• Journal of Plant Biology
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• v.37 no.2
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• pp.159-166
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• 1994

Direct current (DC) applied to cotyledons during a 16 h inductive dark period inhibited the flowering in the short-day plant, Pharbitis nil Choisy cv. Violet. The inhibitory effect of DC was more profound when the current flowed from roots to cotyledons, showing its polarity-dependent action. The second half on the inductive dark period was more sensitive to DC stimulus. The flowering was significantly depressed only when DC stimuli were applied to the translocation path of the floral stimulus from the induced cotyledon to the apex, suggesting that the transport of floral stimulus was damaged by the DC treatment. The vegetative apex culture bioassay system showed that a significant level of the floral stimulus activity existed in the phloem exudate from the cotyledons which would fail to form their own floral buds. These results strongly support the hypothesis that DC partially impede, at least temporarily, the transmission path of the floral stimulus from florally-induced cotyledon to the apex, rather than depressing in situ synthesis of the floral stimulus.

• Journal of Korean Society of Forest Science
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• v.94 no.2 s.159
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• pp.67-72
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• 2005

The objectives of this study were to identify the period of initiation of floral primordia in black locust (Robinia pseudoacacia L.) and subsequent development of floral buds until following spring. Four mature trees of black locust located in Suwon, Korea were selected. Bud samples were collected from the current-year shoots, starting from mid June to July every week, from August to October and from February to April every month. The buds were fixed in FAA solution, dehydrated, and imbedded in paraffin for microscopic observation. Buds collected on June 16, and 23, 1997, contained primitive primordia that might be interpreted as early floral primordia. By June 30, a bud showed a positive indication of inflorescence primordium with a well-formed shoot apex. All the inflorescence primordia observed throughout the collection periods were always associated with unique hairy appendages around the primordium and enclosed within a sclerenchymatous chamber. By July 7 and 15, a floral apex had early bud scales. By July 22, primitive inflorescence developed into visible arrangement of individual floral primordial By July 29, the inflorescence developed into whirl arrangement of individual floral primordia in a transverse section, but showed little further development until October 15. The inflorescence primordia seemed to over-winter at this stage. Buds collected from February 15 and March 24 the following year also showed no further development of inflorescence primordia. By April 7 the inflorescence started to show further development with elongated axis. At this time individual flowers were easily recognized.

• Korean Journal of Plant Taxonomy
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• v.48 no.3
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• pp.172-184
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• 2018

We examined the floral morphology of 15 taxa of five genera (Cynanchum, Marsdenia, Metaplexis, Tylophora, and Vincetoxicum) in Korean Asclepiadoideae using a stereoscopic and scanning electronic microscope to clarify and describe the floral characteristics. In this study, the corolla and corona types, the types of corona lobes, appendages on the corona lobes, and the apex shape of the style head are considered as diagnostic characteristics at the generic level. The genus Vincetoxicum, which is treated as a synonym of the genus Cynanchum in Korea, is distinguished from Cynanchum by the interstaminal part on the corona, fleshy and mainly triangular or ellipsoid corona lobes, and various corolla colors. In Cynanchum, various corona types have been observed, while Vincetoxicum have similar corona types among the taxa. In addition, the main floral characteristics at the species level were as follows: flowering time, inflorescence, corolla color, trichomes on the corolla surfaces, apex shape of the corona lobe, and trichomes on the ovary. This study presents the taxonomic importance of floral morphology by providing descriptions and diagnostic characteristics among the genera and species investigated.

• Korean Journal of Medicinal Crop Science
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• v.11 no.2
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• pp.122-126
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• 2003

This study was conducted to investigate plant growth characteristics and anatomical studies of Korean mistel (Viscum album var. coloratum (Kom.) Ohwi). Parasite position was upper part that has a plenty of sunshine area 5 to 10m apart from the ground, regardless host tree. Stem developed two branch stems from the each basal stem, leaf was grown from the end stems as opposite. Fruit has a light yellow color and berry size was 7 to 8 mm long diameter and it contains seed. Floral bud differentiation initiated with forming rounded dome and arch-shaped floral apex at the beginning stage, and produced heart-shaped sepal following the differentiation of leaf primordia. Floral bud formation processed centeral part first and following bilateral sides were developed in order. Leaf was thick and stoma and guard cell were observed from the two or three inner layers from the epidermis. Mistletoe penetrated cork cambium of host plant and was growing by rooting on xylem. Korean mistel connected to host plant through parasitic organ, haustorium structurally and physiologically.

• Journal of Photoscience
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• v.7 no.3
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• pp.103-108
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• 2000

We have evaluated a new mutagenesis strategy called random insertional mutagenesis with subtracted cDNA fragments. The cDNAs from long day Arabidopsis plants were subtracted by cDNAs from short day plants using PCR based cDNA subtraction. The subtracted cDNAs were inserted between 35S promoter and 3'-NOS terminator regardless of orientation. When the cDNA library was used for the random insertion into Arabidopsis genome by Agrobacterium-mediated transformation, approximately 15% of transformants showed abnormal development in leaf, floral organ, shoot apex. When 20 mutants were analyzed, 12 mutants showed single cDNA fragment insertion and 8 mutants showed more than 2 transgene insertions. Only two mutants among 12 mutants that have single cDNA insert showed consistent phenotype at T2 generation, suggesting the genetic instability of the mutants.

• Proceedings of the Botanical Society of Korea Conference
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• 1996.07a
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• pp.4-9
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• 1996

The majority of plants sense environmental signals, such as day length or temperature, to select their transition timing from vegetative growth t flowering. Here, we report the identification of a regulatory gene, OsMADS1, that controls the photoperiod sensitivity of flowering time. Constitutive expression of OsMADS1 in a long-day flowering plant, Nicotiana sylvestris, resulted in flowering in both short-day long-day conditions. Similarly, ectopic expression of the gene in a short-day flowering plant, N. tabacum cv. Maryland Mammoth, also induced flowering regardless of the day length. The transition time was dependent on the level of the OsMADS1 transcript in transgenic plants. These suggest that OsMADS1 is a key regulatory factor that determines the transition from shoot apex to floral meristem and that it can be used for controlling flowering time in a variety of plant species.

• Korean Journal of Plant Taxonomy
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• v.52 no.3
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• pp.144-155
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• 2022

Daphne kiusiana is an evergreen shrub with dense head-like umbels of white flowers distributed in southern Korea, Japan, China, and Taiwan. Plants in China and Taiwan are recognized as var. atrocaulis by having a dark purple stem, elliptic leaves, and persistent bracts. Recently, plants on Jejudo Island were segregated as a separate species, D. jejudoensis, given their elliptic leaves with an acuminate apex, a long hypanthium and sepals, and a glabrous hypanthium. Morphological variations of three closely related taxa, the D. kiusiana complex, were investigated across the distributional range to clarify the taxonomic delimitation of members of the complex. Twelve characters of the leaf and flower were measured from digitized herbarium specimens using the image analysis program ImageJ and were included in a morphometric analysis, the results of which indicate that the level of variation in the characters is very high. The results of a principal component analysis weakly separated D. jejudoensis from D. kiusiana according to their floral characteristics, such as a longer, glabrous hypanthium, and larger sepals. However, some individuals of D. kiusiana, particularly those from Bigeumdo Island, were included in D. jejudoensis. Recognition of D. kiusiana var. atrocaulis based on the leaf shape was not supported in the analysis, and D. jejudoensis may be recognized as a variety of D. kiusiana. Our morphometric analysis shows that digitized images of herbarium specimens could be useful and an additional method by which to investigate more diverse specimens.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.540-545
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• 2006

T-DNA-mediated transformation is a common method for generating transgenic plants with insertional mutagenesis. In order to identify important genes involved in shoot development, a system of promoter trap insertional mutagenesis was employed in Arabidopsis thaliana. For this system, an efficient promoter trap vector, pFGL561 was developed. The pFGL561 includes a basta-resistant gene, an intron with multiple splicing donor and acceptor sites, and a promoter-less GFP reporter gene. Using floral-dipping method, we made total 300 $T_1$ promoter-trap lines which were screened for GFP expression. GFP signals in the $T_1$ plants were detected with high frequency, 26.7%, and the signals were reconfirmed in $T_2$ plants. To isolate the genes that are involved in shoot development, phenotypes were analyzed in $T_2$ plants of the 19 $T_1$ lines that had GFP signals in shoot apex, and 6 $T_1$ lines were selected that had abnormal shoot development. These lines will be very useful for the investigation of shoot development.