Fruits In Korea Research Articles

PCR 기법을 이용한 Phoma glomerate 의 특이검출

Phoma glomerata는 식물 잎이나 열매에 병을 일으키는 식물병원균으로 알려져 있다. 국내에서는 아직 피해사례가 없기 때문에 P. glomerata는 국내의 식물검역균으로 관리되고 있다. 본 연구는 국내에 들어오는 목재나 과일에 P. glomerata를 검출할 수 있는 방법 개발코자 수행되었다. Phoma 균주들의 translation elongation factor 1 alpha 유전자 염기서열에 기초하여 P. glomerata 특이적 PCR 프라이머를 디자인 하였고 그 특이성을 검정하였다. PCR 수행 결과 P. glomerata에서만 170 bp 크기의 밴드가 증폭되었고, 다른 비교 균주에서는 밴드가 증폭되지 않았다. 검출 감도를 평가하기 위해 기존 PCR방법과 real time PCR 방법을 이용하여 실험한 결과 최소 10 pg과 1 pg까지 각각 검출할 수 있었다. 본 연구결과는 디자인된 PCR 프라이머가 P. glomerata를 특이적으로 검출하는데 유용할 것임을 보여준다. Phoma glomerata (Corda) Wollenw. & Hochapfel is a pathogenic fungus causing spot diseases of plant leaves and fruits. This fungus is important in plant quarantine of seedlings and fruits in Korea. The aim of this study was to develop a sensitive and effective diagnostic method for P. glomerata detection in imported plants. The fungal species-specific PCR primers were designed based on the nucleotide sequences of the translation elongation factor 1 alpha gene and their specificity and sensitivity were tested. The designed primers named as PhoGlo-F and PhoGlo-R amplified specifically a 170 bp sized DNA band of the target gene from the genomic DNA of P. glomerata. No amplicon was produced from genomic DNAs of 16 other Phoma spp. and reference fungal species tested. Moreover, PhoGlo-F/PhoGlo-R primers successfully worked with real-time PCR technique. The detection limit of DNA content by conventional and real-time PCR were 10 pg and 1pg of the genomic DNA of P. glomerata, respectively. We believed that the developed makers would be very useful for P. glomerata detection.

Soft Rot of Rhizopus oryzae as a Postharvest Pathogen of Banana Fruit in Korea

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was 30°C. Sporangia were globose and 30~200 μm. Sporangiophores were usually straight, 8~20 μm, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and 90~110 μm. Sporangiospores were sub-globose or oval and 4~10 μm. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea.

Development of a new shape of pheromone trap for the bean bug, Riptortus pedestris (Hemiptera: Alydidae)

Riptortus pedestris F. [=R. clavatus (Thunberg)] is one of the most serious pests affecting the cultivation of sweet persimmon, which is one of the most important export fruits in Korea. A pheromone-baited trap has been used in attempts to control this pest. In this study, the development of a more efficient pheromone-baited trap for R. pedestris was pursued by investigating three different shapes of traps: the fish trap, the pyramidal trap, and the symmetry trap. The fish trap, which is the only one commercially available, captured the lowest number of R. pedestris, and the pyramidal trap showed moderate capture efficacy. The symmetry trap captured significantly greater numbers of R. pedestris adults (ca. 6 and 28 times more than the pyramidal and fish trap, respectively). Significantly increased trapping efficacy of the symmetry trap would be useful for mass trapping of R. pedestris.

Sugar composition and glycemic indices of frequently consumed fruits in Korea

Fruits are generally recommended for a balanced meal, as they are good sources of vitamins, minerals, and fiber, which may improve blood glucose control. However, fruits have simple sugars with a wide glycemic index (GI) range. The purpose of this study was to analyze the sugar content and composition and to determine the glycemic indices of the most frequently consumed fruits in Korea, including apple, tangerine, pear, water melon, persimmon, grape, oriental melon, and peach. The sugar content and composition of the fruits were analyzed by high performance anion-exchange chromatography (Dinonex model DX-600). The GI of the fruits was measured in 13 healthy subjects (seven females and six males) after permission was received from the University Hospital institutional review board (KHU-IRB 1114-06). The subjects consumed 50 g of glucose as a reference and carbohydrate portions of eight fruits. Blood samples were collected at 0, 30, 60, 90, and 120 min after consuming the fruits. The GI values for the fruits were calculated by expressing the increase in the area under the blood glucose response curve for each subject. As a result, the total sugar contents of 100 g fruits were: grape (13.9 g), apple (12.3 g), persimmon (11.9 g), oriental melon (11.2 g), watermelon (9.3 g), tangerine (8.9 g), peach (8.6 g), and pear (8.3 g). The GI values of the fruits were as follows: GI value of peach (56.5 ± 14.17), watermelon (53.5 ± 18.07), oriental melon (51.2 ± 18.14), tangerine (50.4 ± 15.16), grape (48.1 ± 14.05), persimmon (42.9 ± 18.92), pear (35.7 ± 14.38), and apple (33.5 ± 11.92). These findings will help individuals choose fruit for controlling blood sugar. (Korean J Nutr 2012; 45(2): 192 ~ 200)

