• Korean journal of applied entomology
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• v.5_6
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• pp.19-26
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• 1968

Results obtained from the observation of 1,000 matured resting conidia of Pyricularia oryzae CAV. were as fellows. The percentage of a condium conitaining was 95.5, while that of a multinucleate conidium was 4.5. Formation of the three-celled mature conidium containing a nucleus in each cell, which was derived from the immatured conidium, could be recognized. Chromosomes could be observed in the conidium when the nuclear division took place. The number of chromosomes was n=3, 4, 5 or 6 but rile majority was 5. The nucleus was moved into the germ-tube from the conidium by following ways: (a) a resting nucleus divided into two nuclei in the conidium and one of them was moved into the germ-tube. The other nucleus remained in the conidium (43 per cent): (b) a nucleus was moved into the germ-tube from the conidium without nuclear division (57 Per cent). The appressorium without a nucleus was abundantly observed when stain was made. However, tile number of a mononucleate appressorium was 476 out of 500 appressoria which had nuclear sap. On the ground of this experiment, we could support the conidium of blast fungus contained mononucleus and also homokaryon seemed to b: appealed on the conidia even though those were multilocular. As the results, it could be concluded that use of inoculum derived from single spore isolate was reasonable for any experiments in the rice blast fungus.

• Korean journal of applied entomology
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• v.47 no.2
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• pp.169-174
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• 2008

The growth characteristics of Paecilomyces tenuipes according to the passage in the two kind of liquid media were investigated by comparing the mycelium and conidium formation degrees. The potato dextrose broth medium and the silkworm larvae medium containing the silkworm powder were used as the liquid media, and the potato dextrose agar medium and the brown rice medium containing the powder of silkworm pupa were used as the solid media. The conidium formation degree in liquid media differed by the passages but that in solid media was not. This suggested that the passage in liquid media did not affect significantly the conidium formation in solid media. When the brown rice media were inoculated with the concentration of $1{\times}10^{10}$ conidia/ml, $1{\times}10^8$ conidia/ml and $1{\times}10^6$ conidia/ml, respectively, the conidium formation degrees were similar. This indicated that the optimal inoculation concentration of conidium to the brown rice media is $1{\times}10^6$ conidia/ml.

• Korean Journal Plant Pathology
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• v.13 no.1
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• pp.30-36
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• 1997

The effects of carbon and nitrogen sources on the mycelial growth and sporulation of microconidia and chlamydospores of five isolates of Cylindrocarpon destructans (Zinssm.) Scholten causing root rot of Panax ginseng were studied. For the carbon sources, fructose, glucose, maltose, and sucrose in Czapek-Dox broth showed good mycelial growth of 178∼201 mg in dry weight compared with 64 mg of the control. The best carbon sources tested for conidial formation were sucrose and maltose with 2.75 and 3.03 log conidia/ml, respectively. For the nitrogen sources, aspartic acid, NaNO3, KNO3, arginine, threonine, and leucine increased mycelial growth of the fungi to 208∼231 mg in dry weight without significant difference (p=0.05) among them. Meanwhile the growth with cystine was poor (26.3 mg dry weight), and no conidium and chlamydospore were formed. Maximum microconidial formation was observed in the media with NaNO3 and KNO3 as 3.37 and 3.35 log conidia/ml, and for the chlamydospore formation the (NH4)2SO4-containing medium and the nitrogen-absent medium were the best as 3.40 and 3.57 log chlamydospores/ml, respectively. No conidium was found in the medium without nitrogen sources, in which chlamydospore formation increased 6 times more than in the nitrogen-amended medium. However, deletion of carbon source in the medium did not affect on the formation of conidia and chlamydospores of C. destructans.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.15-15
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• 2014

Fusarium graminearum (teleomorph Gibberella zeae) is an important plant pathogen that causes head blight of major cereal crops such as wheat, barley, and rice, as well as causing ear and stalk rot on maize worldwide. Plant diseases caused by this fungus lead to severe yield losses and accumulation of harmful mycotoxins in infected cereals [1]. Fungi utilize spore production as a mean to rapidly avoid unfavorable environmental conditions and to amplify their population. Spores are produced sexually and asexually and their production is precisely controlled. Upstream developmental activators consist of fluffy genes have been known to orchestrate early induction of condiogenesis in a model filamentous fungus Aspergillus nidulans. To understand the molecular mechanisms underlying conidiogenesis in F. graminearum, we characterized functions of the F. graminearum fluffy gene homologs [2]. We found that FlbD is conserved regulatory function for conidiogenesis in both A. nidulans and F. graminearum among five fluffy gene homologs. flbD deletion abolished conidia and perithecia production, suggesting that FlbD have global roles in hyphal differentiation processes in F. graminearum. We further identified and functionally characterized the ortholog of AbaA, which is involved in differentiation from vegetative hyphae to conidia and known to be absent in F. graminearum [3]. Deletion of abaA did not affect vegetative growth, sexual development, or virulence, but conidium production was completely abolished and thin hyphae grew from abnormally shaped phialides in abaA deletion mutants. Overexpression of abaA resulted in pleiotropic defects such as impaired sexual and asexual development, retarded conidium germination, and reduced trichothecene production. AbaA localized to the nuclei of phialides and terminal cells of mature conidia. Successful interspecies complementation using A. nidulans AbaA and the conserved AbaA-WetA pathway demonstrated that the molecular mechanisms responsible for AbaA activity are conserved in F. graminearum as they are in A. nidulans. F. graminearum ortholog of Aspergillus nidulans wetA has been shown to be involved in conidiogenesis and conidium maturation [4]. Deletion of F. graminearum wetA did not alter mycelial growth, sexual development, or virulence, but the wetA deletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from the F. graminearum wetA deletion mutants was reduced. The wetA deletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidia dormancy by suppressing microcycle conidiation in F. graminearum. In A. nidulans, FlbB physically interacts with FlbD and FlbE, and the resulting FlbB/FlbE and FlbB/FlbD complexes induce the expression of flbD and brlA, respectively. BrlA is an activator of the AbaA-WetA pathway. AbaA and WetA are required for phialide formation and conidia maturation, respectively [5]. In F. graminearum, the AbaA-WetA pathway is similar to that of A. nidulans, except a brlA ortholog does not exist. Amongst the fluffy genes, only fgflbD has a conserved role for regulation of the AbaA-WetA pathway.

