Human embryonic stem (ES) cells are a potential source of cells for developmental studies and for a variety of applications in transplantation therapies and drug discovery. However, human ES cells are difficult to culture and maintain at a large scale, which is one of the most serious obstacles in human ES cell research. Culture of human ES cells on MEF cells after disassociation with accutase has previously been demonstrated by other research groups. Here, we confirmed that human ES cells (H9) can maintain stem cell properties when the cells are passaged as single cells under a feeder-free culture condition. Accutase-dissociated human ES cells showed normal karyotype, stem cell marker expression, and morphology. We prepared frozen stocks during the culture period, thawed two of the human ES cell stocks, and analyzed the cells after culture with the same method. Although the cells revealed normal expression of stem cell marker genes, they had abnormal karyotypes. Therefore, we suggest that accutase-dissociated single cells can be usefully expanded in a feeder-free condition but chromosomal modification should be considered in the culture after freeze-thawing.

The objective of this study was to investigate the response of seed germination based on seed treatment of supercritical carbon dioxide (SC-CO2) sterilization. Seeds of eleven species were treated with SC-CO2 at 150 bar, 55℃ and 15 min (condition of fungi sterilization). Standard germination tests were used to evaluate germinability of seeds. Compared with non-treated seeds, SC-CO2 treatment caused significant variation of germination rate in different species. Different species showed different response to SC-CO2 treatment. The results suggest that crop of Leguminosae family is suitable for SC-CO2 sterilization.

The objective of this study was to investigate the variation of Chinese milk vetch(Astragalus sinicus L.; CMV) seed quality after flowering. We tagged individual open flowers of CMV at the day of maximum flowering(11 May) in Seoul, Korea. Seed samples were harvested serially at 15, 20, 25 and 30 days after flowering(DAF). To compare with dried seeds, non-dried seeds were tested immediately after harvest and the remaining seeds were placed at room temperature for 4 weeks. Seed length, 1000 seed weight, moisture content, germination rate(GR), mean germination time(MGT), germination speed(GS), germination performance index(GPI) and physical dormancy rate(PDR) were investigated. Seed length increased to 2.6 mm and 1000 seed weight reached up to 2.2 g until 25 DAF. Seed moisture content dramatically decreased from 20 to 25 DAF. Moisture content of non-dried seed(7.5%) was similar to that of dried seed(5.5%) at 25 DAF. The rate of seed viability reached up to 94% at 25 DAF. In case of dried seed, GR increased up to 39% at 25 DAF whereas GR of non-dried seed varied from 5 to 10%. GS and GPI of dried seed were significantly higher than those of non-dried seed since 25 DAF. PDR of dried seed has decreased since 20 DAF, whereas PDR of non-dried seed has increased. GR, GS and GPI increased as PDR decreased. Our results evidenced that PDR might be one of major factor in variation of seed quality, of which development was completed at 25 DAF.

A new bright white gladiolus “White Lace” was released by the National Horticultural Research Institute (NHRI) in 2004. A cross was made between late flowering white cultivar “White Goddess” and vigorous white cultivar “Amsterdam”. It was crossed in 1999 and finally selected in 2004 after investigation of the characteristics for 5 years from 2000 to 2004. “White Lace” has a bright white color and multi-flowering florets more than 20 florets with good simultaneous flowering more than 8 florets. This cultivar is middle flowering without stem bending. It has good production of cormlets, vigorous growth and resistant to virus, Fusarium and Thrips. The width of “White Lace” flower is 11.5 cm. The plant height is 137cm. Days to flowering of “White Lace” is average 93days in summer season.

Using fluorescent microscopy and Nomarski`s interference microscopy, pollen tube growth, and embryo andendosperm development were observed to elucidate interspecific cross-incompatibility in the genus of Fagopyrum. Interspecifichybrdization between Fagopy