<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Monochoria korsakowii from China

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 2 (LEGACY B) RESISTANT MIZUAOI (JPN)/MOOLOKZAM (KOR)
(Monochoria korsakowii)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

China, Jilin

INTRODUCTION		MIZUAOI (JPN)/MOOLOKZAM (KOR)
Mizuaoi (JPN)/Moolokzam (KOR) (Monochoria korsakowii) is a monocot weed in the Pontederiaceae family. In China this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2003 and infests Rice. 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 bensulfuron-methyl, and pyrazosulfuron-ethyl 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 Jul 10, 2007 )
Common Name	Mizuaoi (JPN)/Moolokzam (KOR)
Species	Monochoria korsakowii
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	bensulfuron-methyl, and pyrazosulfuron-ethyl
Location	China, Jilin
Year	2003
Situation(s)	Rice
Contributors - (Alphabetically)	Tae Seon Park
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ACADEMIC ASPECTS

Confirmation Tests

Field, Greenhouse, and Laboratory trials comparing a known susceptible Mizuaoi (JPN)/Moolokzam (KOR) biotype with this Mizuaoi (JPN)/Moolokzam (KOR) 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 Mizuaoi (JPN)/Moolokzam (KOR) indicate that the inheritance is determined by a one gene, dominant, nuclear trait. 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 Mizuaoi (JPN)/Moolokzam (KOR) 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

Researchers have indicated that Group 2/B resistant Mizuaoi (JPN)/Moolokzam (KOR) is ecologically less fit than normal susceptible Mizuaoi (JPN)/Moolokzam (KOR). There may be a note below or an article discussing the fitness of this biotype in the Fact Sheets and Other Literature

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CONTRIBUTING WEED SCIENTISTS

TAE SEON PARK

Physiology Of Herbicide Action National Institute Of Agricultural Science And Technology Department Of Crop Protection Dept of Plant Sciences 51 Campus Dr., Suweon, 441-707 South Korea Email Tae Seon Park

ACKNOWLEDGEMENTS
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 Tae Seon Park for providing detailed information.

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Herbicide Resistant Mizuaoi (JPN)/Moolokzam (KOR) Globally
(Monochoria korsakowii)

Country

FirstYear

Situation

Active Ingredients

Site of Action

China

2003

Rice

bensulfuron-methyl, and pyrazosulfuron-ethyl

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

Japan

1994

Rice

bensulfuron-methyl, imazosulfuron, and pyrazosulfuron-ethyl

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

South Korea

1998

Rice

bensulfuron-methyl

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

Literature about Similar Cases

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Wu MingGen ; Jin WanHe ; Xu YongNan. 2011. Development of allele-specific PCR for detection of herbicide-resistance in Monochoria korsakowii Regel et Maack. Journal of Anhui Agricultural University 38 : 296 - 298.

Allele-specific PCR is a rapid, simple, and low-cost method for single-nucleotide polymorphism identification. Using this technique, a single-nucleotide polymorphism primer marker of thymine(susceptible) or guanine(resistant) at the 3′end on 592 point of ALS (acetolactate synthetase) gene encoding site (197 point of ALS amino acid) was designed to detect the herbicide-resistant type of Monochoria korsakowii Regel et Maack. in Yanbian region. The result shows that susceptibility primer marker can be used to detect the susceptibility biotype; otherwise can be detected resistant biotype; the cause of resistance to sulfonylurea herbicide type can be induced by substitution of Pro₁₉₇ to histidine. It proved that the technique was efficient and feasible to detect ALS gene of herbicide-resistant type..

Lu ZongZhi ; Zhang ChaoXian ; Fu JunFan ; Li MaoHai ; Li GuiJun. 2009. Molecular basis of resistance to bensulfuron-methyl in Monochoria korsakowii. Scientia Agricultura Sinica 42 : 3516 - 3521.

