• 한국약용작물학회지
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• 제23권2호
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• pp.144-149
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• 2015

The peel of Citrus sunki exhibits multiple biological activities such as anti-oxidant, anti-inflammation and anti-obesity, but little is known about neurodegeneration-related activities. In this study, we investigated the protective effect of ethanolic extract from both immature and mature Citrus sunki peel on neuronal cell death. Treatment of the neuroblastoma cell line SH-SY5Y with $MPP^+$, an inducer of Parkinson disease model, increased cell death in a dose dependent manner. Increased levels of active caspase-3 and cleaved PARP were detected. Treatment with immature Citrus sunki peel extract significantly reduced $MPP^+$-induced neurotoxicity. Cytoprotection with immature Citrus sunki peel extract was associated with a decrease in caspase-3 activation and PARP cleavage. In contrast, mature Citrus sunki peel extract had no significant effects. These data suggest that immature Citrus sunki peel extract may exert anti-apoptotic effect through the inhibition of caspase-3 signaling pathway on $MPP^+$-induced neuronal cell death.

• 한국산학기술학회논문지
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• 제21권4호
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• pp.538-545
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• 2020

한미 FTA 체결 이후 미국산 오렌지의 지속적인 수입증가에 따른 국내 감귤산업 파급영향에 대한 관심이 높다. 이 연구는 한미 FTA 발효 이후 2012-2017년 동안의 감귤산업의 변화를 계측하고, 한미 FTA 도입이 감귤산업에 미치는 사후 영향을 평가하였다. 이 연구는 분석을 위해 감귤류를 노지감귤, 하우스감귤, 만감류 부문으로 구분하고, 각 부문별 수급균형모형을 구축하여 시뮬레이션 분석에 이용하였다. 각 부문내 주요 방정식들은 응용계량경제학 방법을 이용하여 추정하고, 각 부문별 수급구조모형은 동태축차적 시뮬레이션모형으로 구축하여 2012-2017년 동안에 대해 연차별로 정책 시뮬레이션이 가능하도록 하였다. 각 모형은 작물연도를 기준으로 구축되었고, 해당 시기에 수입되는 오렌지, 체리 등에 수입산 대체가능 작물에 대한 효과를 고려할 수 있도록 설계되었다. 시뮬레이션 분석에 앞서 각 부문별 모형에 대한 예측력을 RMSPE, MAPE, Theil의 불균등계수 등을 기준으로 검토하였다. MAPE 기준으로 노지감귤, 하우스감귤, 만감류의 재배면적 1-7%, 생산량 5-9%, 소비량 5-10%, 경락가격 5-10% 내외의 오차율을 보여, 각 부문별 모형의 주요 변수에 대한 추정치들의 예측력이 전반적으로 양호한 수준으로 나타났다. 예측력 검토결과를 바탕으로 시뮬레이션 분석을 실시한 결과, 한미 FTA 발효 이후 2012-2017년 연평균 조수입(실질)이 노지감귤 23.9억 원, 하우스감귤 30.1억원, 만감류 151.1억 원 감소한 것으로 나타났다. 또한 이 논문은 기존에 2018년 정부부문(KREI)에서 실시한 영향평가방법 및 결과의 차이점을 비교 검토하고 해석시 유의사항 및 정책적 함의를 제안하고 있다.

• The Plant Pathology Journal
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• 제37권3호
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• pp.268-279
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• 2021

Citrus scab, caused by the fungal pathogen Elsinoë fawcettii, is one of the most important fungal diseases affecting Citrus spp. Citrus scab affects young tissues, including the leaves, twigs, and fruits, and produces severe fruit blemishes that reduce the market value of fresh fruits. To study the molecular responses of satsuma mandarin (C. unshiu) to E. fawcettii, plant hormone-related gene expression was analyzed in response to host-compatible (SM16-1) and host-incompatible (DAR70024) isolates. In the early phase of infection by E. fawcettii, jasmonic acid- and salicylic acid-related gene expression was induced in response to infection with the compatible isolate. However, as symptoms advanced during the late phase of the infection, the jasmonic acid- and salicylic acid-related gene expression was downregulated. The gene expression patterns were compared between compatible and incompatible interactions. As scabs were accompanied by altered tissue growth surrounding the infection site, we conducted gibberellic acid- and abscisic acid-related gene expression analysis and assessed the content of these acids during scab symptom development. Our results showed that gibberellic and abscisic acid-related gene expression and hormonal changes were reduced and induced in response to the infection, respectively. Accordingly, we propose that jasmonic and salicylic acids play a role in the early response to citrus scab, whereas gibberellic and abscisic acids participate in symptom development.

