INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE
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GROUP B/2 resistance: (ALS INHIBITORS)
Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)
MUTATION: SERINE 653 to THREONINE
) is a monocot plant in the poaceae family. A single amino acid substitution from Serine 653 to Threonine has led to resistance to ALS inhibitors as indicated in the table below.
Resistant > 10 fold
The cross-resistance pattern may be obscured by the co-occurrence of non-target-site resistance in the population (see Beckie et al. 2012).
Beckie, H. J. ; Warwick, S. I. ; Sauder, C. A.
Basis for herbicide resistance in Canadian populations of wild oat (
10 - 18
Wild oat is the second-most abundant, but most economically important, weed across the Canadian Prairies of western Canada. Despite the serious economic effects of resistance to acetyl-CoA carboxylase (ACC) or acetolactate synthase (ALS) inhibitors or both in this weed throughout the Northern Great Plains of North America, little research has examined the basis for herbicide resistance. We investigated target-site and nontarget-site mechanisms conferring ACC- and ALS-inhibitor resistance in 16 wild oat populations from across western Canada (four ACC-inhibitor resistant, four ALS-inhibitor resistant, and eight ACC- and ALS-inhibitor resistant). The
mutations were found in 8 of the 12 ACC inhibitor-resistant populations. The Ile1781Leu mutation was detected in three populations, the Trp2027Cys and Asp2078Gly mutations were in two populations each, and the Trp1999Cys, Ile2041Asn, Cys2088Arg, and Gly2096Ser substitutions were in one population each. Three populations had two
mutations. Only 2 of the 12 ALS inhibitor-resistant populations had an
target-site mutation - Ser653Thr and Ser653Asn substitutions. This is the first global report of
target-site mutations in
spp. and four previously undocumented
mutations in wild oat. Based on these molecular analyses, seedlings of five ACC+ALS inhibitor-resistant populations (one with an
mutation; four with no
mutations) were treated with malathion, a known cytochrome P450 monooxygenase inhibitor, followed by application of one of four ACC- or ALS-inhibiting herbicides. Malathion treatment often resulted in control or suppression of these populations, suggesting involvement of this enzyme system in contributing to resistance to both ACC and ALS inhibitors.
This case was entered by Patrick Tranel Email:
PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I. The International Herbicide-Resistant Weed Database. Online.
Friday, October 30, 2020
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