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An in vivo Acetolactate Synthase Assay

  • David M. Simpson (a1), Edward W. Stoller (a2) and Loyd M. Wax (a2)


A method was developed and tested for in vivo assay of acetolactate synthase (ALS). The method used foliar application of 1,1-cyclopropanedicarboxylic acid (CPCA) to inhibit ketol-acid reductoisomerase, the enzyme immediately following ALS in biosynthesis of branched-chain amino acids, thereby causing accumulation of acetolactate. Since the amount of acetolactate accumulation is a function of carbon flux through ALS, quantification of acetolactate accumulation determined ALS activity. Accumulation of acetolactate in soybean leaves resulted from CPCA rates as low as 15 g/ha and occurred within 1.5 h. Accumulation rates in soybean leaflets declined with leaf age from 84 μg/h/g tissue at 3 d to 17 μg/h/g tissue at 7 d. Foliar application of CPCA also caused acetolactate accumulation in corn, grain sorghum, velvetleaf, common cocklebur, and smooth pigweed. The ability of the in vivo assay to quantify the reduction in ALS activity following applications of ALS-inhibiting herbicides was validated by comparing ALS activity following thifensulfuron application to ‘Williams 82’ soybean, which has a sulfonylurea-sensitive ALS, and ‘Asgrow 3200’ soybean, which has a sulfonylurea-insensitive ALS. Thifensulfuron reduced ALS activity in Williams 82 soybean to 0, 0.8, 3.3, and 15.6% of the CPCA control at 6, 12, 24, and 48 HAT, but ALS activity in Asgrow 3200 soybean was reduced only to 34, 40, 57, and 88% of the CPCA control.



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1. Ahrens, W. H. 1990. Enhancement of soybean (Glycine max) injury and weed control by thifensulfuron-insecticide mixtures. Weed Technol. 4:524528.
2. Beckett, T. H. and Stoller, E. W. 1991. Effects of methylammonium and urea ammonium nitrate on foliar uptake of thifensulfuron in velvetleaf. Weed Sci. 39:333338.
3. Beyer, E. M., Duffy, M. J., Hay, J. V., and Schlueter, D. D. 1988. Sulfonylurea. p. 117189 in Kearney, P. C. and Kaufman, D. D., eds. Herbicides: Chemistry, Degradation, and Mode of Action, Vol. 3., Marcel Dekker Inc., New York.
4. Biediger, D. L., Baumann, P. A., Weaver, D. N., Chandler, J. M., and Merkle, M. G. 1992. Interactions between primisulfuron and selected soil-applied insecticides in corn (Zea mays). Weed Technol. 6:807812.
5. Brown, H. M., Brattsten, L. B., Lilly, D. E., and Hanna, P. J. 1993. Metabolic pathways and residue levels of thifensulfuron methyl in soybean. J. Agric. Food Chem. 41:17241730.
6. Brown, H. M. and Kearney, P. C. 1991. Plant biochemistry environmental properties, global impact of the sulfonylurea herbicides. p. 3249 in Baker, D. R., Fenyes, J. G., and Mobery, W. K., eds. Synthesis and Chemistry of Agrochemicals II., Am. Chem. Soc., Washington D.C.
7. Brown, H. M. 1990. Mode of action, crop selectivity, and soil relations of the sulfonylurea herbicides. Pestic. Sci. 29:263281.
8. Brown, H. M., Wittenbach, V. A., Forney, D. R., and Strachan, S. D. 1990. Basis for soybean tolerance to thifensulfuron methyl. Pestic. Biochem. Physiol. 37:303313.
9. Devine, M. D., Duke, S. O., and Fedtke, C. 1993. Physiology of Herbicide Action. Prentice-Hall, Englewood Cliffs, NJ. p. 251281.
10. Diehl, K. E., Simpson, D. M., Taylor, S. L., Stoller, E. W., and Wax, L. M. 1994. Effect of soil organic matter on the interaction between nicosulfuron and terbufos in corn. Weed Sci. In Press.
11. Fielding, R. S. and Stoller, E. W. 1990. Effects of additives on the efficacy, uptake, and translocation of the methyl ester of thifensulfuron. Weed Sci. 38:172178.
12. Fielding, R. S. and Stoller, E. W. 1990. Effects of additives on the efficacy, uptake, and translocation of chlorimuron ethyl ester. Weed Technol. 4:264271.
13. Frazier, T. L., Nissen, S. J., Mortensen, D. A., and Meinke, L. J. 1993. The influence of terbufos on primisulfuron absorption and fate in corn. Weed Sci. 41:664668.
14. Gerwick, B. C., Mireles, L. C., and Eilers, R. J. 1993. Rapid diagnosis of ALS/AHAS-resistant weeds. Weed Technol. 7:519524.
15. Kent, L.M., Wills, G.D., and Shaw, D.R. 1991. Effect of ammonium sulfate, imazapyr, temperature, and relative humidity on the absorption and translocation of imazethapyr. Weed Sci. 39:412416.
16. Ray, T. B. 1984. Site of action of chlorsulfuron: inhibition of valine and isoleucine biosynthesis in plants. Plant Physiol. 75:827831.
17. Sebastian, S. A., Fader, G. M., Ulrich, J. F., Forney, D. R., and Chaleff, R. S. 1989. Semidominant soybean mutation for resistance to sulfonylurea herbicide. Crop Sci. 29:14031408.
18. Singh, B. K., Stidham, M. A., and Shaner, D. L. 1988. Separation and characterization of two forms of acetohydroxy acid synthase from black mexican sweet corn cells. J. Chromatogr. 444:251261.
19. Stidham, M. A. and Singh, B. K. 1991. Imidazolinone-acetohydoxyacid synthase interactions. p. 7190 in Shaner, D. L. and O'Connor, S. L., eds. The Imidazolinone Herbicides. CRC Press, Boston, MA.
20. Stidham, M. A. 1990. Herbicides that inhibit acetohydroxyacid synthase. Weed Sci. 39:428434.
21. Sweetser, P. B., Scho, G. S., and Hutchinson, J. M. 1982. Metabolism of chlorsulfuron by plants: biological basis for selectivity of a new herbicide for cereals. Pestic. Biochem. Physiol. 17:1823.



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