• The Plant Pathology Journal
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• 제34권1호
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• pp.35-43
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• 2018

Root-knot nematodes (Meloidogyne spp.) are parasites that attack many field crops and orchard trees, and affect both the quantity and quality of the products. A root-colonizing bacterium, Pseudomonas chlororaphis O6, possesses beneficial traits including strong nematicidal activity. To determine the molecular mechanisms involved in the nematicidal activity of P. chlororaphis O6, we constructed two mutants; one lacking hydrogen cyanide production, and a second lacking an insecticidal toxin, FitD. Root drenching with wild-type P. chlororaphis O6 cells caused juvenile mortality in vitro and in planta. Efficacy was not altered in the fitD mutant compared to the wild-type but was reduced in both bioassays for the mutant lacking hydrogen cyanide production. The reduced number of galls on tomato plants caused by the wild-type strain was comparable to that of a standard chemical nematicide. These findings suggest that hydrogen cyanide-producing root colonizers, such as P. chlororaphis O6, could be formulated as "green" nematicides that are compatible with many crops and offer agricultural sustainability.

• Journal of Microbiology and Biotechnology
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• 제30권5호
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• pp.700-707
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• 2020

The root-knot nematode (Meloidogyne incognita) is an important pathogen in crop cultivation, however, few methods are available to control this parasitic roundworm. In this study, the nematicidal effects of approximately 30 Streptomyces strains isolated from soil samples of Mt. Naejang (Korea) were tested against Meloidogyne incognita, and the culture broth of the strains KRA-24 and KRA-28 exhibited approximately 75% and 85% insecticidal activity, respectively, in in vitro assays. In in vivo pot experiments, these strains reduced the number of nematodes in the soil and the number of egg masses in the roots of red peppers. The two strains also survived in the presence of insecticidal agents (0.1 to 3.0%) such as fosthiazate, ethoprophos and terbufos when they were used in parallel. The mixture of KRA-24 or KRA-28 culture broth and fosthiazate exhibited nematicidal effects that were similar to those observed when KRA-24 or KRA-28 were used alone. Our results clearly suggest that the Streptomyces strains KRA-24 and KRA-28 should be promoted as a biocontrol agent against Meloidogyne incognita.

• 대한화학회지
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• 제57권2호
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• pp.221-226
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• 2013

A series of some novel 2-[5-(substituted phenyl)-[1,3,4]oxadiazol-2-yl]-benzoxazoles were synthesized by using benzoxazole-2-carboxylic acid on reaction with thionyl chloride in presence of ethanol solvent at room temperature gave benzoxazole-2-carbonyl chloride, which is turned into benzoxazole-2-carboxylic acid hydrazide on reaction with hydrazine hydrate in ethanol solvent under reflux. The subsequent treatment of benzoxazole-2-carboxylic acid hydrazide with an appropriate aromatic carboxylic acid in presence of polyphosparic acid under reflux afforded the title compounds. The chemical structures of the newly synthesized compounds were elucidated by their IR, $^1H$ NMR and Mass spectral data analysis. Further the compounds are used to find out their ability towards anti microbial and nematicidal activity.

• 한국토양비료학회지
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• 제44권2호
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• pp.228-235
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• 2011

친환경 선충 방제제 개발을 위해 경북 성주군 선남면 및 충남 공주시 우성면의 시설원예 재배지 토양으로 부터 선충 포식성이 뛰어난 곰팡이 Arthrobotrys thaumasia Nema-1과 선충 표피성분인 collagen과 알집 주성분인 gelatin 분해능이 뛰어난 Pseudomonas putida C-5를 분리 하였다. 이들 분리균의 선충치사 효과를 검토한 결과, A. thaumasia Nema-1 곰팡이 배양액 $5,000mL\;L^{-1}$을 처리 시 방제효과는 72시간 후에 55%이었으나, 포식성 곰팡이 Nema-1과 P. putida C-5 세균 배양액 각각 $5,000mL\;L^{-1}$ 혼합 처리구에서는 65%로 상승하였다. 또한 선충치사효과를 증진시키기 위하여 살선충 활성이 있다고 보고된 계피추출물 $50mg\;L^{-1}$을 $5,000mL\;L^{-1}$의 Nema-1과 C-5 배양액과 혼합하여 처리하였을 때 72시간 경과 후의 치사율은 89%로 상승되었으며, 대표적 살선충제인 선충탄(Fosthiazate) $50mg\;L^{-1}$의 방제가 17%와 님오일 $2,000mL\;L^{-1}$의 방제가 57% 보다 훨씬 높은 수준이었다. 이상의 결과는 생물학적 선충방제제는 미생물 또는 식물체 추출물 단제 보다는 혼합물 형태로 사용하는 것이 더 효과적이라는 결과를 제시하였다.

