Herbicides targets

LANGE, B.M., KETCHUM, R.E.B., CROTEAU, R., Isoprenoid biosynthesis metabolite profiling of peppermint oil gland secretory cells and application to herbicide target analysis, Plant Physiol., 2001,127, 305-314. 

Animals acquire many of their nutrients in a ready made form from the food that they eat. Plants, however, have to biosynthesise everything that they need for efficient growth. The first section of this chapter discussed photosynthesis, a fundamental biosynthetic process, but plants also synthesise other components that animals do not. These biosynthetic processes are good examples of potentially plant selective herbicidal targets. Amino acids are the building blocks of proteins and as such their biosynthesis is one such process. 

Matthews, J.M., J.A.M. Holtum, D.R. Liljegren, B. Furness, and S.B. Powles (1990). Cross-resistance to herbicides in annual ryegrass (Lolium rigidum). 1. Properties of the herbicide target enzymes acetyl-coenzyme A carboxylase and acetolactate synthase. Plant... 

I) The most obvious is the direct use of the allelochemicals as new herbicides, targeting new sites of action. Few successful examples can be mentioned but, among them, glyphosate (1) [the synthetic version of phosphinothricin... 

The need exists to expand the repertoire of tools available for weed management systems. What little we know of the molecular target sites of natural phytotoxins indicates that they are inhibitors of a broad array of enzymes and other molecular targets that have not been the focus of herbicide discovery efforts [1]. At present, commercially available herbicides target a relatively limited number of enzymes and metabolic pathways. The discovery of new target sites is a growing emphasis of pesticide companies, especially since the U.S. Food Quality Protection Act has combined food tolerance levels of pesticides with the same molecular target sites. 

REDUCTION IN THE SENSITIVITY OF HERBICIDE TARGET SITES. Crossresistance may involve changes in the sensitivity of herbicide target sites. However, if this is the only mechanism for resistance in Lolium there must be changes in more than one target site since there is resistance to more than one herbicide class. 

This indicates that some de novo FA biosynthesis occurs in the apicoplast. It may occur in a discrete compartment or be related to a specific but crucial type of lipid (predominantly C-10 to C-14, as shown by Surolia and Surolia, 2001). This pathway is probably quantitatively minor but appears to be critical to parasite survival. It could be involved in the synthesis of lipids required by the apicoplast or a specific lipid that may be provided to the parasite. A major interest resides in the fact that FAS II is structurally and functionally distinct from the equivalent pathway in the vertebrate host, and would explain the susceptibility of the malarial parasite to herbicides targeting the enzyme. It is considered today as a validated target that still needs to be developed into a practical antimalarial. 

Many commercial herbicides inhibit photosynthesis by displacing Qg from its binding site in D1 and thus block electron transport from to They belong to various chemical classes like triazines, ureas or phenols (For a review see ref. 29) and pollute soil and water due to their massive use in agriculture. This in turn can be harmful for human and animal health and necessitates the development of fast and sensitive detection methods. Coincidentally, the herbicidal target itself is part of the PSII complex, which represents a reporter system directly coupled to an analyte binding site. Thus the most obvious application of the Dl protein in association with other central PSII proteins is its use as a biosensor for herbicides. 

T. A. Walsh (Dow AgroSciences, USA) introduced the concept of chemical genetics and described a successful example of identifying several novel herbicide targets using this strategy. 

Cole, D. J., Rodgers, M. W. Plant Molecular Biology for Herbicide-Tolerant Crops and Discovery of New Herbicide Targets in Herbicides and Their Mechanisms of Action, Cobb, A., Kirkwood, R. C. (Eds.), ShefSeld Academic Press, Sheffield, UK, 2000, 239-278. 

Hydroxfpherp/lpy/ruvate Dioxygenase (HPPD) - the Herbicide Target 213... 

Safener Interactions with the Herbicide Target Site... 

In general, herbicide resistance can be achieved through four primary strategies detoxification of the herbicide to a non-phytotoxic metabolite expression of an herbicide insensitive target overexpression of the herbicide target and cellular sequestration of the herbicide away from the target. Of these, only the first two strategies have been successfully used to develop commercial products to date. Readers are referred to other reviews on herbicide resistance [3, 4]. 

To date, all attempts to synthesize more potent structural analogues of glutamate with herbiddal adivity failed despite the research efforts dedicated to the herbicide target glutamine synthetase [19]. 

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