• The Plant Pathology Journal
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• v.16 no.4
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• pp.211-215
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• 2000

Symptoms on 4 varieties of watermelons inoculated with watermelon mosaic potyvirus II isolated from watermelon (WMV-W) were severe mosaic and leaf malformation while those inoculated with cucumber green mottle mosaic tobamovirus from watermelon (CGMMV-W) were mild mosaic and chlorotic spots. Inoculation of the mixture of WMV-W and CGMMV-W produced extremely severe mosaic along with necrotic spots and general necrosis. Doubly infected plants were also stunted. Cells infected with WMV-W or CGMMV-W alone exhibited the intrinsically ultra-structural properties of each virus infection. WMV-W induced potyvirus-characteristic cylindrical inclusions in the cytosol. Virus particles were orderly aligned along the tonoplasts. CGMMV-W induced tobamovirus-characteristic stacked crystalline arrays of virus particles in the cytosol. Cells infected doubly with WMV-W and CGMMV-W contained striking cytopathic effects that were not present in single infection of each virus. The unique ring structure, nonagon, was that a single potyvirus particle was surrounded by 9 CGMMV-W tobamovirus particles.

• The Plant Pathology Journal
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• v.16 no.4
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• pp.216-221
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• 2000

Mixed infection of watermelon mosaic potyvirus II isolated from pumpkin (WMV-P) and cucumber green mottle mosaic tobamovirus from watermelon (CGMMV-W) caused extremely severe symptoms such as progressive silting and death of watermelon plants. Single infections of either WMV-P or CGMMV-W on the same hosts produced only vein clearing and/or mosaic on the upper leaves. In cells infected with WMV-P, potyvirus-characteristic inclusions of pinwheels, scrolls and cylindrical inclusions were present in the cytosol. Parallel arrays of virus particles in the tonoplast were also common. In cells infected with CGMMV-W, virus particles occurred as stacked-bands of scattered randomly in the cytosol and vacuoles in all type cells. Many cells also contained vesiculated mitochondria with fibril-containing vesicles. Cells infected mixedly with WMV-P and CGMMV-W contained structural features that were not observed in cells infected singly with the two viruses. A particle of WMV-P potyvirus was surrounded by evenly spaced nine particles of CGMMV-W tobamovirus, which made a unique nonagon ring. The angled layers having $60^{\circ}$-$135^{\circ}$ were alternating layer, herringbone, crosshatching and ladder figures.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.175-180
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• 1994

The fungal pathogen Monosporascus annonballus was first isolated in Korea from the rotted roots of bottle gourd stocks of collapsed watermelon plants in fields near Chochiwon, Choongnam province in July, 1993. Perithecia of M. cannonballus were dark brown to black, globose, 220~570 ${\mu}{\textrm}{m}$ in diam. and had many asci. Asci are hyaline, clavate to pyriform, and 50~120$\times$35~570 ${\mu}{\textrm}{m}$ in size. Ascospores were aseptate, dark brown to black, globose, 25~45$\times$30~50 ${\mu}{\textrm}{m}$ in diam, and borne singly in each ascus. The fungus grew in the temperature range of 4 to 34$^{\circ}C$, best at 3$0^{\circ}C$. The optimum pH for growth was 6.8. Mycelial growth rate of M. cannonballus was 25.5mm/day on PDA at 26$^{\circ}C$. Perithecia began to form after 20-day-growth on PDA and produced mature asci after 30 days or later. In the greenhouse inoculation tests, the fungus developed water-soaked lesions on roots of bottle gourd seedlings and was then reisolated from the lesions. Severed damages on watermelon plants by M. cannonballus are greatly concerned in Korea, since no stocks used for watermelon cultivation have reported to be resistant to the fungus.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1233-1239
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• 2014

Watermelon (Citrullus vulgaris L.) is a summer fruit typical to help fatigue systemic absorption is getting better. The goal of this study is to screen antioxidant activity to ensure the possibility as a functional material for exocarp of watermelon. Watermelon was extracted with 70% methanol, 70% ethanol, chloroform:methanol (CM, 2:1, v/v). Total phenol contents were 12.01 mg/g, 8.89 mg/g, 3.53 mg/g in the 70% methanol, 70% ethanol, CM, in that order, respectively. Total flavonoid content, DPPH radical scavenging activity, ABTS radical scavenging activity, ferric reducing antioxidant power (FRAP), ${\beta}$-carotene bleaching assay were 70% methanol extract remarkably higher than the other extracts. And these results showed the same trend of total phenol content. From the above results shows that watermelon was effective on the antioxidative activity.

• The Plant Pathology Journal
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• v.19 no.4
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• pp.200-202
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• 2003

Leaf spots were first observed on watermelon (Citrullus vulgaris Schrad) under polyethylene film-covered green-house in November 2002. Symptoms appeared as dark-brown circles or large irregular spots on the leaves of watermelon. Occasionally, zonal growth of the lesions was observed. Under humid conditions, small black sclerotium-like bodies (sporodochia) were produced on the surface of the lesions. The sporodochia on leaf lesions were sessile, polymorphic, variable in size, 35-850 $\mu\textrm{m}$ in diameter, and 30-470 $\mu\textrm{m}$ in depth. Conidia in sporodochium were black in mass, one-celled, rod-shaped, with rounded ends, hyaline, guttulate, and measured 6-8$\times$1.6-2.2 $\mu\textrm{m}$ in size. The pathogen was identified as Myrothecium roridum Tode ex Fr. This is the first report of Myrothecium leaf spot on watermelon naturally occurring in commercial greenhouses.