First Report of Flyspeck Caused by Zygophiala wisconsinensis on Sweet Persimmon Fruit in Korea.

Sweet persimmon (Diospyros kaki L.), a fruit tree in the Ebenaceae, is cultivated widely in Korea and Japan, the leading producers worldwide (2). Sweet persimmon fruit with flyspeck symptoms were collected from orchards in the Jinju area of Korea in November 2010. The fruit had fungal clusters of black, round to ovoid, sclerotium-like fungal bodies with no visible evidence of a mycelial mat. Orchard inspections revealed that disease incidence ranged from 10 to 20% in the surveyed area (approximately 10 ha) in 2010. Flyspeck symptoms were observed on immature and mature fruit. Sweet persimmon fruit peels with flyspeck symptoms were removed, dried, and individual speck lesions transferred to potato dextrose agar (PDA) and cultured at 22°C in the dark. Fungal isolates were obtained from flyspeck colonies on 10 sweet persimmon fruit harvested from each of three orchards. Fungal isolates that grew from the lesions were identified based on a previous description (1). To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA sequence of a representative isolate was amplified and sequenced using primers ITS1 and ITS4 (4). The resulting 552-bp sequence was deposited in GenBank (Accession No. HQ698923). Comparison with ITS rDNA sequences showed 100% similarity with a sequence of Zygophiala wisconsinensis Batzer & Crous (GenBank Accession No. AY598855), which infects apple. To fulfill Koch's postulates, mature, intact sweet persimmon fruit were surface sterilized with 70% ethanol and dried. Three fungal isolates from this study were grown on PDA for 1 month. A colonized agar disc (5 mm in diameter) of each isolate was cut from the advancing margin of a colony with a sterilized cork borer, transferred to a 1.5-ml Eppendorf tube, and ground into a suspension of mycelial fragments and conidia in a blender with 1 ml of sterile, distilled water. The inoculum of each isolate was applied by swabbing a sweet persimmon fruit with the suspension. Three sweet persimmon fruit were inoculated per isolate. Three fruit were inoculated similarly with sterile, distilled water as the control treatment. After 1 month of incubation in a moist chamber at 22°C, the same fungal fruiting symptoms were reproduced as observed in the orchards, and the fungus was reisolated from these symptoms, but not from the control fruit, which were asymptomatic. On the basis of morphological characteristics of the fungal colonies, ITS sequence, and pathogenicity to persimmon fruit, the fungus was identified as Z. wisconsinensis (1). Flyspeck is readily isolated from sweet persimmon fruit in Korea and other sweet persimmon growing regions (3). The exposure of fruit to unusual weather conditions in Korea in recent years, including drought, and low-temperature and low-light situations in late spring, which are favorable for flyspeck, might be associated with an increase in occurrence of flyspeck on sweet persimmon fruit in Korea. To our knowledge, this is the first report of Z. wisconsinensis causing flyspeck on sweet persimmon in Korea.