• The Plant Pathology Journal
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• 제38권4호
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• pp.287-295
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• 2022

Citrus tristeza virus (CTV) is efficiently transmitted in a semi-persistent manner by the brown citrus aphid (Toxoptera citricida (Kirkaldy)). Currently, the most sensitive method for detecting plant viruses in insect vectors is reverse-transcription quantitative polymerase chain reaction (RT-qPCR). In this study, the elongation factor-1 alpha (EF-1α) gene and acidic p0 ribosomal protein (RPAP0) gene were confirmed to be suitable reference genes for RT-qPCR normalization in viruliferous T. citricida aphids using the geNorm, NormFinder, and BestKeeper tools. Then the relative CTV titer in aphids (T. citricida) at different post-acquisition feeding times on healthy plants was quantified by RT-qPCR using EF-1α and RPAP0 as reference genes. The relative CTV titer retained in the aphids gradually decreased with increasing feeding time. During the first 0.5 h of feeding time on healthy plants, the remaining CTV titer in aphids showed about 80% rapid loss for the highly transmissible isolate CT11A and 40% loss for the poorly transmissible isolate CTLJ. The relative CTV titer in aphids during more than 12 h post-acquisition times for CT11A was significantly lower than at the other feeding times, which is similar to the trend found for CTLJ. To our knowledge, this is the first report about the relative titer variation of CTV remaining in T. citricida at different post-acquisition feeding times on healthy plants.

• The Plant Pathology Journal
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• 제39권4호
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• pp.309-318
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• 2023

Huanglongbing (HLB) is one of the most destructive diseases in citrus, which imperils the sustainability of citriculture worldwide. The presumed causal agent of HLB, 'Candidatus Liberibacter asiaticus' (CLas) is a non-culturable phloem-limited α-proteobacterium transmitted by Asian citrus psyllids (ACP, Diaphorina citri Kuwayama). A widely adopted method for HLB diagnosis is based on quantitative real-time polymerase chain reaction (qPCR). Although HLB diagnostic qPCR provides high sensitivity and good reproducibility, it is limited by time-consuming DNA preparation from plant tissue or ACP and the requirement of proper lab instruments including a thermal cycler to conduct qPCR. In an attempt to develop a quick assay that can be deployed in the field for CLas detection, we developed a real-time loop-mediated isothermal amplification (rt-LAMP) assay by targeting the CLas five copy nrdB gene. The rt-LAMP assay using various plant sample types and psyllids successfully detected the nrdB target as low as ~2.6 Log10 copies. Although the rt-LAMP assay was less sensitive than laboratory-based qPCR (detection limit ~10 copies), the data obtained with citrus leaf and bark and ACP showed that the rt-LAMP assay has >96% CLas detection rate, compared to that of laboratory-based qPCR. However, the CLas detection rate in fibrous roots was significantly decreased compared to qPCR due to low CLas titer in some root DNA sample. We also demonstrated that the rt-LAMP assay can be used with a crude leaf DNA extract which is fully deployable in the field for quick and reliable HLB screening.

• 한국약용작물학회지
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• 제22권6호
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• pp.442-448
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• 2014

The major objective of this study was to investigate the usability as cultivar for processing of new Citrus hybrid 'Hamilgam'. We investigated various antioxidant activities, such as DPPH radical, ABTS radical, Hydroxyl radical and Superoxide anion radical effect, along with total polyphenol content and total flavonoid content of Citrus hybrid 'Hamilgam', C. unshiu, C. natsudaidai. The total polyphenol content and total flavonoid content were the highest in the Hamilgam. The major flavonoids of Hamilgam and Natsudaidai were naringin and neohesperidin, and those of Unshu were narirutin and hesperidin, as determined by HPLC. Especially, the neohesperidin content of Hamilgam showed much higher (100 times over) than that of Unshu. However, the aglycone form was not found. DPPH and ABTS radical scavenging activities were the highest in Hamilgam peels. Hydroxyl radical scavenging activity was high in the order of Unshu, Hamilgam and Natsudaidai. Superoxide anion radical scavenging of 3 cultivars peels displayed low activities compared to DPPH and ABTS radical scavenging. Based on these results, Hamilgam peel extracts possess antioxidant activities and may thus serve as potential sources of functional food, cosmetic products, etc.

