(Digitaria ciliaris)

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

China, Jiangsu Province
Southern Crabgrass (Digitaria ciliaris) is a monocot weed in the Poaceae family.  In China this weed first evolved resistance to Group 1 (Legacy A) herbicides in 2021 and infests Rice.   Group 1 (Legacy A) herbicides are known as Inhibition of Acetyl CoA Carboxylase (Inhibition of Acetyl CoA Carboxylase ).  Research has shown that these particular biotypes are resistant to metamifop and they may be cross-resistant to other Group 1 (Legacy A) 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.

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QUIK STATS (last updated Mar 30, 2023 )

Common NameSouthern Crabgrass
SpeciesDigitaria ciliaris
GroupInhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
LocationChina, Jiangsu Province
Contributors - (Alphabetically)Hong-Chun Wang 
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Hong-Chun Wang

Mechanism of metamifop resistance in Digitaria ciliaris var. Chrysoblephara from Jiangsu, China.

Author(s) : Cao JingJing ;  Tao Yuan ;  Zhang ZiChang ;  Gu Tao ;  Li Gui ;  Lou YuanLai ;  Wang HongChun

Author Affiliation : Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.

Author Email :

Journal article : Frontiers in Plant Science 2023 Vol.14 No.February ref.40  

Abstract : Digitaria ciliaris var. chrysoblephara is one of the most competitive and problematic grass weeds in China. Metamifop is an aryloxyphenoxypropionate (APP) herbicide that inhibits the activity of acetyl-CoA carboxylase (ACCase) of sensitive weeds. Following the introduction of metamifop to China in 2010, it has been continuously used in rice paddy fields, thereby substantially increasing selective pressure for resistant Dciliaris var. chrysoblephara variants. Here, populations of Dciliaris var. chrysoblephara (JYX-8, JTX-98, and JTX-99) were observed to be highly resistant to metamifop, with resistance index (RI) values of 30.64, 14.38, and 23.19, respectively. Comparison of resistant and sensitive population ACCase gene sequences revealed that a single nucleotide substitution from TGG to TGC resulted in an amino acid substitution from tryptophan to cysteine at position 2,027 in the JYX-8 population. No corresponding substitution was observed for JTX-98 and JTX-99 populations. The ACCase cDNA of Dciliaris var. chrysoblephara was successfully obtained by PCR and RACE methods, representing the first amplification of full length ACCase cDNA from Digitaria spp. Investigation of the relative expressions of ACCase gene revealed the lack of significant differences between sensitive and resistant populations before and after herbicide treatments. ACCase activities in resistant populations were less inhibited than in sensitive populations and recovered to the same or even higher levels compared to untreated plants. Whole-plant bioassays were also conducted to assess resistance to other ACCase inhibitors, acetolactate synthase (ALS) inhibitors, auxin mimic herbicide, and protoporphyrinogen oxidase (PPO) inhibitor. Cross-resistance and some multi-resistance were observed in the metamifop-resistant populations. This study is the first to focus on the herbicide resistance of Dciliaris var. chrysoblephara. These results provide evidence for a target-site resistance mechanism in metamifop-resistant Dciliaris var. chrysoblephara, while providing a better understanding of cross- and multi-resistance characteristics of resistant populations that will help in the management of herbicide-resistant Dciliaris var. chrysoblephara.

ISSN : 1664-462X

DOI : 10.3389/fpls.2023.1133798

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Confirmation Tests

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

Genetic studies on HRAC Group 1 resistant Southern Crabgrass 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 1 (Legacy A) resistant Southern Crabgrass from China indicate that resistance is due to an altered target site.  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 1 (Legacy A) resistant Southern Crabgrass from China please update the database.
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Ph D
University Of Nanjing Agricultural University
Herbicide Research Laboratory
The College Of Plant Protection
Nanjing, 210095, Jiangsu
Email Hong-Chun Wang


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in China have been instrumental in providing you this information. Particular thanks is given to Hong-Chun Wang for providing detailed information.
Herbicide Resistant Southern Crabgrass Globally
(Digitaria ciliaris)
Herbicide Resistant Southern Crabgrass Globally
(Digitaria ciliaris)
Drag a column header and drop it here to group by that column
Herbicide Resistant Southern Crabgrass Globally
(Digitaria ciliaris)
#CountryFirstYearSituationActive IngredientsSite of Action
1 BrazilBrazil 2002 Soybean cyhalofop-butyl, fenoxaprop-ethyl, fluazifop-butyl, haloxyfop-methyl, propaquizafop, and sethoxydim 5 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
225Digitaria ciliarisSouthern Crabgrass5214
2 ChinaChina 2021 Rice metamifop 9 Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
225Digitaria ciliarisSouthern Crabgrass27272
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