• Research in Plant Disease
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• v.10 no.1
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• pp.39-43
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• 2004

Recent occurrence of virus diseases on watermelon plants cultivated in Jeonnam province was investigated from 1998 to 2002. While virus diseases were severely occurred on watermelon cultivated in green house in 1998, those of open field were severer than in green house since 2000. When 128 samples collected from different fields were examined by electron microscopy, 87.8％ of the samples contained rod-shaped or filamentous virus particles. RT-PCR analysis of the samples revealed that Cucumber green mottle mosaic virus (CGMMV) was only detected from collected samples at May. Watermelon mosaic virus (WMV) was most frequently found and CGMMV and Zucchini yellow mosaic virus (ZYMV) were slightly at June and July. However Cucumber mosaic virus (CMV) and Papaya ringspot virus (PRSV) have not been detected.

• The Plant Pathology Journal
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• v.36 no.1
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• pp.29-42
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• 2020

Acidovorax citrulli causes bacterial fruit blotch in Cucurbitaceae, including watermelon. Although A. citrulli is a seed-borne pathogen, it can cause diverse symptoms in other plant organs like leaves, stems and fruits. To determine the infection routes of A. citrulli, we examined the virulence of six isolates (Ac0, Ac1, Ac2, Ac4, Ac8, and Ac11) on watermelon using several inoculation methods. Among six isolates, DNA polymorphism reveals that three isolates Ac0, Ac1, and Ac4 belong to Clonal Complex (CC) group II and the others do CC group I. Ac0, Ac4, and Ac8 isolates efficiently infected seeds during germination in soil, and Ac0 and Ac4 also infected the roots of watermelon seedlings wounded prior to inoculation. Infection through leaves was successful only by three isolates belonging to CC group II, and two of these also infected the mature watermelon fruits. Ac2 did not cause the disease in all assays. Interestingly, three putative type III effectors (Aave_2166, Aave_2708, and Aave_3062) with intact forms were only found in CC group II. Overall, our results indicate that A. citrulli can infect watermelons through diverse routes, and the CC grouping of A. citrulli was only correlated with virulence in leaf infection assays.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2004.10a
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• pp.62-65
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• 2004

To protect the watermelon against soil-borne pathogens, we are currently producing disease-resistant transgenic root stock for the growth of watermelon, A defensin gene (J1-1) from Capsicum annum, a ACC deaminase gene from Pseudomonas syringae, a galactinol synthase (CsGolS) gene from Cucumis sativus, and a WRKY (CvWRKY2) gene from Citullus vulgaris were used as transgenes for disease resistance. The gene were transformed into a inbred line (6-2-2) of watermelon, Kong-dae watermelon and a inbred line (GO702S) of gourd, respectively, by Agrobacterium-mediated transformation. Putative transgenic plants were selected in medium containing 100mg/L kanamycin, and then integration of the genes into the genomic DNA were demonstrated by PCR analysis. Successful integration of the gene in regenerated plants was also confirmed by PCR (Figf 1), genomic Southern blot (Fig 2), RT-PCR (Fig 3), and Northern blot analysis(Fig 4). Several T1 lines having different transgene were produced, and disease resistance of the T1 lines are under estimation.

• Animal cells and systems
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• v.9 no.2
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• pp.75-78
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• 2005

Fungicides and antagonists were tested for their efficacy in the management of fungal pathogens of watermelon. The fungal species in different genera were isolated from the seeds of watermelon and their vulnerability was assessed against an array of chemicals and bioagents. Among the fungal pathogens, Fusarium species were effectively controlled by Bavistin. Topsin also showed the promising effects against all the fungal pathogens, and Dithane M-45 effectively controlled Didymella bryoniae. Seed treatment with antagonists like Trichoderma harzianum and T. viride improved the seed germination, seedling vigour and reduced the incidence of seed-borne fungal pathogens. Bavistin and Topsin among chemicals increased significantly the seed germination and vigour index. Trichoderma harzianum showed its efficacy against all Fusarium species and even stood effective than Captan and Blitox. However, Pseudomonas fIuorescens also showed promising effect against Didymella bryoniae over fungicides. Under field condition, Topsin and Dithane M-45 showed better yield than Bioagents.

• Journal of Plant Biotechnology
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• v.6 no.4
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• pp.247-252
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• 2004

In vitro cultures of watermelon were treated with antimitotic agent colchicine to induce ploidy alterations, particularly the induction of tetraploids. Explants cotyledon, embryonic end of seed, transverse sections of epicotyl and hypocotyl were cultured on MS media supplemented with BA ($1{\mu}M$) and colchicine ($0.01\%,\;0.05\%\;and\;0.1\%$). Explants were subcultured on colchicine free media after 4 and 7 days. Colchicine had negative effect on in vitro regeneration but this exhibited explants related response. However, hypocotyl section of seedlings induced maximum callus on $0.01\%$ colchicine. Shoot proliferation was more in cotyledon explants cultured on colchicine ($0.01\%$) for four days. Maximum root induction and root number were recorded in embryonic end explants. Overall, cotyledon and embryonic end explants, and low colchicine concentration ($0.01\%$) was found optimal in watermelon regeneration.