• Journal of Plant Biology
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• 제35권2호
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• pp.173-182
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• 1992

The parasitic flowering plants obtain nutrients and water from their host plants through a parasitic organ, haustorium, which connects both structurally and physiologically host and parasite. The parasitism in angiosperms thus can be understood from the knowledge of the haustorial structure. The haustoria have evolve convergently and independently in several unrelated taxa; therefore, they have similar morphology. Many anatomical studies on the haustoria in several parasites in the pst have been carried out by light microscopy. Ultrastructural studies on the haustoria, which are started from the end of 1060s', have provided new information relating to the phenomenon of parasitism in angiosperms. The purpose of this paper is to introduce and compare the structure of haustoria between parasitic plants. The results may help an understanding of phylogenetic relationships of parasitic angiosperms. The haustoria of some families, such as Santalaceae, Orobancaceae, Scrophulariaceae, Loranthaceae (or Viscaceae), and Convolvulaceae (Cuscuta) will be discussed.

• Applied Microscopy
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• 제17권1호
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• pp.161-168
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• 1987

The elongated filamentous haustorial cells, hyphae, of Cuscuta australis R. Brown penetrated into the vascular tissues of the host plant Trifolium repens L. were studied by the light and electron microscopes. The hyphae reached the host xylem were invaded into the host vessels and then they grew within the host vessels. Finally these hyphae were differentiated into the water conducting elements, xylary hyphae, by thickening of the secondary walls. The hyphae reached the host phloem were branched at the apical regions. These hyphae possessed thin-layered cytoplasm involving the typical features of sieve elements such as the parallel arrays of smooth endoplasmic reticulum, plastids with the clusters of fine starch granules, and mitochondria with the dilated cristae. It was indicated that these hyphae were differentiated into the nutrients conducting elements, phloic hyphae. The structures described were compared with those of other parasitic plants and were discussed in view of the translocation of materials from host to parasite.

• 한국자원식물학회지
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• 제11권3호
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• pp.245-251
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• 1998

Test plants with 10 days old primary leaves were indouclated by shaking infected seedlings with sporulating colonies over them in an inoculation room under the conditions of 20$\pm$1 $^{\circ}C$ with constant illumination of 2.500 lux and 100% realtive humidity. A seeding reaction of 4 days after inoculation appreared in the trisomic types as opposed to Tri-5B line had been symtoms of a fungus 3 days after inoculation. The infection types of 8 days after inoculation were recognized with higher susceptibility to each trisomics in A genomie than B-genome. Tri-2A line showed less condium and there appeared symptoms of a conditions of mottle and formed papilla, and haustorium was not formed. However, Tri-5B line had much condium one overall leaves and showed a symtom like necrosis compared with normal plant. Moreover, Tri-5B line showed high sensitivity and high germination number of condium. These results inferred that resistant gene located on 2A chromosome and susceptibility gene is located on the chromosome 5B.

• 한국산림과학회지
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• 제99권6호
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• pp.871-877
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• 2010

본 연구는 멸종위기에 처한 꼬리겨우살이 종자의 형태적 특징과 발아과정 및 종자발아에 미치는 기주목, 온도, 습도의 영향 및 꼬리겨우살이 종자의 형태적 특징을 관찰하고 일반 겨우살이 종자와의 비교를 위하여 연구를 수행하였다. 꼬리겨우살이 종자발아는 기주목에 접종 1주일 후 원기근을 형성하기 시작하였으며 대부분의 발아조건에서 80~95%의 발아율을 보였다. 종자발아 후 흡기근 침투율은 $20^{\circ}C$ 조건에서 다양한 기주식물 중 신강포플러에서 가장 높은 흡기근 침투율(72%)을 보였으며, 이 외에도 $20^{\circ}C$ 조건에서 산뽕나무, 단풍나무 및 밤나무에서 흡기근 침투율이 각각 57%, 55% 및 42%를 보여 수종과 온도에 따라 흡기근 침투율의 차이가 나타났다. 관수가 없는 조건에서도 종자발아가 진행되었으나 접종 12주 후 꼬리겨우살이 종자와 기주목이 모두 고사하였다. 꼬리겨우살이 종자발아 과정은 원기근 유도${\rightarrow}$흡착기관 발달${\rightarrow}$흡기근 형성 및 침투단계로 총 14주의 기간이 소요되며 꼬리겨우살이가 종자발아를 위해서는 단계별 과정과 긴 기간이 필요한 것으로 보였다.

