Mechanism of action of the 1,2,4-triazolo[1,5-a] pyrimidines |
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Authors: | B Clifford Gerwick Mani V Subramanian Vivian I Loney-Gallant Darrell P Chandler |
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Abstract: | The substituted 1,2,4-triazolo1,5-a]pyrimidines are a new class of highly active herbicides. Protection of Arabidopsis thaliana seedlings from triazolopyrimidine-induced injury by the branched-chain amino acids was observed. Acetolactate synthase (EC 4.1.3.18) was isolated and found to be quite sensitive to inhibition. I50 values for inhibition of the enzyme from a number of plant sources show little variation and no correlation to whole-plant response, suggesting uptake, translocation and metabolism play key roles in modulating herbicidal activity. Further studies indicate that these chemicals are slow, tight-binding inhibitors that are readily dissociated by gel filtration. Some correlations between in-vitro activity and in-vivo activity were observed for ortho-substituted analogs on selected broadleaf species. |
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