• Animal cells and systems
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• v.3 no.3
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• pp.243-246
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• 1999

A type of symbiosis was previously described from nature in which the gametophytes of Laminariales were endophytic in filamentous red algae. Here we reconstruct this symbiosis for the first time in laboratory culture using zoospores of the kelp, Undaria pinnatifida, and the red alga, Aglaothamnion oosumiense. Zoospores of U. pinnatifida readily attached to A. oosumiense. In 48 h these spores germinated and the initial germ tube penetrated into the host cell wall leaving only an empty zoospore wall outside the host. Within ten days, four to five-celled endophytic gametophytes were present. Zoospores of Laminaria religiosa which were also inoculated into cultures of A. oosumiense rarely attached to the red alga and never became endophytic. Within ten days the free-living gametophytes of L. religiosa on cover slips became fertile and produced young sporophytes. These observations demonstrate the ability of U. pinnatifida to become endophytic, and show differences in host specificity among kelp species.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.536-542
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• 1998

Ten isolates of the orchid mycorrhizal fungi were isolated from the roots of Korean native orchid plants (Cymbidium goeringii) which inhabitate mainly in southern and western areas of Korea. The growth rates and color of the isolates in potato dextrose agar (PDA) were various. Microscopic observations of the hyphae isolated were identified as Rhizoctonia repens and R. endophytica var endophytica or their related species. R. repens was isolated from the roots of the Korean native orchids, but R. endophytica var endophyica was only isolated from the roots of the commercial orchids introduced from foreign countries. Also, the polymorephic patterns of genomic DNA extracted from selected isolates were compared with those of DNA extracted from the orchid mycorrhizal fungi isolated previously and similar band patterns were observed among those isolates. Five isolates of R. repens were selected and cultured at the oatmeal agar for investigating their symbiosis with orchid plants. The symbiotic specificity between orchid plants and isolated orchid mycorrhizal fungi was observe by growing orchids about six months in the greenhouse. The symbiotic responses of the commercial orchid plants with selected isolates were quite different form different isolates due to the genetic variations.

• Animal cells and systems
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• v.15 no.4
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• pp.315-324
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• 2011

The actiniarian sea anemone, Entacmaea quadricolor, and the scleractinian coral, Alveopora japonica, host symbiotic dinoflagellates belonging to the genus Symbiodinium (Freudenthal). We studied the host-symbiont specificity of these two anthozoan hosts in the northwestern Pacific Ocean. Symbionts within the two hosts were identified using partial large subunit (LSU) ribosomal DNA (rDNA) and complete internal transcribed spacers (ITS) 1 rDNA regions. The host, E. quadricolor, was identified using the partial LSU rDNA molecular marker. Genetic analysis showed that E. quadricolor only harbors dinoflagellates belonging to subclade C1/3 of the genus Symbiodinium. Moreover, no genetic variation was detected among the symbionts of E. quadricolor within the study region (Korea and Japan), even though the two distant sites were separated by more than 1000 km, at collection depths of 1 m in shallow and 13-16 m in deep water. Whilst scleractinian corals host multiple Symbiodinium clades in tropical waters, A. japonica, sampled over a wide geographical range (800 km) within the study region, only hosts Symbiodinium sp. clade F3. The high specificity of endosymbionts in E. quadricolor and A. japonica within the northwestern Pacific Ocean could be accounted for because symbiotic dinoflagellates within the host anemones appear to be acquired maternally, and the Kuroshio Current might affect the marine biota of the northwestern Pacific. However, the consistency of the symbiotic relationships between these two anthozoan hosts and their endosymbionts could change after climate change, so this symbiotic specificity should be monitored.

