Altered Target Sites as a Mechanism of Herbicide Resistance

Abstract

Development of herbicide-resistant crops has been generated, utilized either conventional and, mutation breeding or genetic engineering approaches, to be resistant to herbicides. Herbicide resistance and be due to target site-based or non-target site-based mechanism. To date, most of the reported herbicide resistance in plants has been linked to target site modification. Mechanisms of target site-based herbicide resistance of the amino acid synthesis inhibitors are reviewed in this paper, with emphasis on the biochemical and molecular basis as acetolactate synthase (ALS) and glutamine synthetase (GS) gene mutation. It is possible that the herbicide-resistant crops show a point mutation as base-pair substitution in the partial of ALS and GS gene. The substitution results in a modified amino acid sequence in the ALS and GS protein as target site-based resistance, and making it less sensitive to inhibitory effect of herbicide. This suggests that the mechanisms of target site-based herbicide resistance may be occurred after the translation or post translation in the ALS and GS gene. Altered target-site mutation in the ALS and GS gene may confer mechanism resistance to amino acid synthesis inhibitors, so that it is technically possible to develop the herbicide resistance trait in many crops.