• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.2
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• pp.69-77
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• 2007

We examined the depigmentation effect on Korean traditional citrus 17 species. With B16 melanoma cells, we have seen inhibition of the tyrosinase and melanin formation, which eventually were dose dependently decreased by three citrus fruits, immature Citrus unshiu, Citrus hassaku, and Citrus sinensis ${\times}$ reticulata as compared with positive control. Also, we examined expression of tyrosinase, DOPAchrome tautomerase (TRP-2), and DHICA oxidase (TRP-1) which affect melanin synthesis. Especially, immature Citrus unshiu decreased the protein levels of tyrosinase and TRP-1. In conclusion, immature Citrus unshue showed the strongest activity in all the experiments mentioned above and we expect that it can be used for preventing UV-induced pigmentation.

• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.669-676
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• 2004

Functional characteristics of citrus products fermented with lactic acid bacterium and yeast were investigated. Flavonoid composition of fermented citrus extracts increased significantly compared to control, leading to increases of naringenin and hesperetin concentrations. All citrus extracts showed anti-apoptotic effects in HepG2 cells regardless of fermentation, with citrus-fermented products showing greater anti-apoptotic effect and intracellular Reactive Oxygen Species content reduction compared to native citrus extracts. Male Sprague-Dawley rats were orally dosed with native or fermented citrus extracts. Singnificantly higher body weight reductions were observed in higher fermented citrus-dosed (100 mg/kg body weight) group compared to the other groups. Plasma total cholesterol level was slightly, but not significantly, reduced. Fatty liver formation induced by high-fat diet was significantly suppressed in rats administered with fermented citrus extracts. Results suggest fermented citrus extracts have potent anti-apoptotic and anti-oxidative activities in vitro, and inhibitory activity against fatty liver formation by high-fat diet in vivo.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.535-539
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• 2009

This study was conducted to identify plant-parasitic nematodes and determine the distribution pattern of the nematode species in citrus fruit orchards in Korea from April to August, 2008. Plant-parasitic nematodes were found in 139 among 178 soil samples. Tylenchulus semipenetrans was collected from 85 out of 94 Citrus unshiu orchards examined (90.4%). C. junos orchards infested with T. semipenetrans were 60 out of 84 (71.4%). However, proportion of dominant species between the two was different. At domestic Citrus orchards, it proved that T. semipenetrans was the most important plant-parasitic nematode from this study. The overall frequency of the plant-parasitic nematodes was positively correlated with the cultivation years. More alkaline soils tended to harbor more T. semipenetrans. However the correlation coefficient between the two was very low.

• Korean journal of applied entomology
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• v.50 no.3
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• pp.203-208
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• 2011

This study was conducted to evaluate Geometridae (Lepidoptera) species as pests and the damage they cause in citrus orchards in Jeju, Korea. Seven geometridae species occurred in citrus orchards: Ascotis selenaria, Ectropis excellens, Menophra senilis, Biston panterinaria, Ourapteryx nivea, Odontopera arida and Hypomecis punctinalis. Among them, A. selenaria was most abundant, followed by E. excellens and M. senilis. Most Geometridae larvae fed on citrus leaves, but A. selenaria larvae ate fruits and leaves. Fruit damage of Citrus unshiu appeared as gnawed scars caused by young larvae feeding on fruit surface. Fruit damage on Shiranui fruits appeared as a wide hole or deep scars caused by feeding by mature larvae (6th instar). Citrus leaves damage due to Geometridae larvae was high during May to June. Fruit damage started in late June as the spring-shoots of citrus hardened and increased sharply in late July. In the field experiment, fruit damage in the late season reached 4.2% in both 2008 and 2009 and reached 5.2% in 2010. In citrus orchards, A. selenaria larvae started to appear in mid-May and their populations peaked in mid June, late July, and early to mid-September. Adult males of A. selenaria had a maximum peak in mid-May, and two other peaks in early to late July and late August to early September. A. selenaria male adults were collected in a pheromone traps constantly throughout Jeju Island.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.462-469
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• 2009

This study was conducted to investigate total polyphenolic contents and reactive oxygen species (ROS) scavenging effects of extracts from peels of ten Jeju native citrus fruits according to the harvest from August 2006 to February 2007. Total polyphenolic contents from methanol extracts of citrus peel were the highest in Jigak (Citrus aurantium) and Hongkyool (C. tachibana) by over 200 mg% in the unmatured period, from the late August to the late September, and all the citrus peels mostly decreased while ripening. Scavenging effect of superoxide anion radical showed good correlation with total polyphenolic contents. The unmatured periods of Hongkyool and Jigak were the highest with more than 60%. Hydrogen peroxide scavenging activity was the highest in Sadoogam (C. pseudogulgul) at 73.8% in late August and the second highest activity was observed in Jigak at near 70%, and all the citrus peels decreased during ripening. Hydroxy radical scavenging activity were the highest among all the ROS scavenging activities, especially in the Jigak and Dangyooja (C. grandis) at 75.1% and 74.6%, respectively, and not much affected by increased maturity of the fruits. Nitric oxide radical scavenging activity was the highest in Bungkyool (C. platymama) at 58.4% in late February, and increased with fruit ripening. In this study, Jigak was generally the highest in the polyphenolic contents and ROS scavenging activities, so the further studies are needed for industrial applications.

