Mechanisms of glyphosate-resistant horseweed (Conyza canadensis) collected from tangerine orchards in Korea

보보,WeiQiang Jia,Thi Hien Le,원옥재,Botir Khaitov,조광민,박인곤,박기웅 한국원예학회 2021 Horticulture, Environment, and Biotechnology Vol.62 No.6

Chemical control has become less eff ective for the invasive weed species horseweed ( Conyza canadensis ) found in tangerine( Citrus reticulate ) orchards of Korea. The dose–response assays of the biotypes of C. canadensis collected in 2017 fromthe Jeju province of Korea demonstrated that the amount of glyphosate needed for 50% growth reduction (GR 50 ) in theglyphosate-resistant (GR) biotype was up to 100 times greater than that in the glyphosate-susceptible (GS) biotype (0.328 kga.e. ha −1 ). However, the mechanism of resistance in the GR populations of C. canadensis in Korea is unknown. Therefore,this study aimed to determine the mechanism of resistance to glyphosate in the Korean C. canadensis populations. Shikimicacid accumulation and 5 -enolpyruvyl shikimate- 3 -phosphate synthase ( EPSPS ) gene expression were analyzed in a GR anda GS biotype of C. canadensis. The GR biotype showed less shikimic acid accumulation than the GS biotype. A target pointmutation in the sequence encoding the Pro 106 of EPSPS1 was not found after sequencing the GR biotype. Moreover, theexpression level of EPSPS1 was not altered signifi cantly following application of glyphosate to the GS and GR biotypes,whereas the levels of M10 and M11 ABC transporter genes which play an important role in plant growth and nutrition,and the interaction of the plant with its environment were found to be slightly higher in the glyphosate-treated GS and GRbiotypes than the untreated control plants. Our results show that M10 and M11 are likely to be involved in the glyphosateresistance mechanism in C. canadensis . Consequently, non-chemical control methods should be implemented to manage orslow the spread of glyphosate resistance in C. canadensis.

Glyphosate Resistant Conyza canadensis Occurring in Tangerine Orchards of Jeju Province of Korea

보보,원옥재,노석원,박기웅,박인곤 한국잔디학회 2017 Weed & Turfgrass Science Vol.6 No.4

Conyza canadensis is the weed species which most frequently develops resistance to glyphosate in many agricultural crop fields. The continuous use of glyphosate has resulted in the spontaneous occurrences of resistant biotypes. This research was conducted to investigate the response of suspected C. canadensis biotypes to glyphosate. Seeds of C. canadensis were collected from 18 sites in tangerine orchards in Jeju province of Korea. In the preliminary screening, 6 resistant and 12 susceptible biotypes were found at the recommended glyphosate rate (3.28 kg a.i. ha-1). The susceptible biotypes were completely killed at the field application rate whereas the resistant biotypes were initially injured but recovered 14 days after glyphosate application. This is the first case of glyphosate resistance found in Korea despite the national ban on genetically modified glyphosate tolerant crops cultivation. Extended monitoring should be conducted to understand how widely spread the glyphosate resistant C. canadensis is and to estimate the severity of this weed problem in the tangerine orchards of Korea.

Current status and agronomic aspects of herbicide resistance in Korea

보보,정인호,원옥재,WeiQiang Jia,윤혜진,Botir Khaitov,Thi Hien Le,Mirjalol Umurzokov,Farrukh Ruziev,임민주,조광민,박기웅,이증주 충남대학교 농업과학연구소 2019 Korean Journal of Agricultural Science Vol.46 No.2

