• Journal of Plant Biotechnology
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• v.39 no.1
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• pp.69-74
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• 2012

Using calli of $Muscari$ $armeniacum$ cv. 'Early Giant' that is monocotyledonous ornamental bulb crop with increasing demand in Korea, we carried out current studies to establish an in vitro multiple propagation protocol via somatic embryogenesis. We found that soft pale yellow green calli were induced from leaf explants cultured on all media containing 0.1~3.0 $mg{\cdot}L^{-1}$ auxins such as 1-naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D). However, induced calli showed vigorous growth only when they further transferred on same media containing 2,4-D, 4-amino-3,5,6-tri-chloropicolinic acid (picloram), or 3,6-dichloro-o-anisic acid (dicamba). Although frequency of somatic embryo induction depended on callus source and PGR composition in somatic embryo induction media, somatic embryogenesis was initiated on surface of proliferated calli after transferring on media with no PGR or 0.01 $mg{\cdot}L^{-1}$ NAA co-supplemented with various cytokinins such as $N^6$-benzylaminopurine (BAP). Highest number of embryo at 9.3 per callus clump was obtained when calli which were grown under 0.1 $mg{\cdot}L^{-1}$ picloram supplementation were sub-cultured on medium with 0.01 $mg{\cdot}L^{-1}$ NAA and 0.5 $mg{\cdot}L^{-1}$ BAP. In addition, morphological characteristics of somatic embryo were categorized into following nine phases: globular, biased heart, biased torpedo, early cotyledonary, middle cotyledonary, late cotyledonary, early sprouting, middle sprouting, and late sprouting embryos.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.1
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• pp.22-26
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• 2014

This research was implemented to investigate pre-harvest sprouting characteristics in two Korean rice cultivars, Shindongjin (SDJ) and Hopum (HP). The panicles of both varieties were sampled after 15 days after heading (DAH) to 60 DAH at intervals of 5 days. As soon as sampled, the panicles were imbibed in water for 14 days at $25^{\circ}C$ to determine the vigor and germination ability of seeds according to location on panicle. To investigate the cause of non-germination of seeds in panicles, tetrazolium test and dormancy breaking were performed. The preharvest sprouting of HP started at 20 DAH while that of SDJ began at 30 DAH. The germination of seeds located in high rank branches within a panicle and the terminal seeds within a branch were earlier and faster and the germination patterns were same in both cultivars. The times at more than 50% of germination in a panicle were 35 DAH (57.0%) in HP and 45 DAH (56.8%) in SDJ. Preharvest sprouting was more than 80% at 50 DAH (82.6% of HP, 92.3% of SDJ) and more than 99% at 60 DAH (99.5%, 99.4%, HP and SDJ). These results indicated that the rate of PHS in a panicle increased with accumulation of the days after heading. The cause of non-germinated seeds at 15-25 DAH in panicle was immature embryo. After 30 DAH, however, when the non-germinated seeds were hulled, they started to germinate due to dormancy breaking, in which the germination percentage was higher in SDJ than HP. In conclusion, the pre-harvest sprouting varied according to days after heading, the seed position on panicle, and the dormancy intensity of varieties.

• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.157-157
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• 2023

Pre-harvest sprouting (PHS) in rice (Oryza sativa L.) is one of the main problems associated with seed dormancy. PHS causes yield loss and reduction of grain quality under unpredictable humid conditions at the ripening stage, thus affecting the economic value of the rice crop. To resolve this issue, it is important to understand the molecular mechanism underlying seed dormancy in rice. Recent studies have shown that seed dormancy is affected by a large number of genes associated with plant hormones. However, the effect of heat stress on seed dormancy and plant hormones is not well understood. In this study, we compared the PHS rate as well as the transcriptome and small RNAome of the seed embryo and endosperm of two different accessions of rice, PHS-susceptible rice (low dormancy) and PHS-resistant rice (high dormancy) under three different maturation stages. We identified and verified the candidate genes associated with seed dormancy and heat stress-related responses in rice using quantitative real-time PCR. We newly discovered hormone-related genes, heat shock protein-related genes, and miRNAs potentially involved in PHS. These findings provide a foundation for understanding the dynamics of transcriptome and small RNAome of hormone- and heat stress-related genes, which affect PHS during seed maturation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.427-434
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• 2014

This study aimed to investigate the effects of pre-harvest sprouting (PHS)-damaged grains of rice on seed viability, germination percentage and seedling emergence rate. As comparing the seed lots of same cultivar 'Hopum' with different PHS percentages, seed lot with 8% PHS (high PHS percentage) showed 30% lower germination than that with 1% PHS (low PHS percentage). The difference of seedling emergence rate and seed viability percentages between the two seed lots was consistent with that of germination percentage. PHS-damaged brown rice was observed protruded embryo, discolored endosperm and fungi infected grains. PHS grains were classified into two groups, PHS-I showing endosperm discoloration in one third of a grain and PHS-II in more than half of a grain. The seed lot with high PHS percentage had much more PHS-II grains than that of low PHS percentage. PHS-II grains showed remarkably lower germination percentage than PHS-I grains and got severely moldy during germination test. In laboratory experiment, morphological changes and re-germination ability of seeds which dried after germination by soaking were tested. Sprouted seeds of 3mm shoot length showed half discolored endosperm and had a strong resemblance with PHS-II grains. Re-germination percentage of 3mm sprouted seeds sharply decreased than 2 mm sprouted seeds. Sprouted seeds which were treated for accelerated-aging (AA) for 24hr at $45^{\circ}C$ were significantly reduced in re-germination percentage compared to that of non-AA-treated sprouted seeds. These results indicate that PHS with over 3mm shoot length can severely damage not only grain appearance but also seed viability, germination percentage and seedling emergence rate. Therefore, we conclude that larger difference of germination percentage or seedling emergence rate between seed lots having smaller difference of PHS percentage might be caused by accelerated seed deterioration in PHS-damaged rice grains.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2000.10a
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• pp.114-115
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• 2000

Aralia elata is found in mountain areas all over Korean peninsula. Aralia elata is the scientific name for Japanese angelica tree. The tree belongs to the family Araliaceae, commonly known as ginseng family. Bud sprouts from apical shoot tip of the plants are rich in flavor and thus mainly used for both folk medicine and vegetable. The stalks with apical buds are gathered in the early spring and planted in sandy soil or water in the greenhouse. The sprouting buds are then collected and sold as fresh vegetable. Although the plants have been used for food, they have been cultivated in a very small scale. In spring, local farmers just go around mountain areas to search the trees and gather the stalks as much as they get and sell them to the market. No conservation efforts have been made to stop the exploitation or to save the dwindling population. We tried to provide local farmers with the plants that may be used as an alternative to stalks from wild populations. This will bel! p conserve the wild populations. However, it is hard to propagate them either by conventional cuttings or by seed germination in a short period of time. Mass propagation using tissue culture systems have shown a great promise with several woody plants. Recently we developed a mass propagation technique via somatic embryogenesis system using mature and/or juvenile explants for Aralia elata. Several factors affecting somatic embryogenesis system including SE(somatic embryo) induction, embryogenic callus proliferation, SE germination, plant regeneration and transplanting to field frill be presented. And some problems arising for the somatic embryogenesis system will be also discussed.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2000.10b
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• pp.16-17
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• 2000

Aralia elata is found in mountain areas all over Korean peninsula. Aralia elata is the scientific name for Japanese angelica tree. The tree belongs to the family Araliaceae, commonly known as ginseng family. Bud sprouts from apical shoot tip of the plants are rich in flavor and thus mainly used for both folk medicine and vegetable. The stalks with apical buds are gathered in the early spring and planted in sandy soil or water in the greenhouse. The sprouting buds are then collected and sold as fresh vegetable. Although the plants have been used for food, they have been cultivated in a very small scale. In spring, local farmers just go around mountain areas to search the trees and gather the stalks as much as they get and sell them to the market. No conservation efforts have been made to stop the exploitation or to save the dwindling population. We tried to provide local farmers with the plants that may be used as an alternative to stalks from wild populations. This will hel! p conserve the wild populations. However, it is hard to propagate them either by conventional cuttings or by seed germination in a short period of time. Mass propagation using tissue culture systems have shown a great promise with several woody plants. Recently we developed a mass propagation technique via somatic embryogenesis system using mature and/ or juvenile explants for Aralia elata. Several factors affecting somatic embryogenesis system including SE(somatic embryo) induction, embryogenic callus proliferation, SE germination, plant regeneration and transplanting to field will be presented. And some problems arising for the somatic embryogenesis system will be also discussed.lso discussed.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.5
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• pp.533-538
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• 2016

Angiogenesis plays an essential role in embryo development, tissue repair, inflammatory diseases, and tumor growth. In the present study, we showed that endothelial nitric oxide synthase (eNOS) regulates retinal angiogenesis. Mice that lack eNOS showed growth retardation, and retinal vessel development was significantly delayed. In addition, the number of tip cells and filopodia length were significantly reduced in mice lacking eNOS. Retinal endothelial cell proliferation was significantly blocked in mice lacking eNOS, and EMG-2-induced endothelial cell sprouting was significantly reduced in aortic vessels isolated from eNOS-deficient mice. Finally, pericyte recruitment to endothelial cells and vascular smooth muscle cell coverage to blood vessels were attenuated in mice lacking eNOS. Taken together, we suggest that the endothelial cell function and blood vessel maturation are regulated by eNOS during retinal angiogenesis.