• Molecules and Cells
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• v.42 no.7
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• pp.503-511
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• 2019

As sessile organisms, plants have developed sophisticated system to defend themselves against microbial attack. Since plants do not have specialized immune cells, all plant cells appear to have the innate ability to recognize pathogens and turn on an appropriate defense response. The plant innate immune system has two major branches: PAMPs (pathogen associated molecular patterns)-triggered immunity (PTI) and effector-triggered immunity (ETI). The ability to discriminate between self and non-self is a fundamental feature of living organisms, and it is a prerequisite for the activation of plant defenses specific to microbial infection. Arabidopsis cells express receptors that detect extracellular molecules or structures of the microbes, which are called collectively PAMPs and activate PTI. However, nucleotidebinding site leucine-rich repeats (NB-LRR) proteins mediated ETI is induced by direct or indirect recognition of effector molecules encoded by avr genes. In Arabidopsis, plasmamembrane localized multifunctional protein RIN4 (RPM1-interacting protein 4) plays important role in both PTI and ETI. Previous studies have suggested that RIN4 functions as a negative regulator of PTI. In addition, many different bacterial effector proteins modify RIN4 to destabilize plant immunity and several NB-LRR proteins, including RPM1 (resistance to Pseudomonas syringae pv. maculicola 1), RPS2 (resistance to P. syringae 2) guard RIN4. This review summarizes the current studies that have described signaling mechanism of RIN4 function, modification of RIN4 by bacterial effectors and different interacting partner of RIN4 in defense related pathway. In addition, the emerging role of the RIN4 in plant physiology and intercellular signaling as it presents in exosomes will be discussed.

• The Plant Pathology Journal
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• v.17 no.4
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• pp.201-204
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• 2001

Ultrastructural observation was conducted for the cells of oriental cabbage, Brassica campestris ssp. pekinensis 'Chungawang', inoculated simultaneously with Turnip mosaic virus (TuMV-ACT2-4vq) and Ribgrass mosaic virus (RMV-Ca1dn2) which were known as major destructive viruses of oriental cabbage in Korea. In cells infected with RMV alone, the virus particles were located as bundle or scattering in cytosols and vacuoles, which were typical ultrastructures of tobamovirus. Vessels of xylem were compacted with RMV particles. The cells infected only with TuMV had the cluster of virus particles scarcely and the typical potyvirus inclusions of scrolls, pinwheels, tubes and laminated aggregates in cytosols. The TuMV particles were jammed lineally between tonoplasts. In double infection, the two unrelated viruses of TuMV-ACT2-4vq and RMV-CA1dn2 were located together in a cell, and typical properties of each virus were also observed. The potyvirus inclusions and the tobamovirus particles were mixed entirely in cytoplasm. The virus particles of RMV wre presented strikingly near and in the center of potyvirus inclusions. In vascular cells, the tobamovirus particles were located abundantly than those in single infection. The potyvirus inclusions were embedded in the cluster of RMV particles in phloem parenchyma cells and the vascular elements were degenerated severely.

• Proceedings of the Botanical Society of Korea Conference
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• 1993.07a
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• pp.1-36
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• 1993

It is possible to regenerate plants from calli, single cells and protoplasts of numerous species via organogenasis or embryogenesis in cell and tissue culture systems. Also such regeneration of plants can directly occur from cells of explants. However certain plant species has not been yet provided cultures suitable for plant regeneration from cells or tissues. For example, we have to confirm the regenerability of plant from cells before preparing transformed cells for application. Even more, it is very important to notice that regenerated plants in cell and tissue cultures often show structural abnormality. The mojority of those plants is functionally disordered and eventually cases degenerated. One of such examples is vitreous plants which are manifested mainly in the leaves and manifesteds to a lesser extent in the stems and roots. Regenerants in suspension cultures show more frequent vitrification than on gelled media so that relative humidity and water potential are the key factors involved in abnormal morphogenesis in vitro. The other is that somatic embryos formed in media containing BAP or high concentration of sucrose show frequently cotyledon aberrancy such as polycotyledon and born type cotyledon. The embryos with aberrant cotyledon of Codonopsis lanceolata could not germinate or regenerate into plants in many cases. In contrast, the polycotyledon embryos of Aralia cordata germinated in higher percentage than two cotyledonary embryos, but horn type cotyledonary embryos rarely germinated. The major cause of poor germination is the abnormal development of plumule apex meristem.

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

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.106-106
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• 2022

The cone of Red Pine (Pinus densiflora), which has been used as a drug in traditional medicine. Its ethyl acetate fraction was reported to exert antioxidant, anti-melanogenesis, and anti-inflammation activites. Apoptosis of hepatic stellate cells (LX-2) is regarding as a potential strategy for alleviation of hepatic fibrosis. We conducted to investigated whether the treatment of cone has a potential to control of some factors related in apoptosis and autophagy in cell signaling pathways. We suggest that the cone induced apoptosis through confirming the expression levels of genes (cPARP, Bcl-XL, Bax, p53, and caspase-3) in LX-2 cells. Also, the cone may regulate autophagy (LC3, p62, Beclin-1, and ATG12). Remarkably, the treatment of cone may affect to formation of autophagosomes in the immunofluorescence image in live cells. These findings suggest that the ethyl acetate fraction from the cone of Red Pine (P. densiflora) may have potential as an alternative therapeutic agent for the alleviation and prevention of liver fibrosis.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.86-86
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• 2020

