• Korean Journal of Plant Resources
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• v.27 no.1
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• pp.51-59
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• 2014

In this study, we developed a high frequency watermelon regeneration system using three breeding lines ('B02', 'B05' and 'D04') of watermelon (Citrullus lanatus (thunb.) Matsum. & Nakai) which are differed in their fruits in shape, color of pericarp and flesh. The highest frequency of explants with callus was observed by using explants that consist of cotyledon proximal part end in all breeding lines, and the highest rate of callus induction was obtained on MS medium containing 1.0 mg/L BAP + 0.5 mg/L IAA for 'B02' (94%), 3.0 mg/L BAP for 'B05' (95%), 3.0 mg/L BAP + 0.1 mg/L IAA for 'D04' (90%). The highest shoot regeneration rates from derived callus were obtained on MS medium containing 1.0 mg/L BAP + 0.5 mg/L IAA for 'B05' (94%), and then a 'B02' (81%) with a same culture conditions, and the lowest regeneration was obtained on MS medium containing 1.0 mg/L BAP for 'D04' (56%). Regenerated plants showed the best rates of root formation on MS containing 0.1 mg/L IBA for 'B02' (67%), 0.1 mg/L NAA for 'B05' (87%), 0.5 mg/L IAA for 'D04' (88%). The regenerated plants showed a 100% survival rate in soil condition. The tissue culture and regeneration conditions obtained from this study will be useful for regenerating plants in breeding applications, and will be a useful tool for further genetic transformation studies on watermelons.

• Journal of Life Science
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• v.18 no.7
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• pp.1019-1022
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• 2008

The chromosome numbers and compositions were investigated in four cultivated species of Cucurbitaceae; Cucumis sativus L., Citrullus lanatus (Thunb.) Matsum. et Nakai, Cucumis melo L., Luffa cylindrica (L.) Roemer. through general aceto-orcein staining method. The chromosome compositions of four species were diploids of 2n=22, 2n=24 and 2n=26 respectively. The chromosomes were relatively small and showed gradual length degradation from $2.50\;{\mu}m$ to $2.16\;{\mu}m$ in Cucumis sativus, $3.71\;{\mu}m$ to $2.11\;{\mu}m$ in Cucumis melo, $3.20\;{\mu}m$ to $2.40\;{\mu}m$ in Citrullus lanatus and $3.17\;{\mu}m$ to $1.97\;{\mu}m$ in Luffa cylindrica. The chromosome types consisted of all metacentrics in Cucumis sativus, seven pairs submetacentrics and five pairs metacertrics in C. melo, four pairs of submetacentrics and seven pairs metacertrics in Citrullus lanatus, and two pairs submetacentrics and eleven pairs metacentrics in Luffa cylindrica (L.) Roemer.. The satellites were found in a pair of chromosomes in C. melo and two pairs in Luffa cylindrica. The chromosome compositions in these four species showed species-specific patterns and seemed to provide useful informations for breeding and molecular cytogenetic works on Cucurbitaceae.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.869-876
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• 2015

Wild relative species of domesticated crops are useful genetic resources for improving agronomic traits. Cytogenetic investigations based on chromosome composition provide insight into basic genetic and genomic characteristics of a species that can be exploited in a breeding program. Here, we used FISH analysis to characterize the ploidy level, chromosome constitution, and genomic distribution o f 5S and 4 5S r ibosomal DNA (rDNA) in four wild Cucurbitaceae species, namely, Citrullus lanatus (Thunb.) Mansf. var. citroides L. H. Bailey (2n = 22), Melothria japonica Maxim. (2n = 22), Sicyos angulatus L. (2n = 24), and Trichosanthes kirilowii Maxim. (2n = 66, 88, 110 cytotypes), collected in different areas of Korea. All species were diploids, except for T. kirilowii, which included hexa-, octa-, and decaploid cytotypes (2n = 6x = 66, 8x = 88, and 10x = 110). All species have small metaphase chromosomes in the range of $2-5{\mu}m$. The 45S rDNA signals were localized distally compared to the 5S rDNA. C. lanatus var. citroides and M. japonica showed one and two loci of 45S and 5S rDNA, respectively, with co-localization of rDNA signals in one M. japonica chromosome. S. angulatus showed two co-localized signals of 5S and 45S rDNA loci. The hexaploid T. kirilowii cytotype showed five signals each for 45S and 5S rDNA, with three being co-localized. This is the first report of hexaploid and decaploid cytotypes in T. kirilowii. These results will be useful in future Cucurbitaceae breeding programs.