• 한국식품조리과학회지
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• 제21권2호
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• pp.243-249
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• 2005

제주산 감귤과즙을 이용하여 감귤식초를 제조할 목적으로 식초산 발효균 CV1과 CV2를 분리하고 식초산 생성능력을 산업적으로 이용되고 있는 균주와 비교 검정하고 165 rDNA 염기서열을 분석하고 동정하였다. 분리균은 8일간의 발효에 의하여 산도 $5.5\%$ 이상의 식초산을 생성하였으며, 감귤식초 발효에는 사과식초나 감식초 발효에 이용되고 있는 균주 보다 더욱 적합한 것으로 판정되었다. 분리한 균주는 Gluconacetobacter hanenii(CV2) 및 G. hanenii의 변이주(CV1)로 동정되었다.

• 한국응용곤충학회지
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• 제55권4호
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• pp.483-487
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• 2016

최근 감귤에서 볼록총채벌레의 피해가 증가하고 있다. 볼록총채벌레의 발생시기 및 피해증상에 관한 연구는 진행되었으나 주변 기주식물과의 관계에 관한 연구는 미흡한 실정이다. 본 연구는 볼록총채벌레 기주식물 150여 가지 중 제주도에 넓은 면적으로 재배되고 있는 망고, 키위 등의 1차 기주식물과 2차 기주식물인 감귤에서의 볼록총채벌레 발생의 유연관계를 구명하기 위해 수행되었다. 그 결과 1차 기주식물과원과 인접 감귤원의 볼록총채벌레 발생양상의 경우 밀도의 차이가 있을 뿐 발생 시기는 거의 동일하거나 감귤원에서의 발생이 약 1주일 가량 지연되어 나타났다. 1차 기주식물과원과 인접 감귤원의 트랩설치간격별 발생밀도의 경우 트랩설치간격이 짧을수록 총채벌레 포획수가 유의미하게 많았으며 과실 피해도 또한 유의미하게 높았다. 이는 1차 기주식물인 망고, 키위, 녹차 등이 인접 감귤원의 볼록총채벌레 발생에 직접적인 영향을 주고 있는 것을 나타내며 이는 추후 감귤원의 볼록총채벌레 방제연구에 기초자료로 활용 될 수 있을 것으로 생각된다.

• 한국식품저장유통학회지
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• 제2권2호
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• pp.251-257
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• 1995

In order to determine the quality of Citrus unshiu(medium cultivar of satsuma mandarin) produced in Cheju, citrus fruits sampled at sorting places and harvested directly on citrus tree in south and north area of Cheju were analyzed. The fruits were grown in size till early of November, and soluble solids were increased continuously after that. Compared with the quality of citrus fruits as a factor of soluble solids, firmness, total sugar, pH, and color index, the optimum harvest periods were supposed to be reasonable from early of December for C. unshiu Marc. var. yonezawa and C. unshiu Marc. var. hayashi, Fruit weights and peel thickness had a linear correlation with increasing fruit size, but soluble solids and acid contents had not a correlation. The selection of C. unshiu variety was needed to determine by the properties of storage.

• 식물병과 농업
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• 제5권1호
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• pp.34-40
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• 1999

The virus infection rates and disease symptoms of three major citrus viruses, citrus tristeza virus (CTV), satsuma dwarf virus (SDV), and citrus tatter leaf virus (CTLV), were investigated at 35 citrus orchards in Cheju Island from 1995. The infection rates of CTV, SDV, and CTLV were 69.8%, 8.6%, and 9.3%, respectively. However, depending on cultivars there were significant differences in the infection rates. The infection rates of CTV were highest in early satsuma mandarin (Citrusunshiu) with 80.9% and lowest in very early satsuma mandarin with 51.9%. In SDV, the highest was in very early stasuma mandarin with 23.1% and the lowest was in early satsuma mandarin with 6.3%. And the highest infection rate in very early satsuma mandarin with 17.9% and the lowest in tangors with 7.3% in CTLV. The symptoms of virus-infected citrus were very diverse; small and abnormal shape of fruits, abnormal leaves such as narrow boat and small spoon shapes of leaves, stem-pitting on the twig, bud-union crease and swelling of the graft part, reduction of the plant vigor and poor yields.