The leaves of Staphylea bumalda (S. bumalda) as a deciduous tree distributed in Korea, China and Japan are used to treat respiratory diseases or inflammation. However, there is no scientific research on the immune-enhancing activity of S. bumalda leaves. Thus, in this study, we investigated the effect of water extracts from S. bumalda leaves (SBL) on the macrophage activity using mouse macrophage cells, RAW264.7. SBL increased production of immunomodulators such as NO, iNOS, IL-1β, IL-6, TNF-α and MCP-1 in RAW264.7 cells and activated phagocytic activity of RAW264.7 cells. Inhibition of TLR2 and TLR4 blocked SBL-mediated production of immunomodulators in RAW264.7 cells. In addition, SBL-mediated production of immunomodulators was attenuated by JNK inhibition in RAW264.7 cells. SBL increased JNK phosphorylation, while Inhibition of TLR2 and TLR4 blocked SBL-mediated JNK phosphorylation in RAW264.7 cells. These results are thought to be evidence that SBL activates JNK through stimulation of TLR2 and TLR4 in macrophage to induce the production of immunomodulators. In LPS-stimulated RAW264.7 cells, SBL inhibited over-production of immunomodulators. Summarizing the results, SBL showed immunostimulatory activity under normal conditions and immunosuppressive activity under LPS-induced excessive immune response conditions.

• Animal cells and systems
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• v.4 no.3
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• pp.201-214
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• 2000

Two quite different types of plant cells are analysed with regard to transduction of the gravity stimulus: (i) Unicellular rhizoids and protonemata of characean green algae; these are tube-like, tip-growing cells which respond to the direction of gravity. (ii) Columella cells located in the center of the root cap of higher plants; these cells (statocytes) perceive gravity. The two cell types contain heavy particles or organelles (sataoliths) which sediment in the field of gravity, thereby inducing the graviresponse. Both cell types were studied under microgravity conditions ($10^{-4}$/ g) in sounding rockets or spacelabs. From video microscopy of living Chara cells and different experiments with both cell types it was concluded that the position of statoliths depends on the balance of two forces, i.e. the gravitational force and the counteracting force mediated by actin microfilaments. The actomyosin system may be the missing link between the gravity-dependent movement of statoliths and the gravity receptor(s); it may also function as an amplifier.

• Journal of Plant Biology
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• v.36 no.1
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• pp.29-34
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• 1993

Observation was made on early ontogeny of vascular cambium in the cotyledonary node of Pinus koraiensis seedling in order to clarify the cambial ontogeny of the node which was hardly elongated. In transverse view, the derivatives by the early periclinal divisions at the outer region of the procambial strands differentiated to protophloem with establishing a certain degree of radial seriations. Later, some cells in the central region of the procambial strands begin divide periclinally, eventually the cells, differentiate gradually to the vascular cambium. In tangential view, early procambium is consisted of homogeneous short cells with transverse end walls which are tansformed into the long cells and short cells gradually. The long cells continue intrusive growth and the short cells repeat transverse division. Finally, the long and short cells differentiated to cambial fusiform initials and ray initials respectively. In tangential section, the differentiation pattern of cambial initials resembles that of the stem of Ginkgo biloba. But in transverse view, the characteristics in the origin of vascular cambium of the cotyledonary node resembles that of root. The vascular cambium in cotyledonary node is completed after eleven prophylls were formed.

• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.133-136
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• 2000

To evaluate the biological effects of dykellic acid, a novel apoptosis inhibitor, isolated from microorganism on the plant cells, the cell growth, protein contents, and superoxide dismutase (SOD) activity were investigated in suspension cultures of tobacco photomixotrophic cultured (PM) cells on 12 days after different concentration of chemical treatment. The cells were cultured in MS medium containing 0.7 mg/L 2,4-D, 0.3 mg/L kinetin, 30 g/L sucrose and 200 mM NaCl at $25^{\circ}C$ in the light (100 rpm). Dykellic acid strongly inhibited the cell growth by evaluating the cell fresh wt and the ion conductivity in the medium ($IC_{50}$/, about 20 $\mu$M). The results as inhibition of cell growth and cell wall damage were same. The compound significantly increased the protein contents and the SOD specific activity in proportion with the dosage. The results suggested that dykellic acid may have biological activity in plant cells and tobacco PM cells may be suitable biomaterials for in vitro evaluation of the biological activity of natural products.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.115-120
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• 2002

Xanthomonas axonopodis pv. glycines, the causal agent of bacterial pustule of soybean, induces hypersensitive response (HR) in a non-host plant, hot pepper (Capsicum annuum). A wild-type strain (8ra) and its non-patho-genic mutant (8-13) of X. axonopodis pv. glycines were inoculated into the pepper leaf tissues and their subcellular responses to the bacterial infections were examined by electron microscopy. Intrastructural changes related to HR were found in the leaf tissues infected with 8ra from 8 h after inoculation, characterized by separation of plasmalemma from the cell wall, formation of small vacuoles and vesicles, formation of cell wall apposition, and cellular necrosis. No such responses were observed in the tissues infected with the mutant. In 8ra, the bacterial cells were attached to the cell walls, with the cell wall material dissolved into and appearing to encapsulate the bacterial cells. The bacterial cells later became entirely embedded in the cell wall material. On the other hand, in 8-13, the bacterial cells were usually not attached tightly to the plant cell wall, and no or poor encapsulation of the bacteria by the wall material occurred, although these were encircled by rather loose wall materials at the later stages.