Patterns of Cross‐Tolerance to Herbicides Inhibiting Acetohydroxyacid Synthase in Commercial Corn Hybrids Designed for Tolerance to Imidazolinones

Siehl, Daniel L.; Bengtson, Ann; Brockman, J. P.; Butler, John H.; Kraatz, Gary W.; Lamoreaux, Robert J.; Subramanian, Mani

doi:10.2135/cropsci1996.0011183x003600020010x

Cited by 24 publications

(14 citation statements)

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“…A guanine to adenine mutation at position 349 of the gene encoded the Ala 122 Thr substitution that was found in individuals from redroot pigweed population Caledonia 43 and Powell amaranth populations McKillop 9, Brigden 33, Brigden 36, and Brigden 39. This amino acid substitution has previously been reported in field-selected common cocklebur and eastern black nightshade (Solanum ptycanthum L.) and in laboratory-selected mutants of sugar beet (Beta vulgaris L.), tobacco, and corn (Bernasconi et al 1996;Chong and Choi 2000;Milliman et al 2003;Siehl et al 1996;Wright et al 1998). It is generally agreed that this mutation confers resistance to IMI herbicides but not to SUs (Tranel and Wright 2002).…”

Section: Amino Acid Substitutions Conferring Resistancesupporting

confidence: 52%

Mutations inALSconfer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii)

et al. 2005

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A number of redroot pigweed and Powell amaranth populations from various locations in Ontario, Canada, have distinct patterns of resistance to the acetolactate synthase–inhibiting herbicides imazethapyr and thifensulfuron. This suggested the presence of diverse ALS gene mutations among these populations. Seven polymerase chain reaction primer pairs were used to amplify the gene to obtain full sequence information and to determine the identity of resistance-conferring mutations. There was a high degree of similarity in the ALS gene of the two species with only five nucleotides and one amino acid differing. A total of four herbicide resistance-conferring mutations were identified in the two species. The Ala122Thr, Ala205Val, and Trp574Leu amino acid substitutions were found in redroot pigweed whereas Ala122Thr, Trp574Leu, and Ser653Thr were detected in Powell amaranth. The pattern of resistance known to be conferred by the mutations concurred with the resistance level observed at the whole plant level. Distinct mutations being found in geographically separated populations suggest that selection for resistance occurred simultaneously in different locations. It reinforces the fact that resistance to ALS inhibitors is easily selected and that growers need to take this into account when formulating weed management strategies.

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Section: Amino Acid Substitutions Conferring Resistancesupporting

confidence: 52%

Mutations inALSconfer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii)

et al. 2005

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“…Neither of these Arabidopsis mutations showed resistance to the sulfonylurea herbicide chlorsulfuron at twice the I 100 concentration. The equivalent mutations to Ala-122-Thr in X. strumarium (Bernasconi et al, 1995), maize (Siehl et al, 1996), and sugar beet (Beta vulgaris; Wright and Penner, 1998) also confer only imidazolinone resistance. In contrast, the equivalent changes in yeast ALS (Ala-117-Thr and Ala-200-Val) result in sulfonylurea resistance, but not imidazolinone resistance (Falco et al, 1989).…”

Section: Discussionmentioning

confidence: 99%

Ethylmethanesulfonate Saturation Mutagenesis in Arabidopsis to Determine Frequency of Herbicide Resistance

Jander¹,

Baerson

Hudak³

et al. 2003

Plant Physiol.