유통 중인 과일류의 중금속 모니터링

국내에는 과일류 중 중금속의 기준규격은 없으나, Codex에서는 과일류 중 납 함량 규격을 0.1 mg/kg으로 설정하여 관리하고 있다. 이에 따라 우리나라에서 유통 중인 과일류의 중금속 함량 규격을 설정하고자 일일 섭취량이 많은 과일 8종(오렌지, 사과, 바나나, 배, 감귤, 감, 망고, 키위), 927건을 수거하여 납, 카드뮴, 비소 및 수은 함량을 수은분석기 및 ICP-MS를 이용하여 분석하였다. 표준용액첨가법에 의한 회수율은 납 86.0-110.4%, 카드뮴 81.0-104.0%, 비소 82.0-104.7%를 얻었으며, 수은분석기를 이용한 수은의 회수율은 106.5%이었다. 조사결과 국내유통 중인 과일류의 중금속 평균함량은 납 8.3, 카드뮴 0.7 비소 1.4, 수은 <TEX>$0.3{\mu}g/kg$</TEX>으로 조사되었다. 중금속의 주간섭취량을 FAO/WHO에서 안전성 평가를 위해 설정한 PTWI와 비교한 결과, 납, 카드뮴, 수은이 각각 0.17, 0.013 및 0.006%로 그 수준이 매우 낮아 우리나라에서 유통되는 이들 과일로부터 섭취하는 중금은 매우 미미하여 안전한 수준으로 판단된다. According to the Codex committee, the maximum allowable level for lead in fruits is 0.1 mg/kg. This survey was conducted as a surveillance program following the establishment of safety guideline for fruits in Korea. Concentrations of lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) were measured in 927 samples using a ICP-MS and a mercury analyzer. The recoveries of microwave digestion method were 86.0-110.4% for Pb, 81.0-104.0% for Cd and 82.0-104.7% for As by standard addition method. The recovery of direct mercury analyzer was 106.5% for Hg. The average levels of Pb in <TEX>${\mu}g/kg$</TEX> were <TEX>$10.0{\pm}12.8$</TEX> for apple, <TEX>$8.8{\pm}10.9$</TEX> for pear, <TEX>$4.1{\pm}4.4$</TEX> for persimmons, <TEX>$14.9{\pm}12.3$</TEX> for mandarin, <TEX>$7.1{\pm}6.5$</TEX> for orange, <TEX>$3.1{\pm}3.3$</TEX> for banana, <TEX>$8.8{\pm}8.9$</TEX> for kiwi, and <TEX>$9.3{\pm}9.7$</TEX> for mango. The average levels of Cd in <TEX>${\mu}g/kg$</TEX> were <TEX>$0.4{\pm}0.3$</TEX> for apple, <TEX>$2.0{\pm}1.6$</TEX> for pear, <TEX>$0.3{\pm}0.3$</TEX> for persimmon, <TEX>$0.1{\pm}0.1$</TEX> for mandarin, <TEX>$0.1{\pm}0.1$</TEX> for orange, <TEX>$1.3{\pm}1.8$</TEX> for banana, <TEX>$0.5{\pm}0.5$</TEX> for kiwi, and <TEX>$0.7{\pm}0.6$</TEX> for mango. The average levels of As in <TEX>${\mu}g/kg$</TEX> were <TEX>$2.0{\pm}2.1$</TEX> for apple, <TEX>$1.2{\pm}1.3$</TEX> for pear, <TEX>$1.5{\pm}1.2$</TEX> for persimmon, <TEX>$0.8{\pm}0.3$</TEX> for mandarin, <TEX>$1.5{\pm}0.5$</TEX> for orange, <TEX>$1.8{\pm}1.2$</TEX> for banana, <TEX>$1.6{\pm}1.5$</TEX> for kiwi, and <TEX>$1.2{\pm}1.5$</TEX> for mango. The average levels of Hg in <TEX>${\mu}g/kg$</TEX> were <TEX>$0.5{\pm}0.4$</TEX> for apple, <TEX>$0.3{\pm}0.2$</TEX> for pear, <TEX>$0.2{\pm}0.1$</TEX> for persimmon, <TEX>$0.2{\pm}0.1$</TEX> for mandarin, <TEX>$0.2{\pm}0.1$</TEX> for orange, <TEX>$0.2{\pm}0.0$</TEX> for banana, <TEX>$0.2{\pm}0.2$</TEX> for kiwi, and <TEX>$0.6{\pm}0.2$</TEX> for mango. Based on the Korean public nutrition report 2005, these levels (or amounts) are calculated only at 0.17% for Pb, 0.013% for Cd and 0.006% for Hg of those presented in provisional tolerable weekly Intake (PTWI) which has been established by FAO/WHO. Therefore, the levels presented here are presumed to be adequately safe.

숯 가공 포장재가 배의 품질변화에 미치는 영향

The packaging of fruits is very important because appropriate packaging can optimize the maintenance of freshness of fruits during their distribution in low or normal temperatures until the products reach consumers. The focus of this study was on the use of functional packaging materials for the post-harvest maintenance of the freshness of fruits. Oak charcoal has excellent far infrared emission and ethylene absorption qualities, and we developed a charcoal-processing packaging linerboard to evaluate the possibility for the use of charcoal as a functional packaging material for pears. Oriental pears of the Niitaka cultivar used in this study account for about 70% of pears harvested every year, and are a very popular domestic fruit in Korea. Pears packaged in packaging materials processed with charcoal were of significantly higher quality (p<0.05) than those packaged with conventional packaging materials, suggesting that charcoal-processed packaging materials can be used as functional packaging material for extending the storability and distribution time of fruits. Charcoal-coated linerboard was shown to be the most appropriate packaging material based on its compression strength, ethylene absorption performance, and the firmness and minimal weight loss of pears.