• The Plant Pathology Journal
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• v.15 no.6
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• pp.335-339
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• 1999

Citrus tristeza virus(CTV), an aphid-borne closterovirus, is one of the most destructive pathogens of citrus. It has caused rapid decline in growth, stem pitting and death in citrus trees. A reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed for detection of CTV and investigation of the CTV infection status of citrus and its related cultivars in Cheju island. For RT-PCR based CTV detection, primers were designed to amplify 670bp of coat protein gene. A screening test for CTV in citrus cultivars was conducted from March to July in 1999. Seventy individual citrus trees representing 9 species of 3 genera were tested. The infection rates of CTV for leaves from the years or older trees of late maturing citrus varieties such as Yuzu (C. junos Sieb. ex Tanaka), Navel orange (C.sinensis Osbeck), Kiyomitanger (C. unshiu x C. sinensis), and Shiranuhi ((C. unshiu x C. sinensis) x C. reticulata) were 100%, 80%, 60%, and 60% respectively. The CTV infection rates in Early satsuma mandarins such as 'Miyagawa Early' Satsuma mandarins (C. unshiu Marc. var. Miyagawa) and 'Okitsu Early' Satsuma mandarins (C. unshiu Marc. var. Okitsu) were 100%, and 60%, respectively. CTV was not detected in Cheju native Dangyooja (C. unshiu Marc. var. Osbeck), Trifoliate orange (Poncirus trifoliata) and Kumquat (Fortunella margarita Swingle). In conclusion, RT-PCR assay can be successfully applied to the detection of CTV in citrus trees.

• Journal of Plant Biotechnology
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• v.49 no.4
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• pp.271-291
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• 2022

Pectin methylesterase (PME) plays an important role in vegetative and reproductive development and biotic/abiotic stress responses by regulating the degree of methyl-esterification of pectic polysaccharides in the plant cell wall. PMEs are encoded by a large multigene family in higher land plant genomes. In general, the expression of plant PME genes shows tissue- or cell-specific patterns and is induced by endogenous and exogenous stimuli. In this study, we identified PME multigene family members (CsPMEs) from the sweet orange genome and report detailed molecular characterization and expression profiling in different citrus tissues and two fruit developmental stages. We also discussed the possible functional roles of some CsPME genes by comparing them with the known functions of PMEs from other plant species. We identified 48 CsPME genes from the citrus genome. A phylogenetic tree analysis revealed that the identified CsPMEs were divided into two groups/types. Some CsPMEs showed very close phylogenetic relationships with the PMEs whose functions were formerly addressed in Arabidopsis, tomato, and maize. Expression profiling showed that some CsPME genes are highly or specifically expressed in the leaf, root, flower, or fruit. Based on the phylogenetic relationships and gene expression profiling results, we suggest that some CsPMEs could play functional roles in pollen development, pollen tube growth, cross incompatibility, root development, embryo/seed development, stomata movement, and biotic/abiotic stress responses. Our results shed light on the biological roles of individual CsPME isoforms and contribute to the search for genetic variations in citrus genetic resources.

• The Plant Pathology Journal
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• v.33 no.1
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• pp.87-94
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• 2017

Citrus canker disease decreases the fruit quality and yield significantly, furthermore, emerging of streptomycin-resistant pathogens threatens the citrus industry seriously because of a lack of proper control agents. Small synthetic antimicrobial peptides (AMPs) could be a promising alternative. Fourteen hexapeptides were selected by using positional scanning of synthetic peptide combinatorial libraries. Each hexapeptide showed different antimicrobial spectrum against Bacillus, Pseudomonas, Xanthomonas, and Candida species. Intriguingly, BHC10 showed bactericidal activity exclusively on Xanthomonas citri subsp. citri (Xcc), while BHC7 was none-active exclusively against two Pseudomonas spp. at concentration of $100{\mu}g/ml$ suggesting potential selectivity constrained in hexapeptide frame. Three hexapeptides, BHC02, 06 and 11, showed bactericidal activities against various Xcc strains at concentration of $10{\mu}g/ml$. When they were co-infiltrated with pathogens into citrus leaves the disease progress was suppressed significantly. Further study would be needed to confirm the actual disease control capacity of the selected hexapeptides.

• Korean journal of applied entomology
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• v.39 no.1
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• pp.13-19
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• 2000

This studies was carried out to investigate the natural enemies of citrus red mite, pononychus citri and seasonal occurrence of its major beneficial insects in Yuzu groves (Chonnam province) from 1996 to 1998. Natural enemies against citrus red mite were 9 species including Oligota kashmirica benifica, 0. yasumatsui, Stethorus punctillum, Chrysopa pallens, Propylea japonica, Orius sauteri, Scolothrips takahashii, Amblyseius womersleyi and one unidentified species of thrips (Family: Phlaeothripidae). Among them, Oligota kashmirica benzficu and Stethorus punctillum were found to be dominant species. 0 . kushmirica henifica had 4-5 generations from middle May to middle November with peak in early September. S. punctillum had 3 generations from late May to late October with peak of late June to middle July. Population dynamics between predator ( 0 . kushmiricu benifica and S. punctillum) and prey (Panonychus citri) were quite well synchronized until September but predator density was decreased abruptly after October.

• Korean Journal of Pharmacognosy
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• v.10 no.1
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• pp.13-16
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• 1979

The essential oil composition by means of gas liquid chromatography, and the occurrence and distribution of flavonoid glycosides in leaves, peels and barks of citrus plants native to Je Ju island were investigated. Results indicate that the occurrence of p-cymene, d,l-limonene, linalool, geraniol and linalyl acetate in the essential oils, and of hesperidin in leaves, peels and barks are fairly common to these species.