Earticle

The study was conducted to analyze the genetic characteristic of young shoot homogenates for coagulation and browning in citrus. Genotypes of some cultivars and Korean landraces used for conventional cross breeding programs were proposed from evaluating segregant ratio of segregant seedlings for coagulation and browning. An evaluation of coagulation was conducted by homogenizing young shoots with phosphate buffer and transferring it immediately on blotting paper and that of browning by homogenizing, centrifuging, and standing it for 1-2 days at room temperature. Mandarins including ‘Wilking’, ‘Fina’, ‘Murcott’, and ‘Dancy’ and a Korean landrace of ‘Sadookam’ were classified into coagulation and a pumelo of ‘Tanigawa’ and Korean landraces of ‘Dangyooza’ and ‘Byungkyool’ into non-coagulation type. Browning type included mandarins or mandarin hybrids of ‘Benibae’, ‘Wilking’, ‘Fina’, ‘Kiyomi’, ‘Dancy’, and ‘OkitsuWase’ satsuma and non-browning included a pumelo of ‘Tanigawa’, a mandarin of ‘Murcott’, and some Korean landraces of ‘Sadookam’, ‘Byungkyool’, and ‘Dangyooza’. The prediction of genotypes for coagulation and browning was possible by evaluating the segregation ratio of some their hybridized seedlings.

Citrus is one of the most wide cultivated fruits in the world. Pollen morphology of citrus is one of the most important characteristics used in classification and reproductive biology studies. In this paper we reviewed the progress of palynological characters including pollen size, aperture, and exine ornamentation. Pollen grains of Citrus are usually circular in shape with 4-colporate aperture, and elliptical equatorial view. The exine thickness ranges from 1-3 μm. The size of grains is small to medium with polar axis ranging from 22-45 μm. This basic knowledge on citrus pollen morphology provides a fundamental information for understanding the development and fertility of citrus pollen.

본 연구에서는 제주산 및 태국산, 페루산 망고 의 품질을 비교평가하기 위해 과실의 TSS 측정 과 DPPH활성산소 소거활성 검정을 실시해보았 다. 실험에 사용된 망고들 중 페루산 망고는 TSS가 가장 높았고, 태국산 망고는 DPPH활성산 소 소거능력에서 가장 높은 활성을 보였다. 제주 산 망고는 다른 망고들에 비해 TSS와 항산화 활 성이 가장 낮았다. 이들 결과는 아마도 자외선 양이 수입산 망고의 품질에 영향을 미치며, 미숙 과에서의 항산화 활성이 완숙과에서의 항산화 활 성보다 높다는 점이 시사되었다.

In this study, we compare the quality of the mango cultivated in Jeju and imported mango from Peru, Thailand by evaluating the total soluble solids (TSS) and antioxidant activity (AA) from ethanol extracts of the fruit. Among the mangoes used in the experiment, the Peruvian mango was the highest in TSS and Thai mango was the highest in AA. Jeju mango was lowest in TSS and AA for the other mangoes. These results suggest that the ultraviolet (UV-C) dose improves the quality of the mango. Also, suggest that the AA in immature mango was higher than the AA in full ripe mango.

Recent sequencing technology development has allowed us to investigate millions to billions of genetic information in environments. Illumina sequencers are one of the most frequently used next generation sequencing (NGS) platforms to study microbiome. While this technology has been extensively applied in medical field, known as a gut microbiota study, fewer studies have done for agricultural area. One gram of soil may contain more than 100 billions of microorganisms with more than a thousands of different species. Recent studies have reported important roles of soil microbiota in growing crops through providing extra nutrients as well as conferring resistance against toxic substances. Although soil microbiome study has been increased dramatically, it deserves more attentions, especially in the field of agriculture. This review provides a guidance toward non-microbiologist nor bioinformaticians to acknowledge the importance of NGS-based microbial ecology study, a microbiome research.

In this research, the taxonomy of Pteridophyta spontaneously growing in Jejudo Dongbaek Dongsan Park by the morphological observation was compared to that by the analysis of DNA sequences. Among 25 species of the Pteridophyta 21 species were collected in Dongbaek Dongsan Park and the others were in Jejudo outside of the Park. Sufficient amount of total DNA were extracted in 18 species but 7 species were not. Using the universal primer c and d, DNA of 18 species were successfully amplified and whereas DNA of 3 species were used other universal primer, respectively. Except Cyrtomium fortunei, which was shown 99%, 20 species of Pteridophyta amplified DNA represented 100% identity with the taxonomy by the morphological observation.

We examined the traits of Gungcheon cultivar as control and first selected 11 mutant lines. Mutant lines showed commonly higher fruit hardness than control cultivar. Sugar content was higher in B, E and I lines out of mutant lines. The red color of E line, F line and H line was high in the analysis of the fruit peel color. On the other hand, the degree of redness was low in C line, D Line, J Line and K line. Of these, the two lines showed a green color, indicating a delay in the transition from green to orange in November. These results suggest that the trait derived by the mutation can be used for the breed development.

Colchicine is a useful chemical used to induce polyploidy in plants. Diploids of C. unshiu 'Sangdojoseang' and C. hybrid 'Sagakashi No. 34' were treated with colchicine to develop tetraploids for breeding of seedless citrus varieties and their several characters were investigated. Buds on scions were treated with 0.1% colchicine solution twice for 15 minutes each time and grafted onto trifoliate orange rootstocks. As the result of polyploidy analysis of new leaves by flow cytometry, we got 1 tetraploid of 'Sangdojoseang' and 4 tetraploids of 'Sagakashi No. 34'. Tetraploids showed unvigorous growth compared with diploids. Leaves of tetraploids were thicker and blunter compared with diploids. Stoma density was lower and stoma size was larger than that of diploids. Tetraploids showed shorter length and larger width in flower bud, petal, pistil and ovary than those of diploids.

Yuja(Citrus junos) is good at cold and skin care, and has prevention effect on fatigue and aging. It is used as extract, tea, vinegar and etc. But its fruits are very seedy. Tetraploid seedlings were firstly induced by colchicine treatment to development of seedless new variety for processing industry. And leaf thickness was compared between diploid and tetraploid seedlings to development new more efficient ploidy testing method. Yuja seeds were immersed at 0.2% colchicine solution up to 48 hours and in 0～0.4% colchicine solution for 24 hours, but there were no difference among treatments. So, it is considered colchicine is not effective in tetraploid induction of yuja seeds. Leaf thickness was measured using a micrometer in order to find a new efficient method for discrimination of tetraploid among a lot of seedlings. The diploid and tetraploid leaf thicknesses were different at 0.19 ± 0.02 mm and 0.23 ± 0.03 mm, respectively. Seedlings its leaf thickness was more thicker than 0.23 mm, was all tetraploid. In addition, the tetraploid roots were characterized by small number, short and thick. The roots of diploids have occasionally the same shape, but leaf thickness is thinner than tetraploid. Therefore, it is possible to be sure that the seedlings with thick leaves, small number of roots, short and thick roots are tetraploid.

Guava is native to the tropics of the Americas and is widely distributed throughout the subtropical region. It is known to be effective in diabetes. Guava is one of the subtropical crops currently grown in Jeju and other regions. In order to search another physiological activities, we investigated the antioxidant activity of extracts after hot water extracts of Guava (Psidium guajava L.) at four stages of development. As a result, antioxidative activity was found in all leaf extracts. The highest antioxidant activity was observed in the youngest leaves at the drying, and in the Old Red and Mature Green leaves at the freezing storage.