Group B/2 resistant Salsola tragus from Canada, Alberta

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

GROUP B/2 RESISTANT RUSSIAN-THISTLE
(Salsola tragus)

ALS inhibitors (B/2)

Canada, Alberta

INTRODUCTION		RUSSIAN-THISTLE
Russian-thistle (Salsola tragus) is a dicot weed in the Chenopodiaceae family. In Alberta this weed first evolved resistance to Group B/2 herbicides in 2007 and infests Spring Barley, and Wheat. Group B/2 herbicides are known as ALS inhibitors (Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)). Research has shown that these particular biotypes are resistant to thifensulfuron-methyl, and tribenuron-methyl and they may be cross-resistant to other Group B/2 herbicides. The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS (last updated Jan 19, 2014 )
Common Name	Russian-thistle
Species	Salsola tragus
Group	ALS inhibitors (B/2)
Herbicides	thifensulfuron-methyl, and tribenuron-methyl
Location	Canada, Alberta
Year	2007
Situation(s)	Spring Barley, and Wheat
Contributors - (Alphabetically)	Hugh Beckie
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Russian-thistle biotype with this Russian-thistle biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

Genetic studies on Group B/2 resistant Russian-thistle have not been reported to the site. There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature

Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of Group B/2 resistant Russian-thistle from Alberta please update the database.

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CONTRIBUTING WEED SCIENTISTS

HUGH BECKIE

Research Scientist Agriculture & Agri-Food Canada, Science & Technology Branch Herbicide-Resistant & Novel-Trait Plants 107 Science Place Saskatoon, S7N 0X2, Saskatchewan Canada Email Hugh Beckie

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Alberta have been instrumental in providing you this information. Particular thanks is given to Hugh Beckie for providing detailed information.

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Herbicide Resistant Russian-thistle Globally
(Salsola tragus)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Canada (Saskatchewan)

1989

Wheat

chlorsulfuron

ALS inhibitors (B/2)

Canada (Alberta)

2007

Spring Barley, and Wheat

thifensulfuron-methyl, and tribenuron-methyl

ALS inhibitors (B/2)

United States (Washington)

1987

Wheat

chlorsulfuron

ALS inhibitors (B/2)

United States (Montana)

1987

Cropland, and Wheat

chlorsulfuron

ALS inhibitors (B/2)

United States (Idaho)

1990

Wheat

chlorsulfuron

ALS inhibitors (B/2)

United States (Oregon)

1993

Wheat

chlorsulfuron, metsulfuron-methyl, and triasulfuron

ALS inhibitors (B/2)

United States (California)

1994

Roadsides

chlorsulfuron, and sulfometuron-methyl

ALS inhibitors (B/2)

United States (Montana)

2015

Fallow, and Wheat

glyphosate

EPSP synthase inhibitors (G/9)

United States (Washington)

2015

Fallow

glyphosate

EPSP synthase inhibitors (G/9)

United States (Oregon)

2016

Fallow

glyphosate

EPSP synthase inhibitors (G/9)

Literature about Similar Cases

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Warwick, S. I. ; Sauder, C. A. ; Beckie, H. J.. 2010. Acetolactate synthase (ALS) target-site mutations in ALS inhibitor-resistant Russian thistle (Salsola tragus). Weed Science 58 : 244 - 251.

ALS inhibitor-resistant biotypes are the fastest growing class of herbicide-resistant (HR) weeds. A Canadian ALS inhibitor-resistant biotype of Russian thistle was first reported in 1989. The molecular basis for ALS-inhibitor resistance is unknown for Canadian populations of this polyploid weed species, and was determined in this study for one Alberta and two Saskatchewan HR Russian thistle populations. HR plants survived spray application of the ALS-inhibitor mixture thifensulfuron:tribenuron in the greenhouse. All three HR Russian thistle populations were heterogeneous and contained both HR and herbicide-susceptible (HS) individuals. The molecular basis for resistance was determined by sequencing the ALS gene and/or conducting a TaqMan genotyping assay for single nucleotide polymorphism (SNP) for the Trp₅₇₄Leu mutation. Two target-site mutations were observed: Trp₅₇₄Leu in all three biotypes (554 individuals) and Pro₁₉₇Gln in one biotype (one individual), suggesting multiple-founding events for Russian thistle HR populations in western Canada. Segregation patterns among F1 and F2 progeny arrays of HR lines sprayed under greenhouse conditions varied; some segregated (i.e., had HR and HS progeny), whereas other lines were exclusively HR. In contrast, no segregation of molecular types, i.e., Trp₅₇₄, Trp/Leu₅₇₄ and Leu₅₇₄, as would be expected with heterozygosity at a single locus Trp/Leu₅₇₄, was observed. Such lack of segregation is consistent with the polyploid genome structure of Russian thistle and the presence of two copies of the ALS gene. The presence of more than one ALS gene confounded the ability of the molecular techniques to accurately identify "true" heterozygotes in this study..

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