147

107

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Plant resistance to glyphosate has been reported far less frequently than resistance to sulfonylurea and imidazolinone herbicides. However, these studies tend to be anecdotal, without side by side comparisons for a single species or natural isolate. In this study, we tested the frequencies of resistance of three herbicides in a controlled ethylmethanesulfonate (EMS) saturation mutagenesis experiment, allowing a direct comparison of the frequencies at which resistant mutant plants arise. The 100% growth inhibition dose rates of glyphosate, chlorsulfuron (a sulfonylurea herbicide), and imazethapyr (an imidazolinone herbicide) were determined for Arabidopsis. Populations of EMS-mutagenized M 2 seedlings were sprayed with twice the 100% growth inhibition dose of glyphosate, chlorsulfuron, or imazethapyr, and herbicide-resistant mutants were identified. Although there were no glyphosate-resistant mutants among M 2 progeny of 125,000 Columbia and 125,000 Landsberg erecta M 1 lines, chlorsulfuron resistance and imazethapyr resistance each appeared at frequencies of 3.2 ϫ 10 Ϫ5 . Given the observed frequency of herbicide resistance mutations, we calculate that there are at least 700 mutations in each EMS-mutagenized Arabidopsis line and that fewer than 50,000 M 1 lines are needed to have a 95% chance of finding a mutation in any given G:C base pair in the genome. As part of this study, two previously unreported Arabidopsis mutations conferring resistance to imidazolinone herbicides, csr1-5 (Ala-122-Thr) and csr1-6 (Ala-205-Val), were discovered. Neither of these mutations caused enhanced resistance to chlorsulfuron in Arabidopsis.Spontaneous herbicide resistance is generally thought to occur within weed populations as a consequence of the intense selective pressure exerted by a lack of diversity in weed management practices (Gressel and Segel, 1978). Factors such as extended residual soil activity, lack of rotation to other herbicidal modes of action, and specific managerial practices further discriminate between resistant and susceptible individuals within a population (Powles and Holtum, 1994). In addition, the rate and severity at which resistant weed infestations occur is influenced by genetic and ecophysiological determinants such as the mode of inheritance of a given resistance mechanism, the absence or presence of fitness penalties associated with resistance, and the reproductive habit of a given weed species (Gressel and Segel, 1978;Jasieniuk et al., 1996; Gardner et al., 1998). To date, more than 261 herbicide-resistant weed biotypes exist distributed among 52 different countries, involving at least 17 different herbicide modes of action (Heap, 2002). Because application rate and other factors vary greatly in the field, it is difficult to make a direct comparison of the frequencies at which weeds develop resistance to different herbicides. To circumvent this problem, we have used a controlled laboratory setting to compare the frequencies at which heavily mutagenized populations of Arabidopsis develop resistanc...

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“…Mutation Ser653‐to‐Asn653, occurring in XI12, QJ22, and mutant 2, confers only tolerance to imidazolinones (Table 1). 30, 36, 41, 42, 46 In contrast, mutation Trp574‐to‐Leu574 of XA17 confers tolerance not only to imidazolinones but also to all other families of AHAS inhibitors including sulfonylureas, triazolopyrimidines, and pyrimidinylthio‐benzoates 22, 36, 42, 45–48. Mutation Ala155‐to‐Thr155 confers tolerance to imidazolinones and pyrimidinylthiobenzoates but not to sulfonylureas or triazolopyrimidines 22, 45, 47.…”

Section: Commercialized Imidazolinone‐tolerant Cropsmentioning

confidence: 99%

Imidazolinone‐tolerant crops: history, current status and future

Tan¹,

Evans²,

Dahmer³

et al. 2004

Pest Management Science

469

366

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Imidazolinone herbicides, which include imazapyr, imazapic, imazethapyr, imazamox, imazamethabenz and imazaquin, control weeds by inhibiting the enzyme acetohydroxyacid synthase (AHAS), also called acetolactate synthase (ALS). AHAS is a critical enzyme for the biosynthesis of branched-chain amino acids in plants. Several variant AHAS genes conferring imidazolinone tolerance were discovered in plants through mutagenesis and selection, and were used to create imidazolinone-tolerant maize (Zea mays L), wheat (Triticum aestivum L), rice (Oryza sativa L), oilseed rape (Brassica napus L) and sunflower (Helianthus annuus L). These crops were developed using conventional breeding methods and commercialized as Clearfield* crops from 1992 to the present. Imidazolinone herbicides control a broad spectrum of grass and broadleaf weeds in imidazolinone-tolerant crops, including weeds that are closely related to the crop itself and some key parasitic weeds. Imidazolinone-tolerant crops may also prevent rotational crop injury and injury caused by interaction between AHAS-inhibiting herbicides and insecticides. A single target-site mutation in the AHAS gene may confer tolerance to AHAS-inhibiting herbicides, so that it is technically possible to develop the imidazolinone-tolerance trait in many crops. Activities are currently directed toward the continued improvement of imidazolinone tolerance and development of new Clearfield* crops. Management of herbicide-resistant weeds and gene flow from crops to weeds are issues that must be considered with the development of any herbicide-resistant crop. Thus extensive stewardship programs have been developed to address these issues for Clearfield* crops.

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Patterns of Cross‐Tolerance to Herbicides Inhibiting Acetohydroxyacid Synthase in Commercial Corn Hybrids Designed for Tolerance to Imidazolinones

Cited by 24 publications

References 0 publications

Mutations inALSconfer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii)

Mutations inALSconfer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii)

Ethylmethanesulfonate Saturation Mutagenesis in Arabidopsis to Determine Frequency of Herbicide Resistance

Imidazolinone‐tolerant crops: history, current status and future

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