Nucleic Acid and Protein Synthesis
The syntheses of nucleic acids and proteins in plants have, with two exceptions, not been proven to be primary targets for the action of herbicides. However, since the syntheses of nucleic acids (RNA, DNA) and proteins depend on a continuous supply of metabolic energy in the form of ATP, they might be inhibited secondarily. In effect, when studying the available data on the influence of herbicides on RNA and protein synthesis in the dark (Table 32), the most inhibitory compounds are found to be dinoseb, ioxynil, and pyrichlor, and these are well-known uncouplers of oxidative phosphorylation. Other compounds like e.g. CDAA, chlorpropham, endothal, propachlor, and 2,4,5-T may inhibit the syntheses of these polymers as a consequence of another primary metabolic interference (e.g. for CDAA and propachlor ). However, at the high concentrations employed in some of these experiments, partial uncoupling may also be induced by many herbicides (p. 116) which exhibit a different mode of action at lower concentrations in other systems (e.g. CIPC, diuron, EPTC, propachlor, prop anil, 2,4,5-T, trifluralin). Similarly, photosynthesis-inhibiting herbicides also indirectly inhibit other metabolic processes, in this case in the light (e.g. atrazine, bromacil, monuron). To sum up, the inhibition by herbicides of in vivo systems synthesizing proteins or nucleic acids may usually be regarded as a secondary process.
KeywordsNucleic Acid Protein Synthesis Ribosomal Subunit Secondary Process Inhibitory Compound
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