• The Plant Pathology Journal
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• 제24권3호
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• pp.352-356
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• 2008

Root discs of 4-year-old ginseng, Panax ginseng C. A. Meyer, were inoculated with the higher($10^8$ colonyforming units(CFU)/ml) and lower($10^6\;or\;10^5$ CFU/ml) initial inoculum levels of a plant-growth promoting rhizobacterium(PGPR), Paenibacillus polymyxa GBR-1 to examine rot symptom development and bacterial population changes on the root discs. At the higher inoculum level, brown rot symptoms developed and expanded on the whole root discs in which the bacterial population increased continuously up to 4 days after inoculation. In light and electron microscopy, ginseng root cells on the inoculation sites were extensively decayed, which were characterized by dissolved cell walls and destructed cytoplasmic contents. However, no rot symptoms were developed and the bacterial population increased only during the initial two days of inoculation at the lower inoculum level($10^6$ CFU/ml) of P. polymyxa GBR-1. At the lower inoculum level($10^5$ CFU/ml), boundary layers with parallel periclinal cell divisions, structurally similar to wound periderm, were formed internal to the inoculation sites, beneath which the cells were intact containing numerous normal-looking starch granules and no disorganized cell organelles, suggesting that these structural features may be related to the suppression of symptom development, a histological defense mechanism.

• Journal of Plant Biology
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• 제37권3호
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• pp.317-323
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• 1994

The calluses formed on the surface of a quarter-girdled Robinia pseudoacacia stems have been shown to originate from immature xylem cells and preexisting cambial cells. The cellus is not only formed by periclinal and anticlinal divisions of radial cells, but also axial cells. In tangential view, the callus at initial stage showed heterogeneous structure composed of long and short cells and then homogeneous one with short cells. Some cells of homogeneous structure in middle region of callus at early stage is later elongated and others mainly divided in trasverse plane. In the result the homogeneous structure becomes into a heterogeneous one. Subsequently, the long cells in heterogeneous structures elongated further and became fusifrom initials, and the short cells divided transversely became ray initials. The appearence of homogeneous and heterogeneous structure in the callus on debarked stem without organ elongation is almost similar to that of the structure in the procambium of young stem which is elongating extensively. Eventually, the ontogeny of vascular cambium in wound callus resembles that of a young stem grown normally, although the debarked stem does not grow in length but in girth and the young stem elongates activity. These findings mean that the active intrusive growth of short procambial cells occurs during the differentiation of fusiform cambial cells.

• The Plant Pathology Journal
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• 제15권2호
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• pp.127-130
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• 1999

Cytological changes of cowpea root at the early stage of root nodule formation (within 5 days after inoculation) were viewed by light and electron microscopy. The root region affected by the rhizobial infection, which was composed of a redial array of cortical cells, had prominent cell divisions, mostly anticlinal in the inner cortical cells and in addition oblique and periclinal in the outer cells. An infected root hair cell (or root hair-producing epidermal cell) had numerous infection threads and degenerated cytoplasm. Module meristem was formed adjacent to the infected root hair cell, and characterized by dense cytoplasm, prominent nucleus, numerous small vacuoles, and increased plastids, containing infection threads as well. Bacterial cells were dividing inside the infection thread, the wall materials of which appeared to be dissolved ad accumulated in small vacuoles. inner cortical cells contiguous to the nodule meristem appeared to be actively dividing and dedifferentiating; however, they were not infected by the rhizobia. These structural characteristics are similar to those in the Bradyrhizobium-soybean association previously reported, and may reflect the similar cytological process in cowpea in the early nodule formation.

• Molecules and Cells
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• 제39권7호
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• pp.524-529
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• 2016

Controlling the production of diverse cell/tissue types is essential for the development of multicellular organisms such as animals and plants. The Arabidopsis thaliana root, which contains distinct cells/tissues along longitudinal and radial axes, has served as an elegant model to investigate how genetic programs and environmental signals interact to produce different cell/tissue types. In the root, a series of asymmetric cell divisions (ACDs) give rise to three ground tissue layers at maturity (endodermis, middle cortex, and cortex). Because the middle cortex is formed by a periclinal (parallel to the axis) ACD of the endodermis around 7 to 14 days post-germination, middle cortex formation is used as a parameter to assess maturation of the root ground tissue. Molecular, genetic, and physiological studies have revealed that the control of the timing and extent of middle cortex formation during root maturation relies on the interaction of plant hormones and transcription factors. In particular, abscisic acid and gibberellin act synergistically to regulate the timing and extent of middle cortex formation, unlike their typical antagonism. The SHORT-ROOT, SCARECROW, SCARECROW-LIKE 3, and DELLA transcription factors, all of which belong to the plant-specific GRAS family, play key roles in the regulation of middle cortex formation. Recently, two additional transcription factors, SEUSS and GA- AND ABA-RESPONSIVE ZINC FINGER, have also been characterized during ground tissue maturation. In this review, we provide a detailed account of the regulatory networks that control the timing and extent of middle cortex formation during post-embryonic root development.

