<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Bromus sterilis from Czech Republic

International Survey of Herbicide-Resistant Weeds

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Thursday, November 14, 2024

HRAC GROUP 2 (LEGACY B) RESISTANT POVERTY BROME
(Bromus sterilis)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Czech Republic

INTRODUCTION		POVERTY BROME
Poverty Brome (Bromus sterilis) is a monocot weed in the Poaceae family. In Czech Republic this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2017 and infests Wheat. Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ). Research has shown that these particular biotypes are resistant to propoxycarbazone-Na, pyroxsulam, and sulfometuron-methyl and they may be cross-resistant to other Group 2 (Legacy B) 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 25, 2021 )
Common Name	Poverty Brome
Species	Bromus sterilis
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	propoxycarbazone-Na, pyroxsulam, and sulfometuron-methyl
Location	Czech Republic
Year	2017
Situation(s)	Wheat
Contributors - (Alphabetically)	Katerina Hamouzova, Pavlína Košnarová, Jakub Mikulka, Madhab Kumar Sen, and Josef Soukup
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NOTES ABOUT THIS BIOTYPE

GENERAL

Katerina Hamouzova

Enhanced metabolism and target gene overexpression confer resistance against acetolactate synthase‐inhibiting herbicides in Bromus sterilis
Madhab Kumar Sen Katerina Hamouzová Jakub Mikulka Rohit Bharati Pavlina Košnarová Pavel Hamouz Amit Roy Josef Soukup
Pest Management Science. First published: 17 December 2020 https://doi.org/10.1002/ps.6241

Abstract
BACKGROUND
Intensive application of acetolactate synthase (ALS)‐inhibiting herbicides has resulted in herbicide‐resistance in many weeds, including Bromus sterilis. The present study was conducted to identify the mechanisms conferring resistance to ALS‐inhibiting herbicides in a Bromus sterilis biotype.

RESULTS
Dose–response studies revealed the resistant biotype to be 288 times less sensitive to pyroxsulam than the susceptible biotype. Furthermore, experiment with a single‐dose, proved this biotype was also cross‐resistant to propoxycarbazone, iodosulfuron plus mesosulfuron and sulfosulfuron. Prior treatment with malathion, a known inhibitor of cytochrome P450s, reduced the level of resistance to pyroxsulam. No mutations were detected from the partial ALS gene sequencing. Flow cytometry and chromosome counting rejected ploidy level variation between the susceptible and resistant biotypes. Relative copy number variation ruled out gene amplification. Quantitative real‐time polymerase chain reaction (PCR) detected a significant difference in ALS gene expression between the susceptible and resistant biotypes.

CONCLUSIONS
Target gene overexpression and enhanced metabolism by cytochrome P450s are likely mechanisms of resistance to pyroxsulam in Bromus sterilis. The current findings highlight the need to monitor additional brome populations for herbicide resistance in Europe and endorse the need for alternate herbicides in integrated weed management to delay the possible evolution of herbicide resistance in these species.

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MECHANISM

Katerina Hamouzova

No already reported target site mutations were detected. But, ALS gene over-expression was found for this biotype, when compared with the sensitive biotype.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Poverty Brome biotype with this Poverty Brome 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 HRAC Group 2 resistant Poverty Brome 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

Studies on the mechanism of resistance of Group 2 (Legacy B) resistant Poverty Brome from Czech Republic indicate that resistance is due to enhanced metabolism, and gene amplification. There may be a note below or an article discussing the mechanism of resistance in the Fact Sheets and Other Literature

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 2 (Legacy B) resistant Poverty Brome from Czech Republic please update the database.

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CONTRIBUTING WEED SCIENTISTS

KATERINA HAMOUZOVA

Weed Research Scientist Czech University Of Agriculture In Prague Depart. Of Agroecology And Biometeorology Kamycka 129 Prague, 6 - Suchdol, 16521, Prague Czech Republic Email Katerina Hamouzova Web : Web Site Link

PAVLÍNA KOŠNAROVÁ

Researcher Czech University of Life Sciences Agroecology and Plant Production Kamycka 129 Prague , 16500, Czech Republic Czech Republic Email Pavlína Košnarová Web : Web Site Link

JAKUB MIKULKA

Ing. Weed Research Department of Agroecology and Crop Production Internacionální 1277 Prague, 16000, Prague Czech Republic Email Jakub Mikulka Web : Web Site Link

MADHAB KUMAR SEN

Ing. Czech university of life sciences Prague Department of Agroecology and Crop Production Kamýcká 129 Prague 6- Suchdol, 16500 Prague, 16500, Prague Czech Republic Email Madhab Kumar Sen Web : Web Site Link

JOSEF SOUKUP

Professor Czech University of Life Sciences Prague Agroecology and Biometeorology Kamycka 129 Prague 6 - Suchdol, 16521, Prague Czech Republic Email Josef Soukup Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Czech Republic have been instrumental in providing you this information. Particular thanks is given to Katerina Hamouzova, Pavlína Košnarová, Jakub Mikulka, Madhab Kumar Sen, and Josef Soukup for providing detailed information.

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Herbicide Resistant Poverty Brome Globally
(Bromus sterilis)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Czech Republic

2017

Wheat

propoxycarbazone-Na, pyroxsulam, and sulfometuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

France

2009

Wheat

iodosulfuron-methyl-Na, mesosulfuron-methyl, propoxycarbazone-Na, and pyroxsulam

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Germany

2012

Cereals, and Rapeseed

cycloxydim, and propaquizafop

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

Germany

2017

Wheat

propoxycarbazone-Na

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United Kingdom

2020

Wheat

iodosulfuron-methyl-Na, mesosulfuron-methyl, and pyroxsulam

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

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Cite this site as: Heap, I. The International Survey of Herbicide Resistant Weeds. Online. Internet. Thursday, November 14, 2024 . Available www.weedscience.org
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