Strobilurins

About: Strobilurins is a research topic. Over the lifetime, 197 publications have been published within this topic receiving 5296 citations.

The strobilurin fungicides.

Abstract: Strobilurins are one of the most important classes of agricultural fungicide. Their invention was inspired by a group of fungicidally active natural products. The outstanding benefits they deliver are currently being utilised in a wide range of crops throughout the world. First launched in 1996, the strobilurins now include the world's biggest selling fungicide, azoxystrobin. By 2002 there will be six strobilurin active ingredients commercially available for agricultural use. This review describes in detail the properties of these active ingredients--their synthesis, biochemical mode of action, biokinetics, fungicidal activity, yield and quality benefits, resistance risk and human and environmental safety. It also describes the clear technical differences that exist between these active ingredients, particularly in the areas of fungicidal activity and biokinetics.

Review of strobilurin fungicide chemicals

Abstract: Strobilurins are natural products isolated and identified from specific fungi. Natural strobilurins were named in the order of their discovery as strobilurin-A followed by strobilurin-B, C, D etc. Their discovery opened the door for new chemistry of synthetic fungicides. Applying Quantitative Structural Activity Relationship (QSAR) on the structures of the natural strobilurins, many pesticide companies were able to discover many synthetic analogues that are more efficacious and more stable fungicides. At present there are about eight synthetic strobilurins in the fungicides worldwide market. Some of these products are worldwide registered for use as agrochemical and some are in the process of registration. This class of fungicides is relatively new, as crop protection products and information about them is still fairly scarce. In this review, syntheses and chemistry of natural and synthetic strobilurins are discussed. Also, the mode of action, efficacy, biotic/abiotic degradation, analytical methods, and agricultural uses are discussed.

The strobilurins--new antifungal antibiotics from the basidiomycete Strobilurus tenacellus.

Abstract: The strobilurins are two antifungal antibiotics which were isolated from the mycelium of Strobilurus tenacellus strain No. 21602. The strobilurins A and B are highly active against yeasts and filamentous fungi. In vitro antitumor activity was tested using cells of the asciticform of EHRLICH carcinoma. The strobilurins strongly inhibited the incorporation of radioactive leucine, uridine, and thymidine into the acid-insoluble fraction of cells (protein, RNA, and DNA). The molecular formulas as determined by high resolution mass spectrometry are C16H18O3 for strobilurin A and C17H19ClO4 for strobilurin B.

Chemical Control of Botrytis and its Resistance to Chemical Fungicides

Abstract: The chemical control of Botrytis spp., and especially B. cinerea the causal agent of grey mould on many crops, can be achieved by several families of fungicides. Among those affecting fungal respiration, the oldest ones are multi-site toxicants (e.g. dichlofluanid, thiram); newer ones are uncouplers (e.g. fluazinam), inhibitors of mitochondrial complex II (e.g. boscalid) or complex III (e.g. strobilurins). Within anti-microtubule botryticides, negative-cross resistance can occur between benzimidazoles (e.g. carbendazim) and phenylcarbamates (e.g. diethofencarb), a phenomenon determined by a mutation in the gene encoding E-tubulin. Aromatic hydrocarbon fungicides (e.g. dicloran), dicarboximides (e.g. iprodione, procymidone, vinclozolin) and phenylpyrroles (e.g. fludioxonil) affect the fungal content of polyols and resistance to these various compounds can be associated with mutations in a protein histidine kinase, probably involved in osmoregulation. However, dicarboximide-resistant field strains of B. cinerea are sensitive to phenylpyrroles. Anilinopyrimidines (e.g. cyprodinil, mepanipyrim, pyrimethanil) inhibit methionine biosynthesis but their primary target site remains unknown. In few situations, resistance of commercial significance has been recorded. Among sterol biosynthesis inhibitors those inhibiting 14D - demethylase (DMIs) which are widely used against many fungal diseases are of limited interest against Botrytis spp., whereas the hydroxyanilide fenhexamid, which inhibits the 3-keto reductase involved in sterol C4-demethylations, is a powerful botryticide. Monitoring conducted in French vineyards revealed the presence of multi-drug resistant (MDR) strains, a phenomenon probably determined by over- production of ATP-binding cassette transporters. Resistance towards fungicides of the different groups is described throughout the chapter.

A critical evaluation of the role of alternative oxidase in the performance of strobilurin and related fungicides acting at the Qo site of Complex III

Abstract: Mitochondrial respiration conserves energy by linking NADH oxidation and electron-coupled proton translocation with ATP synthesis, through a core pathway involving three large protein complexes. Strobilurin fungicides block electron flow through one of these complexes (III), and disrupt energy supply. Despite an essential need for ATP throughout fungal disease development, strobilurins are largely preventative; indeed some diseases are not controlled at all, and several pathogens have quickly developed resistance. Target-site variation is not the only cause of these performance difficulties. Alternative oxidase (AOX) is a strobilurin-insensitive terminal oxidase that allows electrons from ubiquinol to bypass Complex III. Its synthesis is constitutive in some fungi but in many others is induced by inhibition of the main pathway. AOX provides a strobilurin-insensitive pathway for oxidation of NADH. Protons are pumped as electrons flow through Complex I, but energy conservation is less efficient than for the full respiratory chain. Salicylhydroxamic acid (SHAM) is a characteristic inhibitor of AOX, and several studies have explored the potentiation of strobilurin activity by SHAM. We present a kinetic-based model which relates changes in the extent of potentiation during different phases of disease development to a changing importance of energy efficiency. The model provides a framework for understanding the varying efficacy of strobilurin fungicides. In many cases, AOX can limit strobilurin effectiveness once an infection is established, but is unable to interfere significantly with strobilurin action during germination. A less stringent demand for energy efficiency during early disease development could lead to insensitivity towards this class of fungicides. This is discussed in relation to Botrytis cinerea, which is often poorly controlled by strobilurins. Mutations with a similar effect may explain evidence implicating AOX in resistance development in normally well-controlled plant pathogens, such as Venturia inaequalis.