• The Plant Pathology Journal
• /
• v.34 no.2
• /
• pp.113-120
• /
• 2018

Chlorella, one single-cell green algae organism that lives autotrophically by photosynthesis, can directly suppress some plant diseases. The objective of this study was to determine whether pre-spraying with Chlorella fusca suspension could induce systemic acquired resistance (SAR) in cucumber plants against anthracnose caused by Colletotrichum orbiculare. In order to illustrate SAR induced by algae, infection structures in host cells were observed under a transmission electron microscope (TEM). Cytological changes as defense responses of host mesophyll cells such as accumulation of vesicles, formation of sheath around penetration hyphae, and thickness of cell wells adjoining with intracellular hyphae were demonstrated in cucumber leaves. Similar defense responses were also found in the plant pre-treated with DL-3-aminobutyric acid, another SAR priming agent. Images showed that defense response of host cells was scarcely observed in untreated leaf tissues. These cytological observations suggest that C. fusca could induce SAR against anthracnose in cucumber plants by activating defense responses of host cells.

• Mycobiology
• /
• v.41 no.2
• /
• pp.67-72
• /
• 2013

Pathogenic microbes secrete various enzymes with lipolytic activities to facilitate their survival within the host. Lipolytic enzymes include extracellular lipases and phospholipases, and several lines of evidence have suggested that these enzymes contribute to the virulence of pathogenic fungi. Candida albicans and Cryptococcus neoformans are the most commonly isolated human fungal pathogens, and several biochemical and molecular approaches have identified their extracellular lipolytic enzymes. The role of lipases and phospholipases in the virulence of C. albicans has been extensively studied, and these enzymes have been shown to contribute to C. albicans morphological transition, colonization, cytotoxicity, and penetration to the host. While not much is known about the lipases in C. neoformans, the roles of phospholipases in the dissemination of fungal cells in the host and in signaling pathways have been described. Lipolytic enzymes may also influence the survival of the lipophilic cutaneous pathogenic yeast Malassezia species within the host, and an unusually high number of lipase-coding genes may complement the lipid dependency of this fungus. This review briefly describes the current understanding of the lipolytic enzymes in major human fungal pathogens, namely C. albicans, C. neoformans, and Malassezia spp.

• Korean journal of applied entomology
• /
• v.19 no.1 s.42
• /
• pp.11-20
• /
• 1980

Percent penetration on a specific rice variety was more affected by blast fungus isolate or predisposition temperature than by temperature and isolate combinations. A susceptible variety tested remained continuously susceptible regardless of whether the variety was grown at different temperature regimes and exposed to isolates/races with differences in pathogenicity and virulence. The expression of virulence by a particular blast fungus isolate race was observed to be changed by subjecting rice host plants to different predisposing temperature conditions prior to inoculation.

• Korean Journal Plant Pathology
• /
• v.1 no.2
• /
• pp.122-127
• /
• 1985

Three rice cultivars, Aichi-asahi, Toyotama and Yamabiko, possessing a resistance gene $Pi-\alpha$ were evaluated for penetration, hyphal growth in the leaf epidermis and lesion formation using 6 isolates of Pyricularia oryzae by treating pre- and post disposing temperatures of $23/15^{\circ}C\;and\;29/21^{\circ}C$ (day/night) regimes, respectively. Percent penetration of the fungus was higher on the seedlings disposed at $29/21^{\circ}C$ regime and more lesions were formed at 7 days after inoculation than at $23/15^{\circ}C$ regime. Degree of hyphal growth and number of host cells with hyphal growth were remarkably increased from 72 to 96 hr after inoculation at $29/21^{\circ}C$ regime. However, lesion formation on the seedlings disposed at $23/15^{\circ}C$ regime was delayed, possibly as a result of the suppressed hyphal growth until 96 hr after inoculation.

• Parasites, Hosts and Diseases
• /
• v.39 no.1
• /
• pp.49-56
• /
• 2001

Excretory/secretory proteins (ESP) from Toxoplasma gondii were analyzed to define the function in the penetration process into host cells. Whole ESP obtained at 37$^{\circ}C$ were composed of 15 bands with molecular mass of 110, 97, 86, 80, 70, 60, 54, 42, 40, 36. 30, 28, 26, 22, and 19 kDa. Five ESP of 86, 80, 42, 36, and 28 kDa were reacted with monoclonal antibodies (mAb). named as Tg386 (microheme), Tg485 (surface membrane), Tg786 (rhoptry), Tg378, and Tg556 (both dense granules), respectively. The ESP was released by a temperature-dependent/-independent manner and all at once whenever ready to pour out except Tg786. Each ESP was not exhausted within the parasite but the amount was limited. Tg786 was released continuously with increment, whereas Tg378 and Tg556 were ceased to release after 3 and 4 hr, Dense granular Tg378 and Tg556 were released spontaneously and constitutively before the entry into host cells also. The entry of T. gondii was inhibited by all the mAbs differentially. And the parasite deprived of ESP was inhibited to enter exponentially up to 90.1%. It is suggested that ESP play an essential function to provide appropriate environment for the entry of the parasite into host cells.

• The Plant Pathology Journal
• /
• v.37 no.2
• /
• pp.87-98
• /
• 2021

To establish an infection, fungal pathogens must recognize diverse signals from host surfaces. The rice blast fungus, Magnaporthe oryzae, is one of the best models studying host-pathogen interactions. This fungus recognizes physical or chemical signals from the host surfaces and initiates the development of an infection structure called appressorium. Here, we found that protein MoAfo1(appressorium formation, MGG_10422) was involved in sensing signal molecules such as cutin monomers and long chain primary alcohols required for appressorium formation. The knockout mutant (ΔMoafo1) formed a few abnormal appressoria on the onion and rice sheath surfaces. However, it produced normal appressoria on the surface of rice leaves. MoAfo1 localized to the membranes of the cytoplasm and vacuole-like organelles in conidia and appressoria. Additionally, the ΔMoafo1 mutant showed defects in appressorium morphology, appressorium penetration, invasive growth, and pathogenicity. These multiple defects might be partially due to failure to respond properly to oxidative stress. These findings broaden our understanding of the fungal mechanisms at play in the recognition of the host surface during rice blast infection.

