• Horticultural Science & Technology
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• v.32 no.3
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• pp.382-389
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• 2014

Raphanus sativus L. cv. Taebaek, a efficiently microspore-derived embryo (MDE)-forming cultivar, and 'Chungwoon', a non-MDE-forming cultivar were selected as donor plants for isolated microspore culture. Radish flower bud of 2.0 (small, S), 4.0 (medium, M), and 6.0 (large, L) ${\pm}$ 0.5 mm in length were isolated to determine the temporal relationship between flower bud size and MED yield. Anatomical observations revealed no difference in the structure of the flower buds between the two cultivars. In both cultivars, the stigmas were much longer than the floral leaf in M-sized flower buds. The MDE yields for 'Taebaek' per petri dish were 6.6 and 1.3 for M- and L-sized of flower buds, respectively, but MDE formation was not induced in the S flower buds. On the other hand, 'Chungwoon' failed to form MDEs in all flower buds. The microspore density of 'Taebaek' was 1.3 times more than that of 'Chungwoon' for M sized flower buds. Of the M-sized buds from 'Taebaek' and 'Chungwoon', 92.1 and 81.6%, respectively, were in the late uninucleate microspore stage, which is characterized by the highest frequency of MDE formation. Anatomical observations of MDE formation revealed that the microspores were able to divide to form a primordium from which cell division took place continuously in the 'Teabeak' cultivar. However, the microspores of 'Chungwoon' failed to progress beyond the primodium stage, resulting in lack of MDE formation. By contrast, after the formation of the primordium, various developmental stages of embyos from microspore were observed in the 'Taebaek' cultivar. These results can be used to determine MDE forming potentials of radish cultivars.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.394-406
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• 1991

It was proved that cold tolerance of rice plants at the young microspore stage was affected by water temperature and nitrogen application from the spikelet differentiation stage to the young microspore stage, and this mechanism could be explained in the point of view of pollen developmental physiology. The cold tolerance of rice plants at the young microspore stage was severely affected by water temperature (Previous water temperature) and nitrogen application(Previous nitrogen application) from the spikelet differentiation stage to the spikelet differentiation stage. Although the duration is only 10 days or so from the spikelet differentiation stage to the young microspore stage, these days are very important period to confirm the cold tolerance of rice plants at the young microspore stage. The higher previous water temperature up to $25^{\circ}C$ and the deeper previous water depth up to 10cm caused the more cold tolerance of rice plants. Water irrigation of 10cm before the cretical stage showed lower cool injury than that of water irrigation of 20cm during the critical stage. The preventive effect of cool injury by combined treatment of the deep water irrigation before and during the critical stage was not additive but synergistic. The cold tolerance of rice plants grown in previous heavy nitrogen level was rapidly decreased when nitrogen content of leaf blade at the young microspore stage was excessive over the critical nitrogen level. Nitrogen content of leaf blade at the changing point of cold tolerance was estimated as about 3.5% for Japonica cultivars and about 2.5% for Indica x Japonica cultuvars. It is considered that these critical nitrogen contents of leaf blade can be used as a index of the safe critical nitrogen level for the preventive practices to cool injury. It was summarized that increase of engorged pollens per anther by high previous water temperature resulted from the increase of number of differentiated microspores per anther, otherwise, the increase of engorged pollens by the decrease of previous nitrogen level was caused by the decrease of the number of aborted microspores per anther.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.66-72
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• 2006

Spikelet proteins expressed at the young microspore stage in rice were separated and analysed by two-dimensional polyacrylamide gel electrophoresis (2DE). The separated proteins were electro blotted onto a polyvinylidene difluoride (PVDF) membrane, and 50 proteins were analyzed by a gas-phase protein sequencer. The N-terminal amino acid sequences of 20 out of 50 proteins were determined. N-terminal regions of the remaining proteins could not be sequenced because of blocking. The internal amino acid sequences of proteins were determined by sequence analysis of peptides obtained by the Cleveland peptide mapping method. Results revealed the presence of the photosynthetic apparatus at rice young microspore stage. Major proteins identified in this study could be used as a marker for various studies on physiological stresses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.1
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• pp.62-67
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• 2002