Weeds are a serious problem in crop production. Use of synthetic herbicides is rapidly increasing in weed management worldwide including Korea. Herbicide application reduces the time spent on weed control. However, the evolution of resistance to herbicides in weeds has become widespread as a natural response to selection pressure imposed by agricultural management activities. If an herbicide with the same mechanisms of action is used repeatedly and intensively, it can rapidly select for a weed biotype that shifts toward difficult-to-control becoming a more tolerant weed and lead to the evolution of herbicide-resistant weeds. Moreover, agricultural and biological factors have an important role in the development of herbicide-resistant weed populations. Mitigating the evolution of herbicide resistance in weeds relies on reducing selection through the diversification of weed control techniques. The resistance management of weeds in the future will strongly depend on intensive cropping systems. The current situation of intensive cropping systems with their heavy reliance on the efficacy of chemical weed control will not lead to significant containment of this problem. Therefore, management strategies need to overcome the further spread of herbicide resistance in weeds in Korean crop production. This review presents the current information on herbicide resistance in Korea and factors controlling the development of herbicide resistant weeds.

Alternative Herbicides to Manage Unintentionally Released Transgenic Canola

Mirjalol Umurzokov,정인호,Farrukh Ruziev,보보,WeiQiang Jia,레티현,Botir Khaitov,조광민,김윤하,이훈복,조진웅,손수인,박기웅 한국잔디학회 2019 Weed & Turfgrass Science Vol.8 No.2

One of the main concern of transgenic crops is unintentional release of unwanted gene or genes through pollen-mediated gene flow. Since 2009, transgenic canola (Brassica napus) contained herbicide resistant gene is being unintentionally released into the Korean ecosystem. This study was conducted to identify alternative herbicides to eliminate transgenic canola under greenhouse and field conditions in 2018 and 2019, Daejeon South Korea. Four pre- and five post-emergence herbicides were used at 1x and 2x recommended rates as a chemical treatment. The growth parameters of the trial plant and control efficacy of the herbicides determined separately according to the application method (pre and post) and experimental condition (greenhouse and field). Except glufosinate-ammonium, all the post-emergent herbicides including bentazone, fluthiacet-methyl, MCPA and bentazone sodium had almost 100% canola control efficacy at both 1x and 2x recommended rates. Regarding the pre-emergence herbicides, dichlobenil and oxyfluorfen showed a full control efficacy at both 1x and 2x recommended rates. It is worth noted that when linuron was applied, although some of the seeds were germinated, a gradual death was observed. While, s-metolachlor was not suggested to manage the canola as a chemical control because of its very low efficacy on this plant.

Growth Response of Weed Species in a Paddy Field under Elevated Temperatures

Md. Shahidul Haque Bir,레티현,원옥재,보보,Farrukh Ruziev,Mirjalol Umurzokov,WeiQiang Jia,윤혜진,Botir Khaitov,박기웅 한국잔디학회 2018 Weed & Turfgrass Science Vol.7 No.4

The present study aimed to investigate the growth response of rice and paddy weeds under varying temperatures created artificially in the phytotron under field condition. Rice ( Oryza sativa L .), three annual ( Ludwigia prostrata, Monochoria vaginalis, and Echinochloa oryzicola ) and three perennial ( Scirpus planiculmis, Eleocharis kuroguwai , and Sagittaria sagittifolia ) paddy weeds were grown under different temperature regimes (ambient, ambient+0.8°C, ambient+1.9°C, and ambient+3.4°C). It was observed that the growth of both rice and paddy weed species increased with the elevation of temperature. However, the growth of weeds was much greater than that of rice under elevated temperature. The shoot dry weight of rice was 8.9%, 13.1%, and 30.4% greater at the ambient+0.8, +1.9 and +3.4℃, respectively compared to the ambient temperature. Among the paddy weed species, L. prostrate exhibited the most significant increased level of both dry weight and leaf area presenting 211.8% and 214.3% higher, respectively at the ambient+3.4℃ than that of the ambient temperature. Growth of E. oryzicola and M. vaginalis were slightly higher compared to the growth of rice under elevated temperature. The growth of perennial weed species of S. sagittifolia exhibited 124.8% higher dry weight at the ambient+3.4℃ than at the ambient. Our findings suggest that elevation temperatures might provide an even greater competitive advantage to weeds with concomitant negative effects on rice production.