• The Plant Pathology Journal
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• v.35 no.1
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• pp.51-62
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• 2019

A great variable response was observed when PP-3 and PP-J encumbered with 116 populations of root knot nematode (RKN) at two different temperatures ($25{\pm}2^{\circ}C$ and $30{\pm}2^{\circ}C$) and concentrations ($10^4$ and $10^5$ spores/ml). The PCR reaction amplified intergenic region between cytochrome oxidase subunit II gene (COII) and large subunit of rRNA gene (lrRNA) of the mitochondrial genome of different RKN species. The primer C2F3 and 1108 identified M. incognita with the highest frequency (52.6%) followed by M. javanica (36.8%) and M. arenaria (10.5%). The sizes of PCR products were 1.7 kb for M. incognita and M. javanica populations while populations of M. arenaria produced 1.1 kb fragment. The digestion with Hinf I yielded three different fragment length patterns on 1.5 % agarose gel. From current research it is concluded that intra-Meloidogyne genetic variability exist in RKN populations which have better encumbrance with P. penetrans.

• The Plant Pathology Journal
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• v.35 no.6
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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.

• Journal of Applied Biological Chemistry
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• v.56 no.4
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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.

• Journal of Plant Biotechnology
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• v.50
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• pp.163-168
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• 2023

Sweetpotato (Ipomoea batatas [L.]) is a globally important root crop cultivated for food and industrial processes. The crop is susceptible to the root-knot nematode (RKN) Meloidogyne incognita, a major plant-parasitic RKN that reduces the yield and quality of sweetpotato. Previous transcriptomic and proteomic analyses identified several genes that displayed differential expression patterns in susceptible and resistant cultivars in response to M. incognita infection. Among these, several sporamin genes were identified for RKN resilience. Sporamin is a storage protein primarily found in sweetpotato and morning glory (Ipomoea nil). In this study, transcriptional analysis was employed to investigate the role of sporamin genes in the defense response of sweetpotato against RKN infection in three susceptible and three resistant cultivars. Twenty-three sporamin genes were identified in sweetpotato and classified as group A or group B sporamin genes based on comparisons with characterized sweetpotato and Japanese morning glory sporamins. Two group A sporamin genes showed significantly elevated levels of expression in resistant but not in susceptible cultivars. These results suggest that the elevated expression of specific sporamin genes may play a crucial role in protecting sweetpotato roots from RKN infection.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.596-606
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• 2021

Soil-borne diseases are the major problems in mono cropping. A mixture (designated LTM-m) composed of agricultural wastes and a beneficial microorganism Streptomyces saraceticus SS31 was used as soil amendments to evaluate its efficacy for managing Rhizoctonia solani and root knot nematode (Meloidogyne incognita). In vitro antagonistic assays revealed that SS31 spore suspensions and culture broths effectively suppressed the growth of R. solani, reduced nematode egg hatching, and increased juvenile mortality. Assays using two Petri dishes revealed that LTM-m produced volatile compounds to inhibit the growth of R. solani and cause mortality to the root knot nematode eggs and juveniles. Pot and greenhouse tests showed that application of 0.08% LTM-m could achieve a great reduction of both diseases and significantly increase plant fresh weight. Greenhouse trials revealed that application of LTM-m could change soil properties, including soil pH value, electric conductivity, and soil organic matter. Our results indicate that application of LTM-m bio-organic amendments could effectively manage soil-borne pathogens.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.250-254
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• 2007

Bacillus thringiensis strain 108 was isolated from soil and had nematicidal activity against second stage juvenile of plant root-knot nematode, Meloidogyne incognita. The strain 108, a rod shape, spore forming and Gram positive bacterium, produced lecithinase, catalase, and ${\delta}$-endotoxin. The strain 108 belongs to H serotype 3, Bacillus thuringiensis var. kurstaki. A nematicidal substance of the strain 108 was partially purified on Sephadex G-25 gel filtration, activated carbon adsorption, silica gel adsorption, and Sephadex G-10 gel filtration. $LC_{90}$ of the partially purified substance against M incognita was $1.2\;{\mu}g/ml$. The nematicidal substance was stable by heat treatment at $100^{\circ}C$ for 1hr, but was perfectly lost nematicidal activity after autoclave ($110^{\circ}C$, 30 min).

• The Plant Pathology Journal
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• v.40 no.3
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• pp.261-271
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• 2024