• 농약과학회지
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• 제8권4호
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• pp.353-357
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• 2004

국내 시설재배지에서 고구마뿌리혹선충(Meloidogyne incognita)의 발생으로 많은 경제적인 피해가 발생하고 있으나 이를 효과적으로 방제 할 수 있는 천연물 기원의 친환경 자재가 거의 없는 실정이다. 국내의 자생식물 중 뿌리혹선충에 활성이 있는 식물 종을 선발하기 위하여 자생식물 26과 43종으로 부터 메탄올 조추출물을 얻은 다음, 기주식물인 토마토 뿌리로부터 얻은 뿌리혹선충을 조추출물이 1,000 mg $kg^{-1}$수준으로 포함된 24-well tissue culture testplate에 $1\times10^2$ 마리 수준으로 처리하고, 해부현미경 하에서 살선충 효과를 검정하였다. 실험에 사용한 43종의 식물시료 중 쇠비름(Portulaca oleraceae L.)과 쇠별꽃(Stellaria aquatica SCOP.) 조추출물의 살선충 효과는 각각 00.0%되 40.6%이었다. 그러나 대부분의 식물시료 조추출물은 살선충 효과가 30% 미만으로 낮았다. 쇠비름과 쇠별 꽃 조추출물에 함유되어 있는 활성물질을 단리 할 경우 친환경농가에서 뿌리혹선충 예방 혹은 방제용도로 활용될 수 있을 것이라 사료된다.

• Journal of Applied Biological Chemistry
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• 제56권4호
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• pp.199-204
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• 2013

The nematicidal, antifungal and antioxidant activities of methanol extracts from six Vietnamese native medicinal plants were evaluated by various assays in vitro. Of the plant extracts tested, Terminalia nigrovenulosa was found to possess the highest activity when compared to the others. The leaves and bark of T. nigrovenulosa showed strong inhibitory activity against Meloidogyne incognita and Fusarium solani. The DPPH (1,1-Diphenyl-2-picryl-hydrazyl) radical scavenging, reducing power and total antioxidant activities of T. nigrovenulosa bark were higher than that of the remainder plant extracts. Chitinase activity of these plants was also investigated using SDS-PAGE. The results obtained in the present study indicate that T. nigrovenulosa leaf extracts are the greatest potential source as nematicides and fungicides for the control of M. incognita and F. solani. In particularly, T. nigrovenulosa bark extracts could be used as a potential source of commercially viable levels of natural antioxidant.

• The Plant Pathology Journal
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• 제35권6호
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• pp.662-673
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• 2019

Root-knot nematodes (RKNs) are among the most destructive plant-parasites worldwide, and RKN control has been attempted mainly using chemical nematicides. However, these chemical nematicides have negative effects on humans and the environment, thus necessitating the search for eco-friendly alternative RKN control methods. Here, we screened nematicidal lactic acid bacteria (LAB) isolated from kimchi and evaluated their efficacy as biocontrol agents against RKNs. Of 237 bacterial strains, Lactobacillus brevis WiKim0069 showed the strongest nematicidal activity against the second-stage juveniles (J2) of Meloidogyne incognita, M. arenaria, and M. hapla and inhibited the egg hatch of M. incognita. The culture filtrate of WiKim0069 had a pH of 4.2 and contained acetic acid (11,190 ㎍/ml), lactic acid (7,790 ㎍/ml), malic acid (470 ㎍/ml), and succinic acid (660 ㎍/ml). An artificial mixture of the four organic acids produced by WiKim0069 also induced 98% M. incognita J2 mortality at a concentration of 1.25%, indicating that its nematicidal activity was derived mainly from the four organic acids. Application of WiKim0069 culture filtrate suppressed the formation of galls and egg masses on tomato roots by M. incognita in a dose-dependent manner in a pot experiment. The fermentation broth of WiKim0069 also reduced gall formation on melon under field conditions, with a higher efficacy (62.8%) than that of fosthiazate (32.8%). This study is the first report to identify the effectiveness of kimchi LAB against RKNs and to demonstrate that the organic acids produced by LAB can be used for the RKN management.

