Acetohydroxyacid synthase (AHAS) is one of the most important herbicide target enzymes. The intensive and extensive use of such herbicides has led to an alarming increase in the evolution of resistance. Understanding the resistance mechanism for AHAS mutants is necessary for the rational design of the herbicides and the selection or engineering of herbicide-tolerant crops. A set of mutated E. coliAHAS II was constructed and overexpressed in our lab. The apparent inhibition constants for some commercial herbicides, such as chlorimuron ethyl, bispyribac, chlorsulfuron and sulfometuron methyl, against these AHAS mutants were measured. Based on these data, we employed the MB-QSAR method, which we established recently, to quantitatively predict herbicide resistance and to decipher the structure resistance relationships for these AHAS mutants against these herbicides. The comparison of the molecular interaction diagrams from MB-QSAR models lead to insights about which positions in the polypeptide chain have a higher propensity to acquire herbicide resistant mutations,which in turn can be translated into guidelines for modifying the existing herbicide as well as for designing new drugs.

Quantitative herbicide resistance by acetohydroxyacid synthase

248th National Meeting (2014)

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