• Journal of Plant Biotechnology
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• 제31권4호
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• pp.301-306
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• 2004

마늘 (Allium sativum L.) 다신초를 생물반응기를 이용, sucrose 2%가 포함된 MS 배지에서 3주간 증식시킨 후 microbulb의 형성을 위해 NAA 0.1 mg/L와 sucrose 11%가 포함된 MS 배지에서 9주간 배양하였다. 다신초 증식의 경우, 잎을 제거하지 않았을 때 90% 이상이 과수화되었고 과수화 된 신초의 세포는 크기와 형태가 일정하지 않았으며 microbulb의 형성도 이루어지지 않았다. 신초 배양 3주 후 표피의 부정아 세포에서 분열이 활성화되면서 부정아가 비대되었고 신초의 분열조직에서 수층과 병층으로 분열이 일어나 크게 비대된 후 배양 7주부터 microbulb를 형성하였다. Ploidy analyzer를 이용한 배수성 검정에서 다신초와 microbulb의 피크 모두, 모주 식물의 상대적인 피크와 동일한 위치에서 나타나 배수성의 변이가 없는 것으로 나타나 배양체가 모주 식물과 유전적으로 동일함을 입증하였다.

• The Plant Pathology Journal
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• 제24권4호
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• pp.392-399
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• 2008

Detached chili pepper fruits were inoculated with the conidial suspension of Colletotrichum acutatum JC-24 simultaneously (simultaneous inoculation, SI) and at delayed time (delayed inoculation, DI) after wounding with (delayed wound inoculation, DWI) or without additional wounding (delayed non-wound inoculation, DNI) at the inoculation time. Disease severity was significantly lowered by DNI, compared to SI. By DNI, the disease reduction rates were proportional with the length of delayed time, and greater at the high temperature range (18, 23 and $28^{\circ}$) than at the low temperature ($13^{\circ}$) tested. DWI was also effective in reducing the disease severity especially at 18oC; however, its effectiveness was lower than for DNI. In light microscopy, parenchyma cells at the wounding sites were modified structurally, initially forming new cell walls crossing cytoplasm, enlarged with multiple periclinal cell divisions, and finally layered like wound periderms. In DWI, the above structural modifications occurred, showing the restriction of the fungal invasion by the cell walls in enlarged modified cells, while no definite cellular modifications were found with proliferation of fungal hyphae in SI. Sclerenchyma-like cells with thickened cell walls were proliferated around the wounding sites, which were partially dissolved by DWI, probably leading to some disease development. All of these results suggest that the decline of the anthracnose disease in pepper fruit by the delayed inoculations may be derived from the structural modifications related to the healing processes of the previous wound inflicted on the tissues.

• ALGAE
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• 제23권2호
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• pp.119-133
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• 2008

We cultured a tubular marine green alga, originally identified as Capsosiphon groenlandicus (J. Agardh) K.L. Vinogradova, from Amaknak Island, Alaska. The alga had an alternation of heteromorphic generations in which tubular monoecious fronds produced quadriflagellate zoospores and/or biflagellate isogametes. The gametes fused to produce cysts or Codiolum-like zygotes with long, tortuous stalks. Cysts and codiola produced 8-16 aplanospores, which germinated in situ to yield upright fronds. Fronds arising from both aplanospores and zoospores displayed a distinctive development in which non-septate colorless rhizoids from the base of the initially uniseriate, Ulothrix-like filament were transformed into septate uniseriate Ulothrix-like photosynthetic filaments. These transformed filaments then developed new basal non-septate rhizoids. This pattern of rhizoids becoming filaments, which then produced new rhizoids, was repeated to yield a tuft of up to 50 fronds. Periclinal and longitudinal divisions occurred in each filament, starting basally, until the mature tubular thallus was achieved. Pyrenoid ultrastructure revealed several short inward extensions of chloroplast lamellae, each of which was surrounded by pyrenoglobuli. Analysis of ribosomal SSU and ITS sequences placed this alga in the family Ulotrichaceae, order Ulotrichales, together with but as a distinct species from North Atlantic Capsosiphon groenlandicus. Analysis of a partial ITS sequence from authentic Capsosiphon fulvescens, the current name of the type of the genus Capsosiphon, indicated that neither our material nor C. groenlandicus belongs in that genus, and we propose a new genus, Pseudothrix, to accommodate both species. We propose P. borealis for the North Pacific entity formerly called C. groenlandicus and make the new combination P. groenlandica for the Atlantic species.