• The Plant Pathology Journal
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• v.39 no.4
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• pp.361-373
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• 2023

In plant-pathogen interactions, Magnaporthe oryzae causes blast disease on more than 50 species of 14 monocot plants, including important crops such as rice, millet, and most 15 recently wheat. M. oryzae is a model fungus for studying plant-microbe interaction, and the main source for fungal pathogenesis in the field. Here we report that MoJMJD6 is required for conidium germination and appressorium formation in M. oryzae. We obtained MoJMJD6 mutants (ΔMojmjd6) using a target gene replacement strategy. The MoJMD6 deletion mutants were delayed for conidium germination, glycogen, and lipid droplets utilization and consequently had decreased virulence. In the ΔMojmjd6 null mutants, global histone methyltransferase modifications (H3K4me3, H3K9me3, H3K27me3, and H3K36me2/3) of the genome were unaffected. Taken together, our results indicated that MoJMJD6 function as a nuclear protein which plays an important role in conidium germination and appressorium formation in the M. oryzae. Our work provides insights into MoJMJD6-mediated regulation in the early stage of pathogenesis in plant fungi.

• Journal of Microbiology and Biotechnology
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• v.3 no.2
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• pp.134-138
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• 1993

Monascus anka 732Y3 was induced from Monascus anka KFCC 11832 (IFO 4478, ATCC 16360) by ultra-violet light irradiation. The growth of this new fungus is frequently more dependent on sexual propagation than asexual propagation, compared with that of its parental strain, M. anka KFCC 11832. Less conidia than those of M. anka KFCC 11832 were observed by a microscope. The optical density of the red pigments ($OD_{500}$) produced by M. anka 732Y3 was 157, which was about 10 times higer than that of M. anka KFCC 11832. Such high production of the red pigments by the mutant could be explained by the following observations.

• Mycobiology
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• v.42 no.1
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• pp.1-5
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• 2014

The typical life cycle of filamentous fungi commonly involves asexual sporulation after vegetative growth in response to environmental factors. The production of asexual spores is critical in the life cycle of most filamentous fungi. Normally, conidia are produced from vegetative hyphae (termed mycelia). However, fungal species subjected to stress conditions exhibit an extremely simplified asexual life cycle, in which the conidia that germinate directly generate further conidia, without forming mycelia. This phenomenon has been termed as microcycle conidiation, and to date has been reported in more than 100 fungal species. In this review, first, we present the morphological properties of fungi during microcycle conidiation, and divide microcycle conidiation into four simple categories, even though fungal species exhibit a wide variety of morphological differences during microcycle conidiogenesis. Second, we describe the factors that influence microcycle conidiation in various fungal species, and present recent genetic studies that have identified the genes responsible for this process. Finally, we discuss the biological meaning and application of microcycle conidiation.

• Korean Journal of Veterinary Service
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• v.30 no.2
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• pp.283-286
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• 2007

Fungus generally doesn't produce toxic or harmful substances so it has low chances to cause food poisoning. However it leads to change appearance, odor and characteristics of the contaminated foods and result in sanitary risk problems. Therefore the contamination of fungi should be prevented since they are not proper for human consumption. Green fungi with white outline raised from the air cell of cooked eggs which were collected by Gyeongi Livestock Veterinary Service in August, 2006. The results came out after the cultivation using Sabouraud's Dextrose Agar(SDA). The conidium appeared white and monospore, the shape of colony was round and oval. Conidiophore was brown and granulated and wrinkles and formed. It was confirmed as Aspergillus nidulans based on the dying using Lactophenol cotton blue, the observation of septum and vesicle from the grown spores, and rDNA sequencing.

• Mycobiology
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• v.44 no.1
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• pp.63-65
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• 2016

Cylindrocarpon destructans causes root rot disease in ginseng and can survive for a long time, producing chlamydospores. We optimized conditions to induce chlamydospore production from the conidia of C. destructans, isolated from Korean ginseng. This will provide the basis for testing the efficacy of control agents targeting these chlamydospores.

• Korean Journal Plant Pathology
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• v.14 no.2
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• pp.120-124
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• 1998

The conidial germination of Pestaotiopsis theae was occurred in cells attched with pedicels, the inferior cell of conidium. The cells were swollen like a ball, and then germinated in 4 hours under favorable conditions. Generally, it was considered that fifty percent of whole conidia was germinated in the range 6~12 hours. The optimum temperature and pH for conidial germination of P. theae (SP-3) causing leaf blight on sweet persimmon was $25^{\circ}C$ and pH 5, respectively. Conidial germination rate was higher than 90% at 100% relative humidity, but never germinated at a relative humidity lower than 88.5%. Conidial germination was highest at the concentration of 1~4$\times$104 conidia/ml. In case of cultural media, the conidial germination was higher than 90% on PDA, PSA, OME and Leonian agar. There was no relationship between light and conidial germination. It was concluded that the key environmental factors affecting conidial germination of the fungus (SP-3) were temperature and moisture.