• Applied Microscopy
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• 제16권2호
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• pp.49-60
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• 1986

Ultrastructures of the large and elongated cells (idioblasts) in the haustorium of a parasitic angiosperm, Cuscuta australis R. Brown growing on the host plant, Trifolium repens L. were investigated by the electron microscopy. The idioblasts were characterized by the presence of a large nucleus, small vacuoles, and dense cytoplasm including a number of various cell organelles such as ribosome, rough endoplasmic reticulum(r-ER), mitochondrion, dictyosome, proplastid, multilamellar structure(MLS), microfilament bundle(MFB), and cytosegresome. Therefore, it is suggested that the idioblasts are metabolical1y very active. Particularly, MLS, MFB, and cytosegresome observed in this study did not appear in the haustorial cells of the other parasitic angiosperms. MLS was transformed into vacuole and also incorporated with cell wall. MFB composed of microfilaments, about each 7.5 nm in diameter, was observed in nucleus and also cytoplasm. Some types of MFB were distinguished on the basis of arrangement of microfilaments. A part of cytoplasm sequestered by stacked cisternae of smooth ER(s-ER), cytosegresome, was altered into a vacuole which was formed by digestion of the sequestered cytoplasm and of cisternae of s-ER. Cell organelles such as MLS, MFB, and cytosegresome were discussed in relation to the metabolic control of the idioblasts.

• Journal of Plant Biology
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• 제36권3호
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• pp.285-292
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• 1993

Cellular compatibility in the self-parasitism of Cuscuta australis R. Brown was studied at the ultrastructural level. The front cells of the haustorium penetrated the host stems independently grew within the host tissues and transformed into elongate, filamentous hyphae. Each hyphal cells contained a large nucleus and dense cytoplasm with abundant cell organelles. Multilamellar structures were contained in the cytoplasm and cell walls of the penetrating hyphal cells. When the hyphal cells did not yet invade the host cells, the middle lamella and the fused cellulosic cell walls of the two partners at the host-parasite interface were preserved well. As the invasion of the parasitic hyphal cells progressed, however, the middle lamella was not found at the interface and the host cell walls and plasma membranes were partially broken down. A hyphal cell penetrated deeply into the host cell had a more darkly stained cytoplasm with numerous of cell organelles. In the host cells attacked by the hyphal cells the limiting membranes of plastids were broken down and several vesicles were arrayed near the cell walls. No plasmodesmatal connections between the host and parasite cell walls were found; however, half-plasmodesmata were observed frequently on the side of the hyphal cell walls. These results suggested that the compatibility response in the self-parasitism of Cuscuta was expressed by cell walls, not by plasmodesmata, between the host and the parasite cells.

• 한국자원식물학회지
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• 제28권6호
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• pp.710-717
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• 2015

Humankind has been searching for medicinal materials from various plant sources in an attempt to treat disease. Mistletoe is one indubitable plant source for these materials due to its effectiveness in treating various diseases, but it has almost disappeared from the mountainous areas of Korea due to excessive harvesting. In this study, in order to select host tree species for Korean mistletoe [Viscum album var. coloratum (Kom.) Ohwi] by seed inoculation and to clarify the effect of host specificity among various tree species were conducted for the purpose of gaining basic information for the artificial cultivation of Korean mistletoe. Almost all the seeds of Korean mistletoe germinated in vitro at the temperature of 15℃. Among host trees used in this study, Prunus mume showed the highest parasitic affinity with inoculated Korean mistletoe, compared with any other host plants. However, treatment of hormones could not increase the low survival rate of Korean mistletoe on the host trees.