• Journal of Apiculture
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• v.33 no.4
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• pp.239-250
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• 2018

We investigated the pollination activity of honeybees (Apis mellifera L.) in terms of different climatic conditions in the greenhouse cultivation of watermelons (Citrullus lanatus L.) during winter. The aim of the study was to search a climatic condition which effectively can be use honeybees as pollinators during the flowering season of watermelons in winter or early spring. The average climatic conditions inside the greenhouse during the bee activity time (BAT)-between 10:00 and 16:00 in mid-Februarywere a temperature of $30.4^{\circ}C$, relative humidity of 53.7%, illuminance level of 22,728.4lx, and UV level of $0.233mW/cm^2$. Bee traffic and foraging activity were at their greatest at 10:00 and tended to decrease with time. Male watermelon flowers typically dehisced between 10:00 and 12:00. Climatic conditions were significantly correlated with bee activities, including bee traffic and foraging activity. Bee activities were positively correlated with temperature, illuminance level, and UV level but negatively correlated with relative humidity. Temperature had the greatest effect on honeybee behavior. Among the foraging honeybees, the number of high-flying bees that did not pollinate flowers showed a strong positive correlation with temperature, and the number of bees landing on the flowers showed a positive correlation with the UV level. The temperature range inside greenhouses at which the pollination activities of honeybees can be maintained efficiently during winter watermelon pollination was found to be $21{\sim}25^{\circ}C$.

• Proceedings of the Korean Society of Life Science Conference
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• 2006.09a
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• pp.40.2-40.2
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• 2006

• Horticultural Science & Technology
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• v.33 no.1
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• pp.93-105
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• 2015

This study was performed to analyze genetic relationships of the four major cucurbitaceous crops including watermelon, melon, cucumber, and squash/pumpkin. Among 120 EST-SSR primer sets selected from the International Cucurbit Genomics Initiative (ICuGI) database, PCR was successful for 51 (49.17%) primer sets and 49 (40.8%) primer sets showed polymorphisms among eight Cucurbitaceae accessions. A total of 382 allele-specific PCR bands were produced by 49 EST-SSR primers from 24 Cucurbitaceae accessions and used for analysis of pairwise similarity and dendrogram construction. Assessment of the genetic relationships resulted in similarity indexes ranging from 0.01 to 0.85. In the dendrogram, 24 Cucurbitaceae accessions were classified into two major groups (Clade I and II) and 8 subgroups. Clade I comprised two subgroups, Clade I-1 for watermelon accessions [I-1a and I-1b-2: three wild-type watermelons (Citrullus lanatus var. citroides Mats. & Nakai), I-1b-1: six watermelon cultivars (Citrullus lanatus var. vulgaris S chrad.)] a nd C lade I -2 for melon and cucumber accessions [I-2a-1 : 4 melon cultivars(Cucumis melo var. cantalupensis Naudin.), I-2a-2: oriental melon cultivars (Cucumis melo var. conomon Makino.), and I-2b: five cucumber cultivars (Cucumis sativus L.)]. Squash and pumpkin accessions composed Clade II {II-1: two squash/ pumpkin cultivars [Cucurbita moschata (Duch. ex Lam.)/Duch. & Poir. and Cucurbita maxima Duch.] and II-2: two squash/pumpkin cultivars, Cucurbita pepo L./Cucurbita ficifolia Bouche.}. These results were in accordance with previously reported classification of Cucurbitaceae species, indicating that watermelon EST-SSRs show a high level of marker transferability and should be useful for genetic study in other cucurbit crops.

• Korean Journal of Plant Tissue Culture
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• v.21 no.4
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• pp.239-246
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• 1994

The genotypic (2n, 3n, 4n) response of watermelon in vitro shoot tip culture was evaluated. Different genotypes had similar response in terms of shoot formation and growth. Shoot formation was better at lower concentration of 0.3 mg/L BA and higher concentration of 5-10.0 mg/L 2iP and kinetin, but growth of newly formed shoot was inhibited. With further subculture, kinetin did not promote shoot formation Better shoot formation was observed at 0.3-0.5 mg/L BA. Combination of 0.3 mg/L BA and 0.3-0.5 mg/L BA was effective in shoot multiplication, growth and induction of more internodes. Varrying levels of light intensity and agar concentration did not affect the performance of tetraploid plants. Higher light intensity and agar concentrations decreased the number of shoot formed in triploid plane. Growth in both genotype, however was inhibited. Higher light intensity was found to promote leaf senescence in all genotypes. All growth inhibitors decreased the number of shoots formed and slowed plant growth there by prolonging duration of cultures. Growth inhibitors were to observed to decrease incidence of hyperhydricity in culture. No difference in shoot formation was observed in each of the concentrations used in Ancymidol, TIBA, CCC and PP333. Shoot formation and growth was more inhibited in ABA treatments. Leaf expansion and growth was poor in all treatments.