An efficient system of rice microspore culture could contribute to the production of genetically modified rice. The microspores were isolated by mechanical or shed methods. The number of microspores per 100 anthers isolated at uninucleate stage was higher than (or similar to) those at binucleate stage in isolation method with pestle or spatular, but microspore divisions were not easily observed on both stages. On the other hand, pollen division in shed pollen culture was observed more frequently at uninuclear than at binuclear stage. Cold pretreatment at 1$0^{\circ}C$ for 10 days resulted in the best multicellular division to produce microcalli at 12.5% efficiency in shed microspores. Heat shock at 33$^{\circ}C$ for one hour before or after pollen shedding enhanced cell division and callus formation. Out of twelve green regenerants, two were haploids and ten were diploids based on the chromosome analysis of root tips. The size of stoma was 12$^{m}$ m in haploids and 15 ${\mu}{\textrm}{m}$ in diploids determined by scanning electron microscope (SEM).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.242-246
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• 2006

This study was showed into the pollen development with in vivo by bud size and genotype. Microspores of buds from 2.0 mm to 2.5 mm of all genotypes were composed of mainly tetrad cells and early uninucleate stage cells. Microspores derived from buds of 2.5-3.0 mm were exposed cells of early uninucleate, middle uninucleate, and late uninucleate. Microspores from buds of 3.0-3.5 mm contained mostly late uninucleate stage cells and showed some early binucleate stage cells. Microspores of buds with 3.5-4.0 mm in length were composed of mainly binucleate stage cells and decreased late uninucleate stage cells. Microspore with more than 4.0 mm were entered into binucleate stage cells of divided generative nucleus and vegetative nucleus. In 'Tamlayuchae', microspores derived from buds of 3.5-4.0 mm were observed cells of late uninucleate stage and early binucleate stage because of late microspore development. In MS-maintainer, the spring type, microspore derived from buds of 2.5-3.0 mm were observed tetrad stage cells.

• Proceedings of the Korean Society of Crop Science Conference
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• 1991.10a
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• pp.12-13
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• 1991

• Proceedings of the Korean Society of Crop Science Conference
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• 1990.10a
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• pp.16-17
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• 1990

• Proceedings of the Korean Society of Crop Science Conference
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• 1990.10a
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• pp.18-19
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• 1990

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.313-313
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• 2017

Cold stress is one of the most influenced factors to rice yield. In order to identify genes related to cold stress in fertility stage, genome-wide association study (GWAS) was conducted. Cultivated 129 rice germplasm were moved in the growth chamber under the condition of $12^{\circ}C/RH70%$(12h day/12h night when the rice plant was grown in 10 DBH(days before heading). Also, rice plant as control was moved in the green house under condition of $28^{\circ}C/RH70%$(12h day/12h night). After 4 days the plants were moved in a greenhouse. The fertility of rice plant were monitored after the grain were fully grown. The most tolerant rice germplasm to cold stress were Cheongdo-Hwayang-12 and IR38 as 63.1 and 61.8 of fertility and the most recessive rice germplasm were Danyang38 and 8 rice germplasm as 0. As a result of GWAS with re-sequencing data and fertility after cold treatment germplasm using genome association and prediction integrated tool (GAPIT), 99 single-nucleotide polymorphisms (SNPs) were observed by applying a significance threshold of -logP>4.5 determined by QQ plot. With SNPs region, 14 candidate genes responded to cold stress in fertility stage were identified.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.4
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• pp.317-323
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• 2012

For the establishment of an efficient embryogenesis from microspore culture in Brassica napus L. domestic cultivar 'Tammiyuchae', four different factors affecting microspore embryogenesis and plantlet regeneration were investigated. The highest embryogenesis rate was achieved when microspores at late uninucleate to early binucleate stage were isolated from flower buds with a length of 3.0~3.5 mm. On average, 388 embryos generated from 1 ml of microspores media. The highest number of embryos was obtained when microspores were subjected to $32.5^{\circ}C$ for 2 days. Embryogenesis of 'Tammiyuchae' was increased with increasing microspore culture density up to about $5{\times}10^4ea/mL$. Gradually higher culture density repressed embryogenesis of microspores. Regeneration rate of shoots from microspore-derived embryos was observed in MS solid medium supplemented with $0.5mg{\cdot}L^{-1}$ NAA and $1.0mg{\cdot}L^{-1}$ BA, and grew well in MS solid medium without plant growth regulators.