• Molecules and Cells
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• v.26 no.6
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• pp.611-615
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• 2008

DNA methylation is an epigenetic mechanism for gene silencing. In Arabidopsis, MET1 is the primary DNA methyltransferase that maintains CG DNA methylation. Plants having an overall reduction of MET1 activity, caused by a met1 mutation or a constitutively expressed MET1 antisense gene, display genome hypomethylation, inappropriate gene and transposon transcription, and developmental abnormalities. However, the effect of a transient reduction in MET1 activity caused by inhibiting MET1 expression in a restricted set of cells is not known. For this reason, we generated transgenic plants with a MET1 antisense gene fused to the DEMETER (DME) promoter (DME:MET1 a/s). Here we show that DME is expressed in leaf primordia, lateral root primoridia, in the region distal to the primary root apical meristem, which are regions that include proliferating cells. Endogenous MET1 expression was normal in organs where the DME:MET1 a/s was not expressed. Although DME promoter is active only in a small set of cells, these plants displayed global developmental abnormalities. Moreover, centromeric repeats were hypomethylated. The developmental defects were accumulated by the generations. Thus, not maintaining CG methylation in a small population of proliferating cells flanking the meristems causes global developmental and epigenetic abnormalities that cannot be rescued by restoring MET1 activity. These results suggest that during plant development there is little or no short-term molecular memory for reestablishing certain patterns of CG methylation that are maintained by MET1. Thus, continuous MET1 activity in dividing cells is essential for proper patterns of CG DNA methylation and development.

• Journal of Plant Biotechnology
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• v.30 no.1
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• pp.109-113
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• 2003

Cryopreservation of embryogenic callus derived from apical meristem culture was attempted by slow prefreezing method (two-step method) with various cryoprotectants in sweetpotato cv. 'Yulmi' Precultured embryogenic calli on medium containing 10 mg/L ABA prior to slow prefreezing in liquid nitrogen indicated higher survival rate than 1.0 mg/L ABA preteatment. The cryoprotectant comprising 1.28 M DMSO in 0.4 M sucrose solution gave the best survival (over 46%) of sweetpotato cells exposed to liquid nitrogen as determined by TTC reduction and FDA staining method. Cryopreserved calli cultured on MS medium with 1.0 mg/L 2,4-D were grown for 4 weeks in the dark and induced embryos after another 4 weeks. They were subcultured on MS medium supplemented with 0.1 mg/L 2,4-D＋0.1 mg/L kinetin for 2 weeks and regenerated into normal plantlets in MS basal medium.

• Korean Journal of Plant Tissue Culture
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• v.25 no.5
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• pp.329-333
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• 1998

$\beta$-Glucuronidase (GUS) gene of Escherichia coli was introduced into sweet potato (Ipomoea batatas (L.) Lam.) cells by particle bombardment and expressed in the regenerated plants. Microprojectiles coated with DNA of a binary vector pBI121 carrying CaMV35S promoter-GUS gene fusion and a neomycin phosphotransferase gene as selection marker were bombarded on embryogenic calli which originated from shoot apical meristem-derived callus and transferred to Murashige and Skoog (MS) medium supplemented with 1 mg/L 2,4-dichlorophenoxyacetic acid and 100 mg/L kanamycin. Bombarded calli were subcultured at 4 week intervals for six months. Kanamycin-resistant calli transferred to MS medium supplemented with 0.03 mg/L 2iP, 0.03 mg/L ABA, and 50 mg/L kanamycin gave rise to somatic embryos. Upon transfer to MS basal medium without kanamycin, they developed into plantlets. PCR and northern analyses of six regenerants transplanted to potting soil confirmed that the GUS gene was inserted into the genome of the six regenerated plants. A histochemical assay revealed that the GUS gene was preferentially expressed in the vascular bundle and the epidermal layer of leaf, petiole, and tuberous root.

• Korean Journal of Medicinal Crop Science
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• v.5 no.1
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• pp.36-42
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• 1997

This study was investigated on the effects of colchicine and EMS. induced mutation, plant on the germination and polypeptide pattern and peroxidase activity monitored by two dimensional gel analysis in Wasabia japonica Matsum (wasabi). Germination rate of Muju was higher than that of Ulrung-Do and optimum concentration for germination was appeared 100 ppm GA3 containing with 10 ppm BAP in these cultivars. Survived plants rate of Muju was higher than that of Ulrung-Do after colchicine and EMS treatment. Peroxidase activity and plant height were decreased by mutagen treatments, while incresed in root and stem thickness. The number of protein spots and pattern showed difference between Muju and Ulrung-Do . The plants treated mutagen increased polypeptide spots, especially EMS treatment showed more different polypeptide pattern compared to control.

• Journal of Bio-Environment Control
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• v.15 no.2
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• pp.190-195
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• 2006

The purpose of this study was to figure out the best condition in growth and sod quality of Mentha spp. according to cutting methods and soil depth. Applemint (M. suaveolens), Peppermint (M. piperita), and Spearmint (M. spicata) were used. Regardless of cultivar and soil depth condition, the growth rate in top cutting was higher than layering method. The difference between layering and layering without apical meristem was not significant. Optimal condition for growth was 5cm depth of soil. However, the shallower the depth of the soil, the better quality of sod. Among three Mentha species, M suavelens showed plant height and node number and M. piperita had shoot number were higher than other variety. The best condition of sod was top cutting and 1cm depth of soil regardless of cultivar.

• Journal of Plant Biology
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• v.35 no.3
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• pp.211-217
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• 1992

In order to elucidate the formation of reaction tissues during the transition from primary to secondary growth, the developmental anatomy was conducted in the first internode of Acer sacchan'num seedling in horizontal position. During the transition from primary to secondary growth, tension wood(gelatinous fiber) was gradually developed on the upper side only, And the tension wood formation in the upper side of the horizontal first internode proceeds acropetally from base to apical portion. Some of the anatomical features of tension wood start to be in the primary vascular tissue and a typical tension wood show during the secondary growth, Therefore, the procambium seems to respond to the gravity as well as vascular cambium. For this reason, both procambium and vascular cambium has to regard as the same meristem, On the other hand, the upper side vessels were longer than those of the lower side in the horizontal first internode. The lateral-wall pitting of vessel elements, however, showed no differences between upper and lower sides which have alternate type. The width and height of rayon the upper side of horizontal first internode was larger as compared with the lower side.r side.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.51-56
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• 1999

Plastids, which are organelles unique to plant cells, bear their own genome that is organized into DNA-protein complexes (nucleoids). Regulation of gene expression in the plastid has been extensively investigated because this organelle plays an important role in photosynthesis. Few attempts, however, have been made to characterize the regulation of plastid gene expression at the chromosomal structure, using plastid nucleoids. In this report, we summarize the recent progress in the characterization of DNA-binding proteins in plastids, with special emphasis on CND41, a DNA binding protein, which we recently identified in the choloroplast nucleoids from photomixotrophically cultured tobacco cells. CND41 is a protein of 502 amino acids which consisted of a transit peptide of 120 amino acids and a mature protein of 382 amino acids. The N-terminal of the 'mature' protein has lysine-rich region which is essential for DNA-binding. CNA41 also showed significant identities to some aspartyl proteases. Protease activity of purified CND41 has been recently confirmed and characterized. On the other hand, characterization of accumulation of CND41 both in wild type and transgenic tobacco with reduced amount of CND41 suggests that CND41 is a negative regulator in chloroplast gene expression. Further investigation indicated that gene expression of CND41 is cell-specifically and developmentally regulated as well as sugar-induced expression. The reduction of CND41 expression in transgenic tobacco also brought the stunted plant growth due to the reduced cell length in stem. GA3 treatment on apical meristem reversed the dwarf phenotype in the transformants. Effects of CND41 expression on GA biosynthesis will be discussed.

• Korean Journal of Weed Science
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• v.15 no.3
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• pp.206-213
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• 1995

Glyphosate(N-[phosphonomethyl]glycine) applied to the assimilate-exporting leaves(i.e. third old leaf) of tomato(Lycopersicon esculentum Mil var. Moneymaker). Herbicide binding protein, QB protein(D1), has been immunoblotted using the antibodies raised against the hybrid-protein expressed by a part of spinach psb A gene cloned in frame with the 3'end of lac Z gene to allow expression of the ${\beta}$-galactosidase(EC 3.21.23) in Escherichia coli. Glyphosate has an effect on a turnover of D1 within photosystem II of thylakoid membrane. The dysfunction of D1 protein within light harvesting complex(LHC-II) seems to be a pleiotropic effect of glyphosate.

• Korean Journal of Plant Tissue Culture
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• v.26 no.2
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• pp.85-91
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• 1999

In sweet potato cultivars 'Mokpo #29' and 'Sanchunza', shoots from extplants were formed 100% on the MS medium with 0.1 ㎎/L NAA and 2.0 ㎎/L BA after 30 days of culture and roots produced from the base of stem at frequencies of 66.7% ('Mokpo #29') and 69.2% ('Sanchunza'), respectively, The media with 0.5∼4.0 ㎎/L BA were produced the greatest frequency of multiple shoot and the most of shoots developed rapidly into normal plantlets with rooting within 60 days of culture. Whereas the cultivar 'Keumsi' failed to produce normal shoot multiplication on the medium with cytokinins alone because of callusing of adventitious shoots. When single shoots with 1 to 2 nodes were excised from the multiple shoot or shoots covered with callus devoid of root and transferred to MS medium with 4.0 ㎎/L BA or kinetin. Host divided shoots showed the callus induction at the stem base and it was enable to obtain regenerated plantlets with shoot and root normally.

• Journal of Ginseng Research
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• v.11 no.2
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• pp.111-117
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• 1987

The phase and times on the development of dormancy bud in seedling, and those of flower organs in 2-year-old ginseng are different to those of over 2-,3-year-old plant, respectively. The growing aspects of dormancy bud in seedling were investigated from rooting stage (April, 8) to Mid-June, and those of flower organs in 2-year-old plant had done once in two days late in April after compound leaves were unfolded. Firstly, the formation of dormancy bud in seedling was begun on Mid-late in March. This is early about one month compare with those of over 2-year-old plant. Fine bud in seedling was formed between cotyledons, at W spot under young shoot. Secondly, development of flower organs in 2-year-old plant was completed from late of April to early of May after compound leaves of transplanted plant were unfolded. In tare, this is very different characteristics because plants of any other ages form the flower organs one year ago. Thirdly, flower organs of ginseng plant, over 3-year-old plant, always develop in the rhizome formed one year ago, but those of 2-year-old plant develop in apical shoot meristem.