• Korean Journal of Microbiology
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• v.27 no.3
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• pp.285-290
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• 1989

The biololgical effect of the preemergence rice field herbicide, butachlor(commercial name, Machete) on purple nonsulfur photosynthetic bacterium Rhodospirillum rubrum KS-301 has been studied under cultural conditions. Bacterial growth showed a tendency to decline according to the degree of the concentration of butachlor until $10^{-3}$ M and slmost stopped at $10^{-2}$M. The growth inhibitory action at $10^{-3}$M of butachlor was evident (4.2-18.7% inhibition of growth rate) but had little effect in nitrogen fixation. Conversely, there was a little enhancement effect(1%) in pyruvate, dinitrogen gas growing cultures. At concentration of $10^{-3}$ M, instead of spiral form, rod shapes were observed through phase contrast microscope and instead of vesicular intracytoplasmic membrane, irregular tubular forms were observed through electron microscope. Alkaline pH value slightly reversed tha inhibitory action of butachlor.

• Korean Journal of Weed Science
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• v.10 no.3
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• pp.227-232
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• 1990

The effects of alachlor [2-chloro-2', 6' diethyl-N-(methoxymethyl) acetanilide] treatment on nucleic acid, amino acid and protein synthesis were studied. The amide herbicide alachlor blocks the biosynthesis of the amino acids isoleucine, valine and aromatic amino acid in oat root tips. Nucleic acid was inhibited, but was not proportional to reduction in protein synthesis. $1{\times}10^{-4}M$ of alachlor treatment of oat roots inhibited 36% DNA synthesis, but DNA synthesis was not inhibited at $1{\times}10^{-5}M$. RNA synthesis was inhibited by $1{\times}10^{-5}M$ and $1{\times}10^{-4}M$ of alachlor 16 and 27%, respectively, while inhibition of protein synthesis did occur at same concentrations. Inhibition of protein synthesis also did not occur at concentration below $1{\times}10^{-4}M$ alachlor. It suggest that inhibition of protein sythesis caused significantly by alachlor($1{\times}l0^{-3}M$) result from secondary action.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.197-204
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• 1998

This study was conducted to determine the activity of ALS, content of endogenous free amino acids and fatty acids affected by herbicide mixture of cyhalofop-butyl, pyribenzoxim and pyrazosulfuron-ethyl. $I_{50}$ values (concentration required for 50% inhibition of ALS activity) of pyribenzoxim herbicide on the activity of ALS in Echinochloa crus-galli and Cyperus serotinus in vitro were recorded at 4${\times}$100 nM and 5${\times}$10 nM, respectively, while $I_{50}$ values of pyrazosulfuron against E crus-galli and C. serotinus were 4.5${\times}$10 nM and 4${\times}$10 nM, respectively, and the mixture of two herbicides showed additive effect on ALS activity at the low application rate, and independent effect at the high application rates of two herbicides. The inhibition rates of the three herbicides mixture treatment on the three branch-chain amino acids such as valine, leucine and isoleucine were 74.6%, 66.6% and 57.9% in C. serotinus and 36.6% 51.1% and 48.1% in E. crus-galli, respectively. A little bit higher inhibitory effect on the three branch-chain amino acids in C. serotinus and E. crus-galli seedlings was observed in two herbicide mixture of pyribenzoxim with pyrazosulfuron than three herbicide mixture of cyhalofop with pyribenzoxim and pyrazosulfuron. The interaction among three herbicides showed non-antagonism on the amounts of endogenous free amino acids.

• Journal of Applied Biological Chemistry
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• v.59 no.2
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• pp.159-164
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• 2016

Plant growth regulator is an essential pesticide to date while the available active ingredient is not well understood unlike fungicide, insecticide and herbicide. This study was aimed to evaluate a new chemical class of plant growth regulator, and the total of 92 benzene derivatives were screened for their germination and early stage of the root growth regulation on Brassica campestris. Thirty benzaldehydes, nine acids, one amide, and one ester showed potent root growth inhibitory activity (>70 % inhibition) while only salicylaldehyde showed potent germination inhibition ($IC_{50}=81.2mg/L$) suggesting that benzaldehyde was a key module candidate for the growth inhibition. Benzaldehydes were further evaluated for root growth inhibition. 2,3-Dihydroxybenzaldehyde and salicylaldehyde showed $IC_{50}$ values of 8.0 and 83.9 mg/L, respectively. On the other hand, salicylaldehyde, and 2,4,5-trihydroxybenzaldehyde were found to have root growth promotion effects less than 10 mg/L. This result suggests that the benzaldehyde is a new class candidate for plant growth regulator.