Sulfur is one of the inorganic elements used by plants to develop and produce phytoalexin to resist certain diseases. This study reported a method for preparing a material for plant disease resistance. Sulfur nanoparticles (SNPs) stabilized in the chitosan-Cu²⁺ (CS-Cu²⁺) complex were synthesized by hydrolysis of Na₂S₂O₃ in an acidic medium. The obtained SNPs/CS-Cu²⁺ complex consisting of 0.32% S, 4% CS, and 0.7% Cu (w/v), contained SNPs with an average size of ~28 nm as measured by transmission electron microscopy images. The X-ray diffraction pattern of the SNPs/CS-Cu²⁺ complex showed that SNPs had orthorhombic crystal structures. Interaction between SNPs and the CS-Cu²⁺ complex was also investigated by ultraviolet-visible. Results in vitro nematicidal effect of materials against Meloidogyne incognita showed that SNPs/CS-Cu²⁺ complex was more effective in killing second-stage juveniles (J2) nematodes and inhibiting egg hatching than that of CS and CS-Cu²⁺ complex. The values of LC₅₀ in killing J2 nematodes and EC₅₀ in inhibiting egg hatching of SNPs/CS-Cu²⁺ complex were 75 and 51 mg/l, respectively. These values were lower than those of CS and the CS-Cu²⁺ complex. The test results on the nematicidal effect against M. incognita on coffee pots showed that the SNPs/CS-Cu²⁺ complex was 100% effective at a concentration of 150 mg/l. Therefore, the SNPs/CS-Cu²⁺ complex could be considered as a biochemical material with potential for agricultural applications to control root-knot nematodes.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1383-1391
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• 2016

The fungal strain EML-DML3PNa1 isolated from leaf of white dogwood (Cornus alba L.) showed strong nematicidal activity with juvenile mortality of 87.6% at a concentration of 20% fermentation broth filtrate at 3 days after treatment. The active fungal strain was identified as Aspergillus oryzae, which belongs to section Flavi, based on the morphological characteristics and sequence analysis of the ITS rDNA, calmodulin (CaM), and β-tubulin (BenA) genes. The strain reduced the pH value to 5.62 after 7 days of incubation. Organic acid analysis revealed the presence of citric acid (515.0 mg/kg), malic acid (506.6 mg/kg), and fumaric acid (21.7 mg/kg). The three organic acids showed moderate nematicidal activities, but the mixture of citric acid, malic acid, and fumaric acid did not exhibit the full nematicidal activity of the culture filtrate of EML- DML3PNa1. Bioassay-guided fractionation coupled with ¹H- and ¹³C-NMR and EI-MS analyses led to identification of kojic acid as the major nematicidal metabolite. Kojic acid exhibited dose-dependent mortality and inhibited the hatchability of M. incognita, showing EC₅₀ values of 195.2 μg/ml and 238.3 μg/ml, respectively, at 72 h post-exposure. These results suggest that A. oryzae EML-DML3PNa1 and kojic acid have potential as a biological control agent against M. incognita.

• Korean Journal of Medicinal Crop Science
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• v.12 no.5
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• pp.355-359
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• 2004

A survey was conducted during $April{\sim}May$ 2004 to determine the occurrence and population density of plant-parasitic nematodes in ginseng (Panax ginseng C.A. Meyer) growing fields, in major ginseng growing regions of Chungbuk, Chungnam, Gyeongbuk and Kyongki provinces. The survey revealed presence of eleven species of plant-parasitic nematodes namely, Criconemoides morgensis, Ditylenchus destructor, Helicotylenchus dihystera, Meloidogyne incognita, M. hapla, Paratylencgus lepidus, Pratylenchus penetrans, Psilenchus hilarulus, Trichodorus similis, Tylenchorhynchus claytoni and Xiphinema americanum. Frequency and density of each species were highly variable. M. incognita and M. hapla were the predominant species, their infestation observed in 46.3 and 39.4% fields with an average density of $78{\sim}254\;and\;76{\sim}211$ nematodes per $300\;cm^3$ soil, respectively. Whereas, T. similis and X. americanum were rarely observed; only in 2.3 and 1.8% of surveyed fields and their density was $10{\sim}17\;and\;7{\sim}10$ individuals per $300\;cm^3$ soil, respectively. They are recorded herewith for the first time from ginseng fields of Korea. In nematode-infestated fields, stunted plant growth with chlorotic leaves, and wilted plants were observed in patches.

• Research in Plant Disease
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• v.14 no.2
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• pp.117-121
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• 2008

To determine the economic threshold level of Meloidogyne incognita on cucumber in greenhouse conditions, cucumber seedlings(Cucumis sativa L. cv. 'Super Manchon') grafted on 'Jangsushintozoa'(Cucurbita maxima x Cu. moschata) were planted in wooden boxes($30{\times}40{\times}15cm,\;L{\times}W{\times}D$) under a plastic house in August 01 and harvested from Sep. 01-Oct. 30, 2006. The initial nematode population densities(Pi) in the wooden boxes were adjusted to 0, 10, 30, 100, 300, and 600 second-stage juveniles(J2)/100 $cm^3$ soil. The relationship of total fruit yield to Pi level could be adequately described by a linear regression equation, $Y=0.82-0.04{\cdot}Log_{10}$(Pi+1). Initial nematode densities(Pi) before planting in excess of 5 J2/1,000 $cm^3$ soil caused in total yields loss that is equivalent to the costs of granular nematicide application; Pi level in excess of 25 J2/1,000 $cm^3$ soil caused in total yields loss that exceed the costs for application of fumigants at current control costs. We propose two different management strategies depending on nematode densities, (i) application of non-fumigant granular nematicides for M. incognita Pi level of 5 J2/1,000 $cm^3$ soil and (ii) fumigant treatment with Pi level over 25 J2/1,000 $cm^3$ soil. Soil samples to determine population density of Meloidogyne spp. for advisory purposes should be taken several months before planting time, which allows a period of time enough for implementing management procedures.