Objective: In recent years, Monochoria korsakowii has been a serious problem in paddy fields in northeast of China. It has become a weed which is very difficult to control by bensulfuron-methyl in some areas in the region. The objective of this study is to understand the molecular basis of the resistance mechanism to bensulfuron-methyl in Monochoria korsakowii and to find the specific mutation sites in amino acid sequence of acetolactate synthase (ALS) in the resistant Monochoria korsakowii biotype. Method: Using the PCR method, fragments that encode the ALS were cloned from Monochoria korsakowii, susceptible (S) and resistant (R) biotypes to bensulfuron-methyl respectively, and sequenced subsequently. Result: The result showed that the nucleotide sequence of R M. korsakowii biotype differed from that of the S biotype by three nucleotide substitutions, that were proline (Pro) 197 substituted by histidine (His), methionine (Met) 200 by valine (Val), and arginine (Arg) 388 by histidine (His), among those, the amino acid substitution of Pro₁₉₇ (CCT) to His (CAT) had been reported in many other resistant weeds. Conclusion: It is clear that the substitution of Pro ₁₉₇ may be responsible for the resistance to bensulfuron-methyl in the R M. korsakowii biotype. The functions of the other two mutations in the R biotype need to be further investigated..

Lu ZongZhi ; Zhang ChaoXian ; Fu JunFan ; Li GuiJun. 2009. Resistant Monochoria korsakowii biotypes to bensulfuron-methyl and their acetolactate synthase sensitivity. Acta Phytophylacica Sinica 36 : 354 - 358.

In order to evaluate the resistance of Monochoria korsakowii to bensulfuron-methyl in rice grown regions, Liuhe and Dehui, in Jilin Province, 4 biotypes of Monochoria korsakowii were collected. Pot experiments and enzyme assay were employed to detect the resistance. Pot experiments showed that the GR₅₀ (herbicide dose required for 50% reduction of shoot dry weight) of Liuhe resistant (R) and susceptible (S) biotypes to bensulfuron-metyl were 91.81 and 7.76 g/hm², respectively, with resistance index (RI) 13.6. Meanwhile, the GR₅₀ for Dehui R and S biotypes were 50.46 and 8.41 g/hm, respectively, with RI 6.0. In vitro, the IC₅₀ (herbicide concentration required for 50% inhibition) of ALS specific activity in Liuhe R and S biotypes to bensulfuron-methyl were 15036.3 and 237.2 nmol/L, respectively, with RI 63.4. The IC₅₀ for Dehui R and S biotypes were 10 756.2 and 396.8 nmol/L, respectively, with RI 27.1. The results indicated that the M. korsakowii in Liuhe and Dehui had evaluated resistance to bensulfuron-methyl and the decreased ALS sensitivity was one of causes for the resistance of M. korsakowii to the herbicide..

Wu MingGen ; Cao FengQiu ; Liu LiAng. 2007. Effect of sulfonylurea herbicides on the acetolactate synthases activity between resistant and susceptive biotypes of Monochoria korsakowii. Acta Phytophylacica Sinica 34 : 545 - 548.

The resistant biotype of Monochoria korsakowii Regel et Maack to sulfonylurea(SU) has been found in the paddy fields of Yanbian Region since 2004. In order to study its mechanism of the herbicide-resistance, analytical method of in vitro was employed to evaluate the inhibitory effect of SU on the acetolactate synthases (ALS) in Monochoria korsakowii. The test results indicated that the I₅₀ (herbicide concentrations required for 50% inhibition) of ALS specific activity to bensulfuron-methyl in resistant biotypes and susceptible biotype was 253.44×10^-7 mol/L and 2.80×10^-7 mol/L respectively, I₅₀ of ALS specific activity to pyruzasulfuron-ethyl in resistant biotypes and susceptible biotype was 1 802.15×10^-7 mol/L and 20.85×10^-7 mol/L respectively. The resistance ratio of resistance biotype to bensulfuron-methyl was 90.6 and to pyruzasulfuron-ethyl was 86.5. There is cross resistance between bensulfuron-methyl and pyruzasulfuron-ethyl. It suggested that the ALS of SU-resistance biotype was dulled to SU herbicides..

Wang GuangXi ; Watanabe, H. ; Uchino, A. ; Li Wei ; Itoh, K.. 2003. Estimation of out-crossing rate in Monochoria korsakowii using the herbicide resistance trait as a marker. Journal of Pesticide Science 28 : 429 - 430.

In order to discuss the rate of dispersion of the resistance gene of Monochoria korsakowii, we quantitatively estimated the out-crossing rates using the herbicide resistance trait as a marker on experimental populations. Two insect species, Apis mellifera and Xylocopa circumvolans, were observed on the flowers and the estimated out-crossing rates ranged from 10.4 to 67.8% with an average of 36.2%. The finding indicates that the trait can be transmitted via pollen by bees and expressed in hybrid offspring and further implies that the subsequent spread of resistance can occur through pollen migration. Thus, the evolution of resistance will be rapid..

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