave: inibidor da síntese de celulose, herbicida auxínico, cianeto, espécies reativas de oxigênio. RESUMO

Differences in the Mode of Action of Florpyrauxifen-Benzyl between Barnyardgrass and Yerbadetajo

“…ABA can lead to stomatal closure and interfere with p tosynthesis, causing excessive accumulation of ROS, which also have toxic effects plants [37,62]. Previous studies have shown that ethylene accumulation mainly occurs monocotyledons, and ABA accumulation mainly occurs in dicotyledons after auxin a log treatment [63]. However, our previous studies confirmed that the accumulation ethylene and ABA could occur in monocotyledons (barnyardgrass) after quinclorac tre ment [38,45].…”

Confirmation and differential metabolism associated with quinclorac resistance in smooth crabgrass (Digitaria ischaemum)

“…The target process of auxin-mimicking herbicides in some dicot species entails the induction of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase in ethylene biosynthesis (Grossmann 2000a; Hansen and Grossmann 2000; Wei et al 2000). The ACC is enzymatically converted by 1-aminocyclopropane-1-carboxilic acid oxidase (ACO), leading to the production of ethylene, CO 2 , and cyanide (Fipke and Vidal 2016). Cyanide is produced in stoichiometrically equal amounts to ethylene in its biosynthetic pathway (Peiser et al 1984).…”

“…Studies of quinclorac-susceptible grass species have suggested that they are unable to quickly degrade cyanide, resulting in phytotoxic effects from cyanide accumulation in the shoot tissues (Abdallah et al 2006; Grossmann 2010; Grossmann and Kwiatkowski 2000). However, in quinclorac-resistant grass biotypes, ACC synthase activities are not induced, and there are no significant changes in the cyanide levels (Grossmann and Kwiatkowski 2000), suggesting that enzymatic insensitivity to quinclorac contributes to plant resistance (Fipke and Vidal 2016). An alternative resistance mechanism is possibly related to enhanced herbicide detoxification (Kreuz et al 1996).…”

Initial effects of quinclorac on the survival and growth of high biomass tree species

“…Norsworthy et al (2007) stated that 50 percent of Arkansas rice consultants preferred using herbicides propanil and quinclorac as a post-emergent herbicide for grassy and broadleaf weeds in rice fields and 32 percent of rice consultants recommended three or more applications in a growing season. Quinclorac is a selective auxin herbicide often used over rice, canola, barley, sorghum and pasture fields for the control of dicot weeds and some grass weeds with susceptible plants (Fipke & Vidal 2016). After the herbicide is sprayed, absorption occurs both through the leaves and through the roots with acropetal translocation through the plant (Williams et al 2004).…”