• Journal of Forest and Environmental Science
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• 제29권2호
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• pp.173-180
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• 2013

Berries of Korean mistletoe (Viscum album var. coloratum [Kom.] Ohwi) contained one seed, which have, in general, one or two embryos but very rarely three embryos. Mucilaginous substances in berries may help them adhere to the branches of host trees. It was observed that seeds need more than one and half years to develop into normal and healthy seedlings from the time of inoculation. Many factors such as adhesion of berry, thickness of host branch, orientation of haustorial root, etc. influenced the successful development of mistletoe plants. Through the application of six-year observation results on the germination of seeds and growth of seedlings, about 80% of germination rate for mistletoe seeds and 61% of survival ratio for germinated seeds, which is more than 23 times higher in natural conditions, were obtained after inoculation of seeds on the one-year-old branches of Malus pumila var. dulcissima and Quercus mongolica trees. The technological aspects of the success can be applied to other host plants and provide a critical clue to an artificial propagation system, for this medicinally valuable genus. This is the first successful report on artificial inoculation and plant development of Korean mistletoe.

• The Plant Pathology Journal
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• 제35권1호
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• pp.19-31
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• 2019

Bud rot (BR) is the most devastating disease affecting oil palm (Elaeis guineensis) crops in Colombia. Its causal agent, Phytophthora palmivora, initiates the infection in immature oil palm leaflets producing necrotic lesions, followed by colonization of opportunistic necrotrophs, which increases disease damage. To improve the characterization of the disease, we transformed P. palmivora using Agrobacterium tumefaciens-mediated transformation (ATMT) to include the fluorescent proteins CFP-SKL (peroxisomal localization), eGFP and mRFP1 (cytoplasmic localization). The stability of some transformants was confirmed by Southern blot analysis and single zoospore cultures; additionally, virulence and in vitro growth were compared to the wild-type isolate to select transformants with the greatest resemblance to the WT isolate. GFP-tagged P. palmivora was useful to identify all of the infective structures that are commonly formed by hemibiotrophic oomycetes, including apoplastic colonization and haustorium formation. Finally, we detected cell death responses associated with immature oil palm tissues that showed reduced susceptibility to P. palmivora infection, indicating that these tissues could exhibit age-related resistance. The aim of this research is to improve the characterization of the initial disease stages and generate cell biology tools that may be useful for developing methodologies for early identification of oil palm materials resistant or susceptible to BR.

• The Plant Pathology Journal
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• 제20권2호
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• pp.81-84
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• 2004

Branched broomrape (Orobanche ramosa) is a holo-parasitic flowering plant that attaches to the root of its host, green plant, by means of a specialized structure known as haustorium. Following successful contact and penetration on susceptible plant root, complex tissue of Orobanche cells is formed which is known as the tubercle. Newly formed tubercles contain high activity ofindole-3-acetic acid (IAA). Triiodobenzoic acid (TIBA), as an inhibitor of IAA polar transport, was utilized to investigate the supply and requirement of auxin to the developing O. ramosa on tomato plant. There was no significant reduction in the incidence of O. ramosa per pot of different TIBA treatments. However, infection severity in terms of the number of O. ramosa shoots that emerged per plant and number of attachments per plant root system were significantly reduced by 60 % and 45 % on TIBA treated plants, respectively. Histo-logical studies revealed conspicuous delay in the initiation of xylem vessel differentiation inside tubercles of the TIBA treated tomato plants. Also, differentiated vessels showed thinner secondary wall deposition, and improper alignment within bundles inside those tubercles. They were wider and shorter in diameter in comparison to those of untreated plants. These findings were attri-buted to the short supply of IAA required for normal development, and to the xylem vessel differentiation of O. ramosa tubercles on infected tomato. Hence, this parasitic flowering plant seems to depend upon its host in its requirements for IAA, in a source to sink relation-ship.