• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.330-337
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• 1995

Forty-six isolates of Fusarium oxysporum collected from infected tomato plants and soils in greenhouses in Sedo, Chungnam and Angang, Kyeongbuk and 8 isolates of F. oxysporum f. sp. lycopersici from Japan and USA were used to determine vegetative compatibility groups (VCGs). Vegetative comaptibility was assessed on the basis of heterokaryon formation among nitrate nonutilizing mutants. All Korean isolates of F. oxysporum f. sp. lycopersici used in this study belonged to the same type of VCG (003) regardless of their geographic origin, cultivar and race, but they were incompatible with the foreign isolates of VCