• Title/Summary/Keyword: Immature seed

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Embryo Rescue Efficiency Affected by Developmental Stages of Embryo and Medium Composition in Early-Ripening Peach (Prunus persica)

  • Sewon Oh;Byeonghyeon Yun;Se Hee Kim;Sang-Yun Cho;Namhee Jung;Kyung Ran Do;Kang Hee Cho;Hyun Ran Kim
    • Korean Journal of Plant Resources
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    • v.37 no.3
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    • pp.263-269
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    • 2024
  • Embryos of early-ripening peaches could not achieve physiological maturation or undergo abortion before harvest. Embryo rescue is an effective strategy to rescue embryos from early-ripening peaches. Thus, the current study was carried out to determine the appropriate developmental stage and optimal medium composition for embryo rescue in early-ripening peach. Development of open-pollinated 'Yumi' fruit was investigated from 20 to 90 days after full bloom (DAFB) to explore period occurring endocarp hardening. After endocarp hardening, embryo development was observed by light microscopes. Shoot and root meristems were observed at 65 DAFB and embryo size rapidly increased at 75 DAFB. Embryos collected at 75, 80, 85, and 90 DAFB were cultured on four media based on Driver and Kuniyuki (DKW) medium. Germination rate of embryos cultured on four media gradually increased from 75 to 90 DAFB and reached 100% at 90 DAFB. Notably, M3 medium (0.5 DKW supplemented with 6-benzylaminopurine (BAP) 1.0 ㎎/L) displayed the highest germination rate at 75 and 80 DAFB stages. Growth and development of shoot and root were pronounced in plantlet cultured at 90 DAFB stage. While delayed shoot growth was evident in plantlets cultured at 75, 80, and 85 DAFB stages, this retardation could be overcome through the application of growth regulators, particularly in M3 and M4 (0.5 DKW supplemented with BAP 1.0 ㎎/L and indole-3-butyric acid 0.5 ㎎/L) media. Remarkably, roots of plantlet grown in M4 medium exhibited limited elongation. In conclusion, germination rate of embryo and growth of embryo cultured plantlet can be enhanced by collecting seeds from early-ripening 'Yumi' at the 90 DAFB stage and conducting embryo culture using the M3 medium.

Characterization of Oszinc626, knock-out in zinc finger RING-H2 protein gene, in Ac/Ds mutant lines of rice(Oryza sativar L.) (Zinc finger RING-H2 protein관련 Ac/Ds전이인자 삽입 변이체 Oszinc626 유전자의 특성 분석)

  • Park, Seul-Ah;Jung, Yu-Jin;Ahn, Byung-Ohg;Yun, Doh-Won;Ji, Hyeon-So;Park, Yong-Hwan;Eun, Moo-Young;Suh, Seok-Cheol;Lee, Soon-Youl;Lee, Myung-Chul
    • Journal of Plant Biotechnology
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    • v.35 no.3
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    • pp.177-183
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    • 2008
  • Ac/Ds mutant lines of this study were transgenic rice plants, each of which harbored the maize transposable element Ds together with a GUS coding sequence under the control of a promoterless(Ds-GUS). We selected the mutants that were GUS expressed lines, because the GUS positive lines will be useful for identifying gene function in rice. One of these mutants was identified knock-out at Oszinc626(NP_001049991) gene, encoding a RING-H2 zinc-finger protein, by Ds insertion. In this mutant, while primary root development is normal, secondary root development from lateral root was very poor and seed development was incomplete compare with normal plant. RING zinc-finger proteins play important roles in the regulation of development in a variety of organisms. In the plant kingdom, a few genes encoding RING zinc-finger proteins have been documented with visible effects on plant growth and development. The consensus of the RING-H2(C3-H2-C3 type) domain for this group of protein is $Cys-X_2-Cys-X_{28}-Cys-X-His-X_2-His-X_2-Cys-X_{14}-Cys-X_2-Cys$. Oszinc626 encodes a predicted protein product of 445 amino acids residues with a molecular mass of 49 kDa, with a RING-zinc-finger motif located at the extreme end of the C-terminus. RT-PCR analysis indicated that the expression of Oszinc626 gene was induced by IAA, cold, dehydration, high-salinity and abscisic acid, but not by 2,4-D, and the transcription of Oszinc626 gene accumulated primarily in rice immature seeds, root meristem and shoots. The gene accumulation patterns were corresponded with GUS expression.