• Korean journal of applied entomology
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• v.40 no.2
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• pp.149-153
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• 2001

We surveyed on the host plants of Fungus gnat, Bradysia app. and found 21 species in the greenhouse and field. These are as follows: Cucumis sativus L., Cucumis melo L., Citrullus lanatus T., Cucurbita moschata F., Lycopersicon esculentum M., Capsicum annuum L (Pepper), Capsicum annuum L (Paprika), Lillium longiflorum T., Dianthus caryophyllus L., Rosa hybrida H., Gerbera jamesonii B., Chrysanthemum morifolium R, Phalaenopsis schilleriane R., Gladiolus grandiflours H., Zingiber officinale R., Cnidium officinale M., Canavalia gladiata DC., Angelica utilis M., Polygonatum odoratum D., Pinus densiflora S., and Pinus thunbergii P. Fungus gnat larvae cause damages to the root and promote decay and wilt by feeding on the roots and burrowing in plant tissue.

• Journal of Plant Biotechnology
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• v.45 no.3
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• pp.242-249
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• 2018

This study was conducted to develop an SNP set that can be useful for marker-assisted breeding (MAB) in watermelon (Citrullus. lanatus L) using Genotyping-by-sequencing (GBS) analysis of 20 commercial elite watermelon inbreds. The result of GBS showed that 77% of approximately 1.1 billion raw reads were mapped on the watermelon genome with an average mapping region of about 4,000 Kb, which indicated genome coverage of 2.3%. After the filtering process, a total of 2,670 SNPs with an average depth of 31.57 and the PIC (Polymorphic Information Content) value of 0.1~0.38 for 20 elite inbreds were obtained. Among those SNPs, 55 SNPs (5 SNPs per chromosome that are equally distributed on each chromosome) were selected. For the understanding genetic relationship of 20 elite inbreds, PCA (Principal Component Analysis) was carried out with 55 SNPs, which resulted in the classification of inbreds into 4 groups based on PC1 (52%) and PC2 (11%), thus causing differentiation between the inbreds. A similar classification pattern for PCA was observed from hierarchical clustering analysis. The SNP set developed in this study has the potential for application to cultivar identification, F1 seed purity test, and marker-assisted backcross (MABC) not only for 20 elite inbreds but also for diverse resources for watermelon breeding.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.529-534
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• 2010

Occurrence of wilted symptom in watermelon plant ($Citrullus$ $lanatus$ L.) is known to be caused by physiological disorder. The symptom results in the loss of fruit production and thus the economical loss of watermelon growers. The incidence of symptom is often found from the middle of March to the end of May in the major watermelon crop production areas of Korea (i.e. Uiryeong, Gyeongnam (lat $37^{\circ}$56'64"N, long $126^{\circ}$99'97"E)). Despite of extensive information about the physiological disorder, little study has been conducted to understand a relationship between the wilted symptom and accompanying environment factors (e.g. temperature). This study aimed to investigate effects of environmental conditions amended by a forced-ventilation system on physiological characteristics of watermelon and incidence of the wilted symptom. Watermelon plants were grown from January to May, 2009 with either the forced-or natural-ventilation treatment in a greenhouse located in the Uiryeong. In the result, the forced-ventilation treatment decreased the air, leaf and root-zone temperature approximately $4.5^{\circ}C$, $5^{\circ}C$ and $3^{\circ}C$, respectively, compared to the natural-ventilation. The fruit growth rate was maximized twice during the entire growing period. The higher rate of fruit growth was observed under the natural-ventilation than the forced one. Maximization of the fruit growth rate (approximately 430 g per day) was first observed by 12 days after fruiting under the natural-ventilation treatment, while the second one (approximately 350 g per day) was observed by 24 days after fruiting. The wilted symptom started occurring by 22 days after fruiting under the natural-ventilation, whereas no incidence of the symptom was found under the forced-ventilation treatment. Interestingly, the forced-ventilation lowered the fruit growth rate (approximately 320 g per day) compared to the natural one. Maximization of the fruit growth rate under the forced-ventilation was found at 4 days later than that under the natural one. This result coincided with a slower plant growth under the forced-ventilation treatment. These results suggest that the forced-ventilation slows down extension growth of fruit and plant, which may be associated with lowering leaf temperature and saturation deficit. We suggest the hypothesis that the forced-ventilation may alleviate stress of the wilted symptom by avoiding extreme water evaporation from leaves due to high temperature and thus by reducing competition between leaves and fruits for water. More direct and detailed investigations are needed to confirm the effect of the forced ventilation.