Chloroplast Engineering for Herbicide Resistance via Acetyl Co-A Carboxylase

Introduction

Acetyl-CoA carboxylase (ACCase) is an important enzyme for fatty acid biosynthesis in plant chloroplasts. Both forms of ACCase are present in bilobal plants, a prokaryotic form known as a heteromeric form and a eukaryotic form known as a homomeric form. Prokaryotic heteromers are herbicide resistant, while eukaryotic homomers are herbicide sensitive. ACCase is the target site of many highly successful herbicides. ACCase herbicides inhibit de novo synthesis of fatty acids in sensitive weeds, resulting in rapid plant necrosis and death. These compounds mainly include aryloxyphenoxypropionates (FOPs), cyclohexanediones (DIMs) and phenylpyrazolines (DENs). Currently widely and repeatedly used ACCase herbicides have selected for resistance in key weed species including 20 genera.

Fig. 1. Compartmentation of Two Forms of ACCase in Plants. (Sasaki Y, et al., 2004)

Solutions

Herbicides targeting ACCase are potent and selective grass herbicides. Our engineers have been working to confer herbicide resistance to crops through target site mutations at codon positions 1781, 1999, 2027, 2041, 2078, 2088, and 2096 encoding ACCase. Here, Lifeasible introduced the ACCase gene into the chloroplast genome to develop a resistance trait that is highly tolerant to easily metabolized ACCase herbicides.

The development of chloroplast genetic engineering can confer resistance to ACC-inhibiting herbicides through a number of genes. Their widespread use worldwide has selected resistance genes in many grass weed species. Our engineers use biochemistry and molecular biology to determine the herbicidal activity and selectivity of ACC-inhibiting herbicides on crops. In addition, we offer a variety of assays for resistance to ACCase herbicides for you to choose from.

• Discovery and molecular biology techniques of precise nucleotide changes for target drug resistance.
• Methods based on pollen, seeds, enzymes and metabolism.
• A classic whole-plant experiment in which seeds are collected at the end of the growing season.
• Testing begins with plants collected from the field before and after herbicide application.
• Syngenta Resistance Season Rapid (RISQ) trial.

Features of Our Strategy

• ACCase herbicides are mainly used for weed control of dicotyledonous crops, and a small amount of compounds are used in small grain crops and rice.
• ACCase inhibitors show strong potency against grass ACCase activity, but do not inhibit mammalian, fungal or even broadleaf ACCase.
• Resistance depends on plant growth stage, herbicide availability and other environmental conditions.
• Molecular biology techniques have greatly improved the understanding of target resistance.
• Computer-based modeling approach sustains long-term sustainable use of ACCase herbicides.

Amino acid residues are key determinants of herbicide susceptibility to ACCase herbicides, and an understanding of metabolism-based resistance can confer resistance to herbicides with different targets. Lifeasible has extensive knowledge and experience in the engineering of herbicide resistance via herbicide-insensitive enzymes. Our mission is to provide customers with comprehensive, reliable, professional solutions to accelerate your research. If you are interested in our solutions, please contact us at any time.

References

1. Sasaki Y, Nagano Y. (2004) Plant acetyl-CoA carboxylase: structure, biosynthesis, regulation, and gene manipulation for plant breeding[J]. Bioscience, biotechnology, and biochemistry. 68(6): 1175-1184.
2. Délye C. (2005) Weed resistance to acetyl coenzyme A carboxylase inhibitors: an update[J]. Weed Science. 53(5): 728-746.