• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.298-303
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• 1995

The biological control effect of Trichoderma harzianum on the Fusarium wilt of strawberry and several factors affecting on its efficacy were examined through pot experiments. T. harzianum grown on wheat barn, rice straw, rice hull, sawdust or barley straw was respectively incorporated into the pathogen-infected soil, and significantly suppressed the strawberry wilt caused by Fusarium oxysporum f. sp. fragariae. The wheat bran or rice straw culture of T. harzianum suppressed the disease incidence more effectively than other substrates for culture, decreasing it to 68% of the untreated control. The conidial suspension of T. harzianum alone or the suspension mixed with crab shell also effectively reduced the disease incidence. The control effectiveness of T. harzianum was high in acid soil (pH 3.5~5.5). In sandy loam soil, the disease incidences and population densities of the pathogen were decreased by the treatment of T. harzianum, while there was no significant effect of T. harzianum on the pathogen in loam soil.

• The Plant Pathology Journal
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• v.29 no.4
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• pp.446-450
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• 2013

The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.7-12
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• 2002

The intergenic spacer (IGS) region of the ribosomal DNA of species in Fusarium section Liseola was analyzed by amplification and subsequent digestion with several restriction enzymes. The length of the amplified IGS region was about 2.6 Kb in all strains except F.moniliforme 12 Which was about 2.9 Kb. The enzymes, EcoRI, HincII, SalI, HindIII, PstI and SmaI, digested the IGS region and nine haplotypes were identified among 11 strains. In the dendrogram based on PCR-RFLP of IGS region combined the results of section Liseola in this study and section Elegans in previous study, variation in the IGS appears to offer considerable potential to resolve intraspecific relationship as well as interspecies or intersection.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.403-409
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• 2022

In biological particles such as Fusarium species, ice nucleation activity (INA) has been observed. Fusarium strains isolated from apple declined trees in Korea were identified with a multilocus sequence analysis using the tef1 and rpb1 genes. Droplet-freezing and tube-freezing assays were used to determine the INA of the strains, using Pseudomonas syringae pv. syringae KACC 21200 as a positive control and resulting in seven INA+ fungal strains that were identified as F. tricinctum (KNUF-21-F17, KNUF-21-F18, KNUF-21-F29, KNUF-21-F32, KNUF-21-F38, KNUF-21-F43, and KNUF-21-F44). The effect of Fusarium INA+ KNUF-21-F29 was compared to that of INA- strains on Chrysanthemum morifolium cv. Shinma explants. A higher callus formation and no-shoot formation were observed, suggesting that fungal INA could play a role in cold injuries and be a factor to consider in rapid apple decline. To the best of our knowledge, this is the first report of INA fungal strains isolated in Korea.

• Journal of Food Hygiene and Safety
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• v.37 no.1
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• pp.9-14
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• 2022

The purpose of this study was to analyze the hazard of fungi in Garaetteok (Korean rice cake) by isolating and identifying of fungi contaminated with Garaetteok and investigating the possibility of mycotoxin production. Garaetteok used in this study were the ones that were returned back to the manufacturers in Jeollanam-do due to the presence of foreign matters presumed to be fungi. The fungi foreign matter was collected and inoculated on Potato dextrose agar, Malt extract agar, and Czapek yeast extract agar, and then cultured at 25℃ for 7 days. The micro-structure was observed under an optical microscope for the colonies in which pure isolation was confirmed. The gene sequencing of the product of amplified PCR was analyzed using the ITS primer. Colony-1 and 2 maintained the same properties in each tray, confirming that they were purely isolated. Budding cells were observed from the Colony-1, thus, it was determined to be yeast. Colony-2 was determined to be a fungus that belongs to Fusarium spp. as fusiform conidia were observed. As a result of gene sequencing, a total of 76 cases of fungi of Fusarium spp. were found, among which Fusarium solani was the most observed cases (53 cases). From the morphological and genetic identification, Colony-2 was identified as Fusarium spp., specifically, Fusarium solani. The fungi found in Fusarium spp. produce mycotoxins such as nivalenol, zearalenone, and fumonisin, which may cause vomiting, diarrhea, and cancer. Conclusively, the results confirm the possibility of mycotoxin production by Fusarium spp. isolated from Garaetteok. Consequently, when an unknown fungus was found, it is necessary to isolate and identify the fungus, determine whether it is a mycotoxin producing species, and strengthen relative administrative measures, accordingly.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.54-54
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• 2015