• The Plant Pathology Journal
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• 제32권4호
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• pp.311-320
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• 2016

Xanthomonas axonopodis pv. glycines (Xag) is a necrotrophic bacterial pathogen of the soybean that causes bacterial pustules and is a nonhost pathogen of the chili pepper. In the current study, chili pepper fruit wound inoculated in planta with Xag 8ra formed necrotic lesions on the fruit surface and induced several structural and chemical barriers systemically in the fruit tissue. The initial defense response included programmed cell death of necrotizing and necrotized cells, which was characterized by nuclear DNA cleavage, as detected by TUNEL-confocal laser scanning microscopy (CLSM), and phosphatidylserine exposure on cell walls distal to the infection site, as detected by Annexin V FLUOS-CLSM. These two responses may facilitate cell killing and enhance transportation of cell wall materials used for cell wall thickening, respectively. The cells beneath the necrotic tissue were enlarged and divided to form periclinal cell walls, resulting in extensive formation of several parallel boundary layers at the later stages of infection, accompanying the deposition of wall fortification materials for strengthening structural defenses. These results suggest that nonhost resistance of chili pepper fruit against the nonhost necrotrophic pathogen Xag 8ra is activated systematically from the initial infection until termination of the infection cycle, resulting in complete inhibition of bacterial pathogenesis by utilizing organspecific in situ physiological events governed by the expression of genes in the plant fruit organ.

• 대한본초학회지
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• 제33권4호
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• pp.43-51
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• 2018

Objectives : Pharbitidis Semen, the seeds of Ipomoea nil (L.) Roth or I. purpurea (L.) Roth, is well-known traditional herbal medicine in Korea. But it is often marketed as a different seed or mixtures of its closely related species. Thus, the present study aims to provide external and micromorphological characters and identification key by using stereoscope (ST) and scanning electron microscope (SEM) for discriminating authentic of Pharbitidis Semen. Methods : A discrimination on external morphological characteristics of sepals, fruits, seeds, and hilum, testa cell micromorphology in the original plants and its congeneric species was carried out using digital calipers, ST, and SEM. Results : Number of valves (degree of apex of each valve), number of seeds per locule, hairy in capsules and size, luster, density of hairy, hilum shape in seeds and shape of cell, anticlinal, periclinal wall in testa may have high discriminative value. The seeds of Ipomoea nil as an original plant of Pharbitidis Semen were distinguished from other species by the relative larger in size, ovoid-trigonous in shape, mostly flabellate or triangular to trapezoid in outline (c.s.), dull, and puberulent in surface and thicken anticlinal wall. Conclusions : On the basis of the results, an identification key of Pharbitidis Semen and closely related species is provided. Our observations suggest that the combination of morphological characters and other studied results could be helpful in the successfully identified authentic herbal medicines. Moreover, micromorphological characters using SEM could be useful for discriminating authentic medicines.

• 원예과학기술지
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• 제28권6호
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• pp.996-1002
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• 2010

'캠벨얼리' 아조변이체의 배수성을 flow cytometry(FCM)를 이용하여 검정하였다. 2배체 포도인 '캠벨얼리'와 4배체 포도인 '거봉'과는 달리 '캠벨얼리'에서 발생한 아조변이 3계통의 경우, 잎에서 2배체와 4배체 peak가 동시에 나타났다. 또한 '캠벨얼리' 포도의 과육과 과피의 배수성은 2배체 peak를 보인 반면, '캠벨얼리' 아조변이체는 과피의 배수성은 2배체로, 과육의 배수성은 4배체로 검정되었다. 정확한 염색체 숫자를 알아보기 위해 '캠벨얼리' 유래 아조변이체, '캠벨어리', '거봉' 포도의 근단 조직 염색체 숫자를 현미경 검경하였다. '캠벨얼리'와 '거봉'은 각각 38, 76개의 염색체로 나타난 반면 아조변이체는 2x=38, 4x=76개의 염색체가 혼재한 것으로 나타났다. '캠벨얼리' 아조변이체의 키메라 형태를 알아보기 위하여 신초정단 분열조직을 현미경 관찰하였다. 대조구로 이용된 2배체 '캠벨얼리'와 4배체 '거봉' 포도는 2개의 tunica 층이 corpus층을 덮고 있었으며, 반면에 아조변이체의 경우 첫번째 tunica 층이 독특하게 분할되어 있었다. '거봉' 포도의 정단분열 조직의 세포 크기는 대체로 '캠벨얼리' 포도보다 더 컸다. 아조변이체의 L-2, L-3 층을 이루고 있는 세포 크기는 4배체인 '거봉' 세포와 유사하였으며 가장 바깥쪽 L-1층을 이루고 있는 세포의 크기는 '캠벨얼리' 포도와 유사한 크기였다. 따라서 본 시험의 결과 '캠벨얼리' 포도 품종에서 발생한 아조변이체들은 2-4-4형 키메라의 가능성이 높은 것으로 판단되었다.