Backgrounds : Pomelo (Citrus grandis Osbeck) is the kind of citrus fruit which is Dicotyledoneae belongs to Rutaceae and special product in Jeju island. According to the previous researches, coumarin, eliocitrin, naringin are identified and these kinds of constituents revealed to be effective as anticancer, antioxidant, and antidiabetic. Until recently, there are many investigations about its functional properties were reported, but investigation about biological activities depend on extraction conditions are not sufficient. Methods and Results : 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was performed by the method of Blois with minor modification. After adding DPPH radical to each sample solutions, the mixtures were incubated in 30 minutes at aphotic place. Then, the degree of scavenging activity was recorded by microplate reader at 490 nm. The scavenging activity was expressed by RC50, which is the concentration of sample solution necessitated to scavenge 50% DPPH radical against negative control. For α-glucosidase inhibitory activity, the method using p-nitrophenyl-α-D-glucopyranoside (pNPG) was applied. To each samples, α-glucosidase and pNPG were mixed and incubated, consequently, Na2CO3 was added to terminate the reaction. Finally, absorbance was read at 450 nm. The same as DPPH radical scavenging activity, the inhibition was explicitly expressed by the amount of sample solution to inhibit 50% α-glucosidase, IC50. The 80% MeOH extract demonstrated the highest radical scavenging activity with 74.32±8.45 μg/ml. α-Glucosidase inhibitory activity was carried out to evaluate the inhibitory activity of sugar digestion and absorption and 60, 80% MeOH extract exhibited 416.35±11.07 μg/ml and 336.57±2.03 μg/ml, respectively. Conclusion : The DPPH radical scavenging and α-glucosidase inhibitory activity were evaluated in this study. The highest DPPH radical scavenging activity was seen in 80% Citrus grandis Osbeck MeOH extract, following 60% MeOH extract exhibited the second highest scavenging activity. Also, 80% MeOH extract showed 336.57±2.03 μg/ml, which was the highest α-glucosidase inhibition among all extracts.

Ionizing radiation directly and indirectly affects gene expression within the plant genome. To access the physiological response of rice to different types of ionizing radiation, rice seeds were exposed to gamma-ray and ion beam radiation. Exposure to ionizing radiation dramatically decreased the shoot length compared with non-irradiated plants. Fluorescence-activated-cell-sorting (FACs) was used to measure DNA contents. There were significant correlations of dose-dependent between irradiated plant and non-irradiated plant. The radicals induced by the ionizing radiation in the plant could be observed by electron spin resonance (ESR). It was confirmed that the number of free radicals in cell was greatly increased all irradiated plants than non-irradiated plant. A significant positive correlation was shown between ionizing radiation dose and signal intensity. In order to determine the Genetic diversity, AFLP analysis was conducted with the irradiated plant and non-irradiated plant. Based on band patterns, the cluster analysis was conducted to evaluate the genetic variation by using the UPGMA (Unweighted Pair Grouping Method of Averages). Genetic diversity of irradiated plants by low dose ion beam was the closest non-irradiated plant and irradiated by high dose gamma-ray was the furthest from non-irradiated. We describe the detailed methods of ionizing irradiation and discuss its applications in genetic research as well as plant breeding.

xBrassicoraphanus, a new synthetic intergeneric hybrid between Brassica rapa L. ssp. pekinensis and Raphanus sativus L., also locally known as ‘Baemoochae’, is an interesting subject for studying polyploidy and genome plasticity in the family Brassicaceae, but very few genomic and cytogenetic information. Here, we analysed the chromosome complements and pairing of the most fertile lines, BB1 and BB5, using dual-color fluorescence in situ hybridization (FISH) and genomic in situ hybridization (GISH) to check their chromosomal segregation stability. The somatic chromosome complement of B. rapa was confirmed to be 2n=20 (2.8~4.8μm), of R.sativus, 2n=18 (2.0~3.3μm), and of xBrassicoraphanus, 2n=38 (2.2~5.0μm). There were eight, eight, and seventeen metacentric pairs and two, one, and two submetacentric pairs in B. rapa, R. sativus, and xBrassicoraphanus, respectively. Additionally, three, two, and five pairs of 5S rDNA and five, three, and eight pairs of 45S rDNA were observed in B. rapa, R. sativus, and xBrassicoraphanus, respectively. This suggests that both B. rapa (AA) and R. sativus (RR) genomes, particularly the rDNA arrays, co-exist in xBrassicoraphanus (AARR) genome. In meiosis I, nineteen bivalents were most frequent, and GISH analysis showed ten bivalents from the A genome. This study would provide a useful information for further genomic study of xBrassicoraphanus and its improvement as a new promising breeding variety.