The Concentration of Economic Power in Korea (경제력집중(經濟力集中) : 기본시각(基本視角)과 정책방향(政策方向))

  • Lee, Kyu-uck
    • KDI Journal of Economic Policy
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    • v.12 no.1
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    • pp.31-68
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    • 1990
  • The concentration of economic power takes the form of one or a few firms controlling a substantial portion of the economic resources and means in a certain economic area. At the same time, to the extent that these firms are owned by a few individuals, resource allocation can be manipulated by them rather than by the impersonal market mechanism. This will impair allocative efficiency, run counter to a decentralized market system and hamper the equitable distribution of wealth. Viewed from the historical evolution of Western capitalism in general, the concentration of economic power is a paradox in that it is a product of the free market system itself. The economic principle of natural discrimination works so that a few big firms preempt scarce resources and market opportunities. Prominent historical examples include trusts in America, Konzern in Germany and Zaibatsu in Japan in the early twentieth century. In other words, the concentration of economic power is the outcome as well as the antithesis of free competition. As long as judgment of the economic system at large depends upon the value systems of individuals, therefore, the issue of how to evaluate the concentration of economic power will inevitably be tinged with ideology. We have witnessed several different approaches to this problem such as communism, fascism and revised capitalism, and the last one seems to be the only surviving alternative. The concentration of economic power in Korea can be summarily represented by the "jaebol," namely, the conglomerate business group, the majority of whose member firms are monopolistic or oligopolistic in their respective markets and are owned by particular individuals. The jaebol has many dimensions in its size, but to sketch its magnitude, the share of the jaebol in the manufacturing sector reached 37.3% in shipment and 17.6% in employment as of 1989. The concentration of economic power can be ascribed to a number of causes. In the early stages of economic development, when the market system is immature, entrepreneurship must fill the gap inherent in the market in addition to performing its customary managerial function. Entrepreneurship of this sort is a scarce resource and becomes even more valuable as the target rate of economic growth gets higher. Entrepreneurship can neither be readily obtained in the market nor exhausted despite repeated use. Because of these peculiarities, economic power is bound to be concentrated in the hands of a few entrepreneurs and their business groups. It goes without saying, however, that the issue of whether the full exercise of money-making entrepreneurship is compatible with social mores is a different matter entirely. The rapidity of the concentration of economic power can also be traced to the diversification of business groups. The transplantation of advanced technology oriented toward mass production tends to saturate the small domestic market quite early and allows a firm to expand into new markets by making use of excess capacity and of monopoly profits. One of the reasons why the jaebol issue has become so acute in Korea lies in the nature of the government-business relationship. The Korean government has set economic development as its foremost national goal and, since then, has intervened profoundly in the private sector. Since most strategic industries promoted by the government required a huge capacity in technology, capital and manpower, big firms were favored over smaller firms, and the benefits of industrial policy naturally accrued to large business groups. The concentration of economic power which occured along the way was, therefore, not necessarily a product of the market system. At the same time, the concentration of ownership in business groups has been left largely intact as they have customarily met capital requirements by means of debt. The real advantage enjoyed by large business groups lies in synergy due to multiplant and multiproduct production. Even these effects, however, cannot always be considered socially optimal, as they offer disadvantages to other independent firms-for example, by foreclosing their markets. Moreover their fictitious or artificial advantages only aggravate the popular perception that most business groups have accumulated their wealth at the expense of the general public and under the behest of the government. Since Korea stands now at the threshold of establishing a full-fledged market economy along with political democracy, the phenomenon called the concentration of economic power must be correctly understood and the roles of business groups must be accordingly redefined. In doing so, we would do better to take a closer look at Japan which has experienced a demise of family-controlled Zaibatsu and a success with business groups(Kigyoshudan) whose ownership is dispersed among many firms and ultimately among the general public. The Japanese case cannot be an ideal model, but at least it gives us a good point of departure in that the issue of ownership is at the heart of the matter. In setting the basic direction of public policy aimed at controlling the concentration of economic power, one must harmonize efficiency and equity. Firm size in itself is not a problem, if it is dictated by efficiency considerations and if the firm behaves competitively in the market. As long as entrepreneurship is required for continuous economic growth and there is a discrepancy in entrepreneurial capacity among individuals, a concentration of economic power is bound to take place to some degree. Hence, the most effective way of reducing the inefficiency of business groups may be to impose competitive pressure on their activities. Concurrently, unless the concentration of ownership in business groups is scaled down, the seed of social discontent will still remain. Nevertheless, the dispersion of ownership requires a number of preconditions and, consequently, we must make consistent, long-term efforts on many fronts. We can suggest a long list of policy measures specifically designed to control the concentration of economic power. Whatever the policy may be, however, its intended effects will not be fully realized unless business groups abide by the moral code expected of socially responsible entrepreneurs. This is especially true, since the root of the problem of the excessive concentration of economic power lies outside the issue of efficiency, in problems concerning distribution, equity, and social justice.

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