Corn poppy (Papaver rhoeas) cross‐resistance to ALS‐inhibiting herbicides

Abstract

These findings indicate that Pro(197) substitution by Ala, Ser, Arg or Thr in corn poppy results in a less sensitive ALS enzyme to sulfonylurea herbicides than to other ALS-inhibiting herbicides. The continued use of sulfonylurea herbicides led to cross-resistance to all ALS-inhibiting herbicides, making their use impossible in corn poppy resistance management programmes.

Mutation at residue 376 of ALS confers tribenuron-methyl resistance in flixweed (Descurainia sophia) populations from Hebei Province, China

“…Currently, six conserved-region amino acid mutations in the ALS are generally accepted to confer ALSinhibitor resistance in weed populations, including Ala122, Pro197, Ala205, Asp376, Trp574, and Ser653 [9]. Nevertheless, Pro197 mutation is the most common site for ALS-inhibitor resistance in weed species, such as Alopecurus japonicus [30], Anthemis cotula [31] and Papaver rhoeas [32]. Mutations of Pro197 to Ser and Thr are by far the most common [33].…”

A novel Pro197Glu substitution in acetolactate synthase (ALS) confers broad-spectrum resistance across ALS inhibitors

“…Pro197 mutations confer resistance to SUs and TPs; Ala122, Ser653 and Gly654 mutations confer resistance to IMIs; and Asp376 and Trp574 mutations confer broad-spectrum resistance to all five classes of ALS inhibitors [12][13][14]. Although Pro197 mutations usually result in SU but not IMI resistance [29], resistance to IMI herbicides has also been observed in several weed species due to the expression of an insensitive form of ALS resulting from a substitution at position 197 [16,[30][31][32][33][34][35][36]. A new discovery now demonstrates that the cross-resistance pattern endowed by a target-site mutation depends on the substitution position, the specific substitutions, and, sometimes, the weed species [14].…”

Effects of resistance mutations of Pro197, Asp376 and Trp574 on the characteristics of acetohydroxyacid synthase (AHAS) isozymes

“…These resistance mutations cause weed resistance by altering the characteristics of the AHAS enzyme, such as reducing catalytic activity and herbicide affinity or increasing affinity for the substrate pyruvate. In rare cases, a few weed species with specific resistance mutations exhibit hypersensitivity to other AHAS‐inhibiting herbicides. Resistance mutations at different sites in AHAS may confer resistance (or cross‐resistance) to different herbicide groups.…”