Crops lack genetic resistance to most necrotrophic soil-borne pathogens and parasitic nematodes that are ubiquitous in agroecosystems worldwide. To overcome this disadvantage, plants recruit and nurture specific group of antagonistic microorganisms from the soil microbiome to defend their roots against pathogens and other pests. The best example of this microbe-based defense of roots is observed in disease-suppressive soils in which the suppressiveness is induced by continuously growing crops that are susceptible to a pathogen. Suppressive soils occur globally yet the microbial basis of most is still poorly described. Fusarium wilt, caused by Fusarium oxysporum f. sp. fragariae is a major disease of strawberry and is naturally suppressed in Korean fields that have undergone continuous strawberry monoculture. Here we show that members of the genus Streptomyces are the specific bacterial components of the microbiome responsible for the suppressiveness that controls Fusarium wilt of strawberry. Furthermore, genome sequencing revealed that Streptomyces griseus, which produces a novel thiopetide antibiotic, is the principal species involved in the suppressiveness. Finally, chemical-genetic studies demonstrated that S. griseus antagonizes F. oxysporum by interfering with fungal cell wall synthesis. An attack by F. oxysporum initiates a defensive "cry for help" by strawberry root and the mustering of microbial defenses led by Streptomyces. These results provide a model for future studies to elucidate the basis of microbially-based defense systems and soil suppressiveness from the field to the molecular level.

• The Plant Pathology Journal
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• v.24 no.2
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• pp.112-117
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• 2008

Pre-infection behavior of Fusarium circinatum on stems of pine species was investigated with scanning electron microscopy. Two-year-old stems of Pinus densiflora and p. rigida were inoculated with the fungal conidial suspension and subjected to $25^{\circ}C$ for up to 16 hr. Most microconidia germinated 12 hr after inoculation on pine stems. Conidia produced germ tubes from either one or both ends of microconidia. Germ tubes grew over the stem surface and appeared to enter host tissues through natural openings on pine stems. Surface cracks in the cork were entrance sites of germ tubes of F. circinatum. In addition, host cell wall cracks were often found at the tip of germ tubes. The cuticle appeared to be eroded either at the tip of germ tubes or around germlings. Germ tubes also produced appressoria-like structures, exhibiting swollen tips of germ tubes on the stem surface. There seems to be no significant differences in the pre-infection behavior of F. circinatum on stems between the two pine species.

• Journal of Food Hygiene and Safety
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• v.8 no.2
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• pp.23-32
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• 1993

Species of the genus Fusarium are worldwide in their distribution. They are saprophytes as soil inhabitants and parasites of cultivated plants. Some isolates of certain species car capable of producing mycotoxins. Mycotoxicoses, including moldy corn toxicosis, alimentary toxic aleukia, fusariotoxicosis, and rel mold disease are known to be associated with trichothecene-producing fungi. Historically severe epidemic of cereal scab occred in the southern part of Korea in 1963. The epidemic caused a social problem because of not only heavy economic losses but also mycotoxicoses to humans and farm animals. However the toxic principles were remained unknown until some publications in 1980's indicated that trichothecenes and zearalenone were major mycotoxins in Korea cereals contaminated with Fusarium moniliforme have been found to be associated with human and animal disease such as leukoencephalomalacia in horses, pulmonary edema in swine and esophageal cancer in humans. High concentrations of fumonisins have been detected in corn samples from high espohoageal cancer risk areas of South Africa and China. Thus fumonisins have been implicated in the etiolgy of human esophageal cancer in those high incidence countries. Recently increase of imported cereals from foreign countries demands to assess the safety of mycotoxins in Korea. The informations on the natural occurrence of mycotoxins are needed to solve the toxicological problems in humans and farm animals associated with the consumption of moldy cereals.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.393-405
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• 2019

Survival factor 1 (Svf1) is a protein involved in cell survival pathways. In Saccharomyces cerevisiae, Svf1 is required for the diauxic growth shift and survival under stress conditions. In this study, we characterized the role of FgSvf1, the Svf1 homolog in the homothallic ascomycete fungus Fusarium graminearum. In the FgSvf1 deletion mutant, conidial germination was delayed, vegetative growth was reduced, and pathogenicity was completely abolished. Although the FgSvf1 deletion mutant produced perithecia, the normal maturation of ascospore was dismissed in deletion mutant. The FgSvf1 deletion mutant also showed reduced resistance to osmotic, fungicide, and cold stress and reduced sensitivity to oxidative stress when compared to the wild-type strain. In addition, we showed that FgSvf1 affects glycolysis, which results in the abnormal vegetative growth in the FgSvf1 deletion mutant. Further, intracellular reactive oxygen species (ROS) accumulated in the FgSvf1 deletion mutant, and this accumulated ROS might be related to the reduced sensitivity to oxidative stress and the reduced resistance to cold stress and fungicide stress. Overall, understanding the role of FgSvf1 in F. graminearum provides a new target to control F. graminearum infections in fields.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.3
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• pp.172-177
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• 2022

Two unrecorded fungi, Diaporthe perseae and Fusarium falciforme, were isolated from soil sampled from Dokdo in Korea. There have been many reports of Diaporthe sp. and Fusarium sp. in mainland Korea but none of them have reported in Dokdo so far. We used the morphological features and two molecular markers including the internal transcribed spacer and translation elongation factor 1-α region to compare and analyze these species with the closely related taxa. As a result, we confirmed that these fungi were unrecorded soil fungi in Korea. Then, the cultural and morphological characteristics such as the conidia of these two fungal species could be clarified. These results are expected to help us to understand the distribution of fungi in Dokdo and manage the Dokdo Island Natural Reserve.