Use of ketol-acid reductoisomerase inhibitors to prevent or treat fungal infection of plants
The invention concerns the use of ketol-acid reductoisomerase inhibitors for treating fungal diseases affecting crops. The invention concerns methods for treating crops against fungal diseases comprising applying a ketol-acid reductoisomerase inhibitor. The invention also concerns methods for identifying novel fungicidal compounds comprising a step which consists in identifying ketol-acid reductoisomerase inhibitors.
1. A method for identifying a fungicidal compound, comprising:
a) contacting a ketol-acid reductoisomerase with a test compound under conditions required for ketol-acid reductoisomerase enzymatic activity and in the presence of a substrate, wherein the ketol-acid reductoisomerase comprises an amino acid sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, and SEQ ID NO:3 and
b) measuring the ketol-acid reductoisomerase enzymatic activity;
wherein inhibition of ketol-acid reductoisomerase activity by the test compound indicates that the test compound is a fungicidal compound.
2. The method of claim 1 , further comprising determining whether said compound that inhibits the enzymatic activity of a ketol-acid reductoisomerase inhibits fungal growth and pathogenesis.
3. The method of claim 1 , wherein
the ketol-acid reductoisomerase is contacted with the test compound in the presence of magnesium and NADPH.
4. The method of claim 1 , wherein said substrate is 2-acetolactate (AL) or 2-aceto-2-hydroxybutyrate (AHB).
5. The method of claim 1 , wherein said measuring the ketol-acid reductoisomerase enzymatic activity comprises measuring the decrease in absorption of NADPH at 340 nm.
6. A method for identifying a fungicidal compound comprising:
a) expressing in a host organism a ketol-acid reductoisomerase comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1, SEQ ID NO:2, and SEQ ID NO:3;
b) purifying the ketol-acid reductoisomerase produced by said host organism;
c) under conditions required for ketol-acid reductoisomerase enzymatic activity and in the presence of a substrate, contacting a test compound with said purified ketol-acid reductoisomerase; and
d) measuring the ketol-acid reductoisomerase enzymatic activity,
wherein inhibition of ketol-acid reductoisomerase activity by the test compound indicates that the test compound is a fungicidal compound.
7. The method of claim 6 , wherein said substrate is 2-acetolactate (AL) or 2-aceto-2-hydroxybutyrate (AHB).
8. The method of claim 6 , wherein said measuring the ketol-acid reductoisomerase enzymatic activity comprises measuring a decrease in absorption of NADPH at 340 nm.