Review—mechanism of action of herbicidal and fungicidal compounds on cell membranes

Abstract

The eukaryotic cell membrane is thought to consist of a mobile bilayer of phospholipid, sometimes intercalated with sterols, in which peripheral and transmembrane proteins are embedded. 7his provides a model whereby the mode of action of many fungicidal and herbicidal compounds can be rationalised and understood. Some compounds, such as the polyene antibiotics, steroidal saponins and certain phytoalexins, induce membrane malfunction by direct insertion, often complexing with vital components. Others, such as paraquat and the nitrodiphenyl ether herbicides, cause membrane damage by inducing lipid peroxidations. Furthermore, there are many compounds, including the sterol-biosynthesis-inhibiting fungicides and the aryloxyphenoxypropionate and cyclohexanedione herbicides, which interfere with the biosynthesis of membrane components. Because membrane structure is jiindamentally similar in eukaryotes, it is important to discover the reasons for any differential toxicity displayed by these compounds and, if necessary, to find ways of optimising desirable patterns of selectivity.Pestic. Sci. 0031-613X/90/$03.60 0 1990 SCI. Printed in Great Britain

<I>Acromyrmex octospinosus</I> (Hymenoptera: Formicidae) Management: Effects of TRAMILs Fungicidal Plant Extracts

“…3). Many studies suggest that the alkaloid tomatine is responsible for the antifungal activity (Wilson et al 1961, Lydon and Duke 1989, Burden et al 1990). The absence of a fungicidal effect of L. esculentum fruit extract, despite its well-known antifungal compound, is not surprising in that the glycoalkaloid content depends on the plant part.…”

Detection and Significance of Symptomless Latent Infections of Monilinia Fructicola in Plums

“…The herbicidal activity of paraquat has been shown to be a light-mediated generation of free radicals which induce lipid peroxidation and loss of membrane integrity (Burden et al 1990, Dodge 1971. The toxic reaction may be complete within a few hours of illumination (Dodge 1971), but in the honey mesquite, mesophyll cells were damaged by paraquat as much in the dark as in the light (Baur et al 1969).…”

Isolation and characterization of polyene-resistant mutants from the maize smut pathogen, Ustilago maydis, defective in ergosterol biosynthesis

“…al., 1986;Dahl et al, 1987). The essential requirement for ergosterol in cellular and metabolic processes is demonstrated clearly by the effectiveness of EBIs in preventing fungal growth (Burden et al, 1990;Girling, 1991). However, the relative contributions of the 'bulk' membrane function and the 'sparking' role to the functioning of fungal cells remains unclear.…”

“…EBIs have proved extremely useful as tools for investigating the effect of abnormal sterol accumulation and ergosterol depletion on growth and membrane function (Burden et al, 1989). However, mutants blocked at specific points along the ergosterol biosynthetic pathway would offer a unique opportunity to study both the role of ergosterol and the mode of action of EBIs in a more precise and detailed manner.…”