• Current Research on Agriculture and Life Sciences
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• v.11
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• pp.121-132
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• 1993

This study was carried out to research the effect of the chemotaxis of Bradyrhizobium japonicum KCTC 2422 and its mutant toward soybean root exudate and to elucidate the effect of the lectin of host specificity (Host Recognition) in soybean-Bradyrhizobium symbiosis. The results obtained were as follows: The homogeneities of the purified lectins from soybean and pea seed was ascertained chromatographically and electrophoretically. Gel electrophoresis of soybean lectin in the presence of sodium dodecyl sulfate appeared a single protein band, whereas pea lectin appeared two protein bands. Soybean lectin from 2 cultivars formed immunoprecipitin arcs at same position with anti-soybean lectin rabbit IgG, but pea lectin did not form immunoprecipitin lines with anti-soybean lectin rabbit IgG. Chemotactic responses of KCTC 2422, LPN-100 and LCR-101 toward proline in capillary assays were 3.1, 1.3 and 1.0-fold above background, respectively. The chemotactic responses of KCTC 2422, LPN-100, and LCR-101 toward Paldal crude root exudate in capillary assays were 3.5, 1.4 and 1.4-fold above background, respectively. The present work shows that B. japonicum and its mutants are capable of very different responses toward root exudate fraction. The chemotactic responses of KCTC 2422 was most with neutral fraction, least with anionic fraction and intermediate with cationic fraction. The nitrogenase activity of soybean nodule was shown in 15days after inoculation with LCR-101. However, we couldn't find out the nodules when soybean was inoculated with LPN-100. From these result we can suppose that the chemotaxis of Bradyrhizobium plays inportant the role of forming the nodule (host recognition) in the soybean-B. japonicum symbiosis.

• The Korean Journal of Mycology
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• v.21 no.3
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• pp.235-245
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• 1993

The symbiotic properties of arbuscular mycorrhizal fungi(AMF) such as the absence and/or presence of symbiosis, spore density, and six factors of phycochemical properties of soil were investigated in the rhizosphere of seven sand dune plants and three control plants around Kum river. The infection of AMF was confirmed in all plants. Three genera, nine species of the AMF spores were identified in the sand dune; Ac. scrobiculata, G. aggregatum, G. convolutum, G. diaphanum, G. dimophicum, G. geosporum, G. vesiculiferum, G. tortuosum, S. pachycaulis. All of them were also found in the control, but S. pachycaulis were only separated in the sand dune. In the control, three genera, four species were identified; G. flavisporum, Gi. margarita, Sc. gregaria. Sc. persica. The species specificity was not found between the sand dune plant and AMF. However, the AMF was thought to be correlated with the soil factors. The spore density was stimulated with increase of the organic matter and the nitrogen content, but inhibited with the water content and the phosphorus content. In respect of the seasonal factor, the spore density was increased in the late growth period of plants.

• Mycobiology
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• v.41 no.3
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• pp.121-125
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• 2013

Arbuscular mycorrhizal fungi (AMF) have mutualistic relationships with more than 80% of terrestrial plant species. This symbiotic relationship is ancient and would have had important roles in establishment of plants on land. Despite their abundance and wide range of relationship with plant species, AMF have shown low species diversity. However, molecular studies have suggested that diversity of these fungi may be much higher, and genetic variation of AMF is very high within a species and even within a single spore. Despite low diversity and lack of host specificity, various functions have been associated with plant growth responses to arbuscular mycorrhizal fungal colonization. In addition, different community composition of AMF affects plants differently, and plays a potential role in ecosystem variability and productivity. AMF have high functional diversity because different combinations of host plants and AMF have different effects on the various aspects of symbiosis. Consequently, recent studies have focused on the different functions of AMF according to their genetic resource and their roles in ecosystem functioning. This review summarizes taxonomic, genetic, and functional diversities of AMF and their roles in natural ecosystems.

• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.25-32
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• 1997

This study was carried out to research the biological characteristics among rhizobia and soybean seed and root lectins, and to obtain a basic imformation of host specificity in biological nitrogen symbiosis system. The results obtained were as follows: Purified seed lectin from soybean varieties of paldal, backwoon and hwangkeum formed immunoprecipitin lines with standard soybean seed lectin and the root lectins from soybean seedlings immunoelectrophoretically. Soybean seed and root lectins interacted with Rhizobium japonicum and Bradyrhizobium japonicum, but didn't interacted with Rhizobium. viceae, whereas pea lectin conjugated with R. viceae, but didn't bind with R. japonicum and B. japonicum. Lipopolysaccharides of B. japonicum and R. viceae were fractionated into LPS I and LPS II on the sephadox G-50. Lipopolysaccharides from B. japonicum showed rhe binding acitivity both with soybean seed lectin and root lectin, but those from R. viceae didn't show it with soybean seed and root lectins.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.551-555
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• 1997

This experiment was carried out to elucidate the biological activity and absorption characteristics of flavonoids in Rhizobium and Bradyrhizobium and to obtain basic information on host specific nodulation by flavonoids in rhizobium-legume symbiosis. The purpose of the present study was to explore the biological activity and the flavonoid absorption indicates that host-specificity is induced by flavonoids in symbiotic nitrogen fixation. Biological activity increased by daidzein and genistein treatment on B. japonicum KCTC 1539 whereas decreased by luteolin treatment but increased by luteolin treatment on R. meliloti whereas decreased by daidzein and genistein treatment. Daidzein and genistein are absorbed by B. japonicum, KCTC 1539 at higher rate than other flavonoids. Especially, luteolin was absorbed at a least rate. Luteolin are absorbed by R. meliloti KCTC 2353 at higher rate than other flavonoids. Especially, daidzein and genistein was absorbed at a least rate.

• Molecules and Cells
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• v.40 no.1
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• pp.17-23
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• 2017

Mitogen-activated protein kinase (MAPK) signaling cascades play critical roles in various cellular events in plants, including stress responses, innate immunity, hormone signaling, and cell specificity. MAPK-mediated stress signaling is also known to negatively regulate nitrogen-fixing symbiotic interactions, but the molecular mechanism of the MAPK signaling cascades underlying the symbiotic nodule development remains largely unknown. We show that the MtMKK5-MtMPK3/6 signaling module negatively regulates the early symbiotic nodule formation, probably upstream of ERN1 (ERF Required for Nodulation 1) and NSP1 (Nod factor Signaling Pathway 1) in Medicago truncatula. The overexpression of MtMKK5 stimulated stress and defense signaling pathways but also reduced nodule formation in M. truncatula roots. Conversely, a MAPK specific inhibitor, U0126, enhanced nodule formation and the expression of an early nodulation marker gene, MtNIN. We found that MtMKK5 directly activates MtMPK3/6 by phosphorylating the TEY motif within the activation loop and that the MtMPK3/6 proteins physically interact with the early nodulation-related transcription factors ERN1 and NSP1. These data suggest that the stress signaling-mediated MtMKK5/MtMPK3/6 module suppresses symbiotic nodule development via the action of early nodulation transcription factors.

• Mycobiology
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• v.49 no.5
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• pp.461-468
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• 2021

The genus Laccaria (Hydnangiaceae, Agaricales) plays an important role in forest ecosystems as an ectomycorrhizal fungus, contributing to nutrient cycles through symbiosis with many types of trees. Though understanding Laccaria diversity and distribution patterns, as well as its association with host plants, is fundamental to constructing a balanced plant diversity and conducting effective forest management, previous studies have not been effective in accurately investigating, as they relied heavily on specimen collection alone. To investigate the true diversity and distribution pattern of Laccaria species and determine their host types, we used four different approaches: specimen-based analysis, open database search (ODS), NGS analysis, and species-specific PCR (SSP). As a result, 14 Laccaria species have been confirmed in Korea. Results regarding the species distribution pattern were different between specimen-based analysis and SSP. However, when both were integrated, the exact distribution pattern of each Laccaria species was determined. In addition, the SSP revealed that many Laccaria species have a wide range of host types. This study shows that using these four different approaches is useful in determining the diversity, distribution, and host of ECM fungi. Furthermore, results obtained for Laccaria will serve as a baseline to help understand the role of ECM fungi in forest management in response to climate change.