• Journal of Korean Society of Forest Science
• /
• v.99 no.6
• /
• pp.871-877
• /
• 2010

This study was conducted to investigate the effects of host tree species, temperature and humidity on ex vitro for seed germination in endangered species of Loranthus tanakae. In addition, we compared seed shapes between Loranthus tanakae and Viscum album that we could have easily shown in ex vitro condition. Seeds were germinated after one week inoculation and followed to develop radicles. Seed germination rates of Loranthus tanakae were 80~95% in most of the experimental conditions. The highest rate of holdfast penetrated to host plants was 72% in Populus alba var. pyramidalis among 13 different species tested at $20^{\circ}C$. Also the rates of their penetration were 57% in Morus bombycis, 55% in Acer palmatum and 42% in Castanea crenata at $20^{\circ}C$. Seeds were germinated under condition without irrigation and followed to withered in 12 weeks later. Stages of seed germination of the Loranthus tanakae were followed by radicle induction, holdfast development, haustorium formation and penetration in order in total period of 14 weeks.

• The Plant Pathology Journal
• /
• v.23 no.3
• /
• pp.203-209
• /
• 2007

Infection structures were observed using a fluorescence microscope at the penetration sites on the leaves of potato plants pre-inoculated with the bacterial strains Pseudomonas putida TRL2-3, Micrococcus luteus TRK2-2, and Flexibacteraceae bacterium MRL412, which mediated an induced systemic resistance on potato plants against late blight disease caused by Phytophthora infestans. In order to compare the infection structures on the leaves expressing systemic acquired resistance, the leaves of potato plants pre-treated with DL-3-amino butyric acid (BABA) were also observed after challenge inoculation with the same pathogen. The infection structures were investigated. The total number of germination and appressorium formation of P. infestans were counted. Furthermore, the frequencies of fluorescent epidermal cells at the penetration sites, which indicate a defense response of plant cell, were estimated. There were no differences on the germination rates of the fungal cysts among the untreated control, BABA pre-treated, and bacterial strains pre-inoculated plants. However, appressorium formation was slightly decreased on the leaves of BABA pre-treated plants compared to those of untreated as well as bacterial strains pre-inoculated plants. Furthermore, the frequencies of fluorescent cells of BABA pre-treated and bacterial strains pre-inoculated were higher than that of untreated plants, indicating an active defense reaction of the host cells against the fungal attack. On the other hand, the pre-treatment with BABA caused a stronger fluorescent of epidermal cells at the penetration sites compared to the pre-inoculation with the bacterial strains. Interestingly, the frequency of fluorescent cells by BABA, however, was lower than that by the bacterial strains. Based on the results it is suggested that the infection structures showing resistance reaction on the leaves of potato plants were different between by pre-inoculation with bacterial strains and by pre-treatment with BABA against the late blight pathogen.

• Journal of Animal Science and Technology
• /
• v.48 no.6
• /
• pp.785-796
• /
• 2006

This study was designed to evaluate the changes in sperm motility, viability, HOST(hypo-osmotic swelling test), IVP(in vitro penetration), SCSA(sperm chromatin structure assay) during storage of liquid semen collected from boars with different farrowing rates using AI, and to find the relationship between boar fertility through AI and sperm diagnostic parameters during semen storage. The results of HOST were significantly decreased according to the increasing of in semen storage days and the results of IVP were significantly decreased at 3 days of semen storage (P<0.05). The %Red was significantly different among the >80%, 70󰠏80% and <70% farrowing rate group at semen storage day 6(P<0.05). The correlation coefficients between the %Red and farrowing rate were increased according to the semen storage. In conclusion, these results suggest that the sperm parameters evaluated in these studies may be useful indicators to predict the fertility of AI and evaluate the semen quality in boars.

• Korean Journal of Veterinary Research
• /
• v.9 no.1
• /
• pp.71-78
• /
• 1969

The present studies were undertaken to determine accurately whether Korean native fresh-water shrimps can serve as the second intermediate host of Clonorchis sinensis. The experimental results obtained were as follows; 1. Metacercaria of Clonorchis sinensis was not discovered in 36 Macrobranchium nipponensis (De Hann), 1992 Palaemon paucidens (De Hann) and Palaemon madestus Heller, and 860 Caridina leucastica Stimpson, collected in Kimhae district, which were digested in artificial gastric juice, using binocular dissecting microscope. 2. Cercariae of the Chinese liver fluke could not approach the body wall of young shrimps due to streaming caused by their motion. 3. Young Palaemon spp. of 247 were divided into two groups and placed in two different room aquariums, one is at high temperature, the other is normal. Then they were contacted with the cercariae. Only 11 degenerated metacercariae were found in 9 Palaemon spp. It was suggested that they had died immediately or within a few days after penetration. Furthermore the temperature did not affect the infective ratio. 4. At the field experimental aquarium, no metacercaria of Clonorchis sinensis was discovered tn 100 Palaemon spp. which had been brought into contact with 5000 Parafossarulus manchouricus two trials. 5. Specific changes in the cercariae mixed with the extract of shrimps meat were not observed through the dissecting microscope. 6. These results suggest that the Korean native shrimps cannot serve as the intermediate host of Clonorchis sinensis.