Generation of an Arginine Auxotrophic Mutant of Colletotrichum acutatum as a Recipient Host for Insertional Mutagenesis

Colletotrichum acutatum was the main cause of the recent outbreaks of anthracnose on pepper fruit in Korea. To facilitate molecular analysis of C. acutatum, we generated an arginine auxotrophic mutant of the C acutatum strain JC24 using a targeted gene replacement strategy. A 3.3-kb genomic region carrying an ortholog (designated CaARG2) of the fungal gene encoding N-acetylglutamate synthase, the first enzyme of arginine biosynthesis in fungi, was deleted from the fungal genome. The mutant exhibited normal growth only when arginine was exogenously supplied into the culture medium. Transformation of the arginine auxotrophic mutant with a plasmid DNA carrying an intact copy of CaARG2, which was smaller than the deleted region in the mutant, not only caused random vector insertions in the fungal genome, but also recovered both hyphal growth and pathogenicity of the mutant to the wild-type level. Using this new selection system, we have successfully developed a restriction enzyme-mediated integration procedure, which would provide an economically efficient random mutagenesis method in C. acutatum.

Bacillus amyloliquefaciens IUB158-03이 생산하는 항진균물질의 분리와 항균활성

For the control of pathogenic microorganisms, Bacillus spp. were isolated from diseased pepper fruits in Korea. Among them, Bacillus sp. IUB158-03 showed high inhibitory effect on mycelial growth and spore germination of C. gloeosporioides and Botrytis cinerea. The strain was identified as B. amyloliquefaciens IUB158-03 based on its physiological, biochemical characteristics and Microlog analysis. The highest level of antifungal substances by B. amyloliquefaciens IUB158-03 were obtained when the bacterium was cultured in medium containing 2% soluble starch, 3% yeast extract, 0.5% tryptone, 0.5% , and 1% NaCl (pH 6.0) at for 72 hrs. The antifungal substances were purified by butanol extraction, silica gel column chromatography, preparative thin layer chromatography, and high performance liquid chromatography. The purified antifungal substance was confirmed 0.27 by TLC. This substance exhibited antifungal activity against Fusarium solani, Rhizoctonia solani, Botrytis cineria, Alternata alternaria of plant pathogenic fungi and Trichophyton mentagrophytes, Epidermophyton floccosum, Cryptococcus neoformans of human pathogenic fungi.

Analyses of the Less Benzimidazole-sensitivity of the Isolates of Colletotrichum spp. Causing the Anthracnose in Pepper and Strawberry

The anthracnose disease on pepper fruits in Korea was caused by Colletotrichum acutatum as well as C. gloeosporioides. Since C. acutatum showed less sensitivity to benomyl, it was analyzed whether the less sensitivity was given by the same mechanism for the fungicide resistance of C. gloeosporioides. The isolates of C. acutatum were less sensitive to the three benzimidazole fungicides tested, benomyl, carbendazim, and thiophanate-methyl. However, the of C. acutatum isolates were different from the resistant isolates of C. gloeosporioides in their response to diethofencarb, one of N-phenyl-carbamates; the former was still less sensitive to diethofencarb than the latter. The differences in the resistance mechanisms in two species were conspicuous in sequence analysis of the tub2 genes. The genes from C. acutatum did not show any non-synonymous base substitutions at the regions known to be correlated with the benzimidazole-resistance. All of these data may indicate that the less sensitivity of C. acutatum to benomyl is based on different mechanism(s) from that of C. gloeosporioides.

Identification and Distribution of Two Fungal Species Causing Sclerotial Disease on Mulberry Fruits in Korea

A total of 520 overwintered sclerotia were collected from surface of soil under mulberry trees in six locations in Korea during February in 2006 and 2007. The collected sclerotia were tested for their germination in vitro and identified based on their morphological characteristics. Out of all sclerotia tested, 523% of the sclerotia germinated and produced two types of apothecia. The two types of fungi occurred from the sclerotia at the ratio of 49.8 vs. 50.2. The fungal type with cup-shaped apothecia was identified as Ciboria shiraiana and another type of fungus with club-shaped apotheeia as Scleromitrula shiraiana. Taxonomy and distribution of the two sclerotial fungi were described and discussed.