• 식물병연구
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• 제21권2호
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• pp.50-57
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• 2015

효과적으로 선충 방제에 사용되던 토양훈증제 methyl bromide와 비훈중제 농약이 환경오염 문제로 인해 사용이 금지됨에 따라 선충의 방제는 어려워지고 있다. 따라서 이를 대체할 수 있는 생물 기반의 살선충제의 개발이 시급히 요구된다. 본 연구는 화학적 농약의 대안으로서 방선균을 이용한 살선충제 개발을 목적으로 2,700개의 토양방선균 배양액의 50% 메탄올 추출액의 뿌리혹선충에 대한 살선충 활성을 스크리닝하였다. AN110065 균주는 배양액 10%에 해당하는 50% 메탄올 추출액 20% 처리 1일 후 78.9%의 치사 활성을 보였으며, 처리 3일 후 94.1%의 살선충 활성을 보였다. 선발 균주의 분자생물학적 동정을 위해 16S rRNA sequencing 분석을 수행한 결과 S. netropsis와 99.78%의 상동성을 보였다. S. netropsis AN110065 배양액을 에틸 아세테이트, 부탄올을 이용하여 용매 분획하여 에틸 아세테이트와 부탄올, 물 추출물에 대한 살선충 활성을 조사한 결과 에틸 아세테이트 추출물의 $1000{\mu}g/ml$농도에서 83.5%로서 가장 우수한 살선충 활성을 보였다. AN110065 배양액의 토마토작물에 대한 뿌리혹선충병 방제 활성을 조사한 결과 10배 희석액 처리구에서 눈에 띄게 뿌리혹형성을 저해하였다. 이와 같은 결과로 AN110065 균주는 유기농업에서 사용할 수 있는 미생물 제제로서의 가능성이 있음을 나타내었다.

• Journal of Applied Biological Chemistry
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• 제48권4호
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• pp.161-166
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• 2005

Among 24 isolates of fluorescent Pseudomonads, 5 isolates named as LPT1, LPT2, LPT3, LPT4 and LPT5 were screened in vitro for their nematicidal activity against cyst forming nematode, Heterodera cajani causing patchiness, poor and stunting growth besides discoloration in Sesamum indicum. Second stage juveniles of H. cajani hatched from egg masses were collected from roots of host plant and subjected to fresh and heat-treated culture filtrate of isolates for 24 h. Mortality of H. cajani was recorded on the basis of parameters used for test organism bioassay. Among these isolates, Pseudomonas aeruginosa LPT5 caused maximum mortality towards second stage juvenile of H. cajani in vitro. Five isolates were used as seed coating for the management of cyst forming nematode H. cajani on sesame in green house condition. The strains LPT5 was better than the other strains in reducing the population of H. cajani both in vitro and in vivo. The reduction in cyst and juveniles population was found to be 49 and 60%, respectively when seeds were coated with strain LPT5. Among other strains, LPT4 was also found to inhibit the cyst and juveniles population 12 and 36% respectively. Increases in early vegetative plant growth parameters recorded in both in vitro and in vivo further revealed the significance of indigenous bacteria in comparison to introduced strain.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.388-393
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• 2023

This study evaluated the in vitro nematicidal activity of Glycyrrhiza uralensis root extracts (GuRE) on Meloidogyne incognita eggs and juveniles. The results showed that treatment of M. incognita eggs with 2.0 mg/mL GuRE for 5 and 10 d resulted in 64.0 and 68.1% hatch inhibition, respectively. Furthermore, the relative mortality of J2 was 96.2% after treatment with 2.0 mg/mL GuRE for 48 h. Changes in the shape of the eggs and juveniles were determined after incubation with 2.0 mg/mL GuRE for 5 d and 48 h, respectively. These preliminary results suggest that GuRE can be used as an environment-friendly bio-nematicide to control root-knot nematodes. In the future, in vivo assays should be conducted using GuRE to ascertain its potential for widespread application as a nematicide.