• Proceedings of the Ginseng society Conference
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• 1990.06a
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• pp.149-154
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• 1990

Various rates of 2, 4-2 were sprayed on 2 and 3 year old ginseng plants as fouler spray to define the critical concentration. No apparent plant injury was noticeable for those ginseng plants when application concentration of 2, 4-D doubled the recommended dosage (70 mil 10a). Neither abnormal fouler change occurred nor any inhibition in leaf and stem growth was resulted for the plants treated with 2, 4-D concentrated two times of the recommended dosage. When the rates of 2, 4-D application were increased greater than this level, injury ratings increased linearly with the rates of 2, 4-D application and plant growth was inhibited. Ethylene gas was not produced from the ginseng plant treated with 2 times concentrated 2, 4-D, how- ever the ginseng plants produced 0.03 to 0.09 ppd ethylene gas when the rate of application were increased 3 and 4 times, respectively. On the other hand the soybean treated with the recommended amount of 2i-D produced ethylene gas of 10-20 times higher compared with ginseng plants and died. Photosynthesis ability of the ginseng leaf was significantly decreased by 2, 4.D fouler application but it was recovered 4 weeks after 2, 4-D fouler treatment. The herbicide 2, 4-D was appreciated to 2, 3 and 4 years old ginseng plants as fouler spray with the rates of 0.5, 1.0, 1.5 and 2.0 times of the recommended dosage to define the effects of 2, 4-D on the plant growth and root yield of the ginseng, There were no significant differences in the leaf and stem growth between untreated and 2, 4-D treated plant. Berry maturing of 3 and 4 year old ginseng was not influenced by 2, 4-D. The root weight of 4 years old ginseng plant was not reduced b). application of 2, 4-D concentrated 2 times of the recommended dosage. Application time of the herbicide 2, 4-D had no effects on the leaf or stem growth of 2, 3 and 4 year old year old ginseng plants. When the ginseng seedling was treated with 2, 4-D, detrimental phenomena as stem bending and deceleration of seedling leaf margin occurred, but stem bending was recovere d in a few day.

• Journal of Bio-Environment Control
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• v.15 no.3
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• pp.277-282
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• 2006

For searching the natural herbicide-components, the seed germination and seedling growth of receptor plant species (Brassica campestris, Sesamum indicum, Perilla frutescens and Echinochloa crus-galli) were investigated in four solvent-extracts extracted from Coptis chinensis Franch. The seed germination of receptor plant species was largely inhibited in 2,000 ppm of ethyl acetate compared to the control, and it was inhibited in order of P. frutescens, B. campestris, E. crux-galli, and S. indicum. In seedling growth, the shoot and root elongations of receptor plant species were inhibited in order of S. indicum, P. frutescens, B. campostris, and E. crus-galli. Root elongation was remarkably reduced in order of $H_2O$, butyl alcohol, and hexane, ethyl acetate extracts. Of four receptor plant species, seed germination and seedling growth of B. campestris and S. indicum showed the species-specific reaction to the solvent-extracts extracted from C. chinemis. $H_2O$ extract had a natural herbicide potential to the seed germination or root elongation in B. campestris and S. indicum. The result can be provided a basic data f3r the development of natural herbicide.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.155-163
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• 1985

Three pyrazole-herbicides, pyrazolate, pyrazoxyfene and benzophenap, were evaluated for their interaction in controlling barnyardgrass (Echinochloa crusgalli) with two chloroacetamide-herbicides, butachlor and pretilachlor. Percent inhibition of barnyardgrass growth by pyrazolate, pyrazoxyfene, and benzophenap was 44%, 64%, and 0%, respectively, when each was applied at the 1.5 leaf-stage of barnyardgrass at a rate of 3㎏ ai per ㏊ as single treatment, and the benzophenap showed 60% inhibition when it was applied at the coleoptile stage. While the lowest rate controlling the 1.5 leaf-stage barnyardgrasses by 98 to 100% of the butachlor and pretilachlor was 1.5㎏ and 200g per ㏊, respectively. All of the combinations of pyrazolate with butachlor, pyrazoxyfene with pretilachlor, and benzophenap with butachlor have shown synergistic interaction in controlling barnyardgrass on the Chisaka's isobole of 90% growth inhibition as well as on the Colby`s interaction efficacy data; synergism indices were 2.44, 1.62 and 1.52 in order. The dose combinations shown the maximal synergism were 1870g of pyrazolate with 140g of butachlor (1:0.075), 33008 of pyrazoxyfene with 338 of pretilachlor (1:0.01), and 3350g of benzophenap with 520g of butachlor (1:0.15) on the ai/㏊ basis.

• Korean Journal of Weed Science
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• v.11 no.2
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• pp.137-141
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• 1991

This study was conducted to determine the response of newly developed chlorophyllous cells against photosynthesis inhibitory herbicides in LS medium. Inhibition of the growth of the selected chlorophyllous cells in the LS medium containing sucrose 1%, NAA $10^{-5}$ M and BA $10^{-6}$ M under light condition increased as the concentrations of paraquat increased from $10^{-6}$ M to $10^{-4}$ M. The calli died in $10^{-4}$ M paraquat treatment and the inhibition of calli growth was greater when $CO_2$ was supplied. In the treatment of herbicide diuron, the inhibition of calli growth also increased as the concentrations of diuron increased from $10^{-6}$ M to $10^{-3}$ M and more inhibition was observed at 1% sucrose than 2% sucrose.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.1-11
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• 2001

New technologies will have a large impact on the discovery of new herbicide site of action. Genomics, combinatorial chemistry, and bioinformatics help take advantage of serendipity through tile sequencing of huge numbers of genes or the synthesis of large numbers of chemical compounds. There are approximately $10^{30}\;to\;10^{50}$ possible molecules in molecular space of which only a fraction have been synthesized. Combining this potential with having access to 50,000 plant genes in the future elevates tile probability of discovering flew herbicidal site of actions. If 0.1, 1.0 or 10% of total genes in a typical plant are valid for herbicide target, a plant with 50,000 genes would provide about 50, 500, and 5,000 targets, respectively. However, only 11 herbicide targets have been identified and commercialized. The successful design of novel herbicides depends on careful consideration of a number of factors including target enzyme selections and validations, inhibitor designs, and the metabolic fates. Biochemical information can be used to identify enzymes which produce lethal phenotypes. The identification of a lethal target site is an important step to this approach. An examination of the characteristics of known targets provides of crucial insight as to the definition of a lethal target. Recently, antisense RNA suppression of an enzyme translation has been used to determine the genes required for toxicity and offers a strategy for identifying lethal target sites. After the identification of a lethal target, detailed knowledge such as the enzyme kinetics and the protein structure may be used to design potent inhibitors. Various types of inhibitors may be designed for a given enzyme. Strategies for the selection of new enzyme targets giving the desired physiological response upon partial inhibition include identification of chemical leads, lethal mutants and the use of antisense technology. Enzyme inhibitors having agrochemical utility can be categorized into six major groups: ground-state analogues, group specific reagents, affinity labels, suicide substrates, reaction intermediate analogues, and extraneous site inhibitors. In this review, examples of each category, and their advantages and disadvantages, will be discussed. The target identification and construction of a potent inhibitor, in itself, may not lead to develop an effective herbicide. The desired in vivo activity, uptake and translocation, and metabolism of the inhibitor should be studied in detail to assess the full potential of the target. Strategies for delivery of the compound to the target enzyme and avoidance of premature detoxification may include a proherbicidal approach, especially when inhibitors are highly charged or when selective detoxification or activation can be exploited. Utilization of differences in detoxification or activation between weeds and crops may lead to enhance selectivity. Without a full appreciation of each of these facets of herbicide design, the chances for success with the target or enzyme-driven approach are reduced.

• Korean Journal of Weed Science
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• v.15 no.1
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• pp.54-62
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• 1995

Acetolactate synthase activity inhibition and herbicidal activities were investigated with 2 sulfonylureas [chlorsulfuron{2-chloro-N-{{(4-methoxy-6-methyl-1,3,5-triazin-2-yl) amino} carboxyl} benzenesulfonamide}, metsulfuron-methyl{methyl-2{{{{(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino}carbonyl}amino}sulfonyl}benzoic acid}, and 2 imidazoli-nones [imazethapyr{2-{4,5-dihydro-4-methyl-4-(1-methyl)-5-oxo-1H-imidazol-2-yl}-5-ethyl-3-pyridinecarboxylicacid}, imazaquin{2-{4,5-dihydro-4-methyl-4-(1-methyl)-5-oxo-1H-imidazol-2-yl}-3-quinoline carboxylic acid} herbicides. A broad weeding spectrum was observed with the treated herbicides at low application rates. Both corn(Zea mays L.) and sorghum(Sorghum bicolor Moench) were very sensitive to the two herbicide groups. Although legumes, such as soybean(Glycine max Merr.), clover(Trifolium repense L.), and indian jointvetch(Aeschnomene indica L.) were sensitive to the sulfonylureas, they were tolerant to the imidazolinones. On the contrary, wheat(Triticum aestivum L.) and barley(Hoderum sativum Jess.) showed the reverse responses of the legumes to the two herbicide groups. Quackgrass(Agropyron repens(L.) P. Beauv.). however, was commonly tolerant to the two herbicide groups. Degrees of crop injury and acetolactate synthase inhibition also varied with the crops examined. The 50% inhibition concentrations of sulfonylureas on acetolactate synthase in vitro activity($IC_{50}$) from corn, wheat, and soybean did not relate to the greenhouse herbicidal activities ($GI_{50}$). With chlorsulfuron, for example, wheat had more than 100 times higher $GI_{50}$ than corn and soybean, but the $IC_{50}$ was 4 to 10 times lower. Similar observation was made with metsulfuron-methyl. However, closer relationships between $IC_{50}$ and $GI_{50}$ were found with the imidazolinones. When imazethapyr was applied, the order of $GI_{50}$ values against com, wheat, and soybean was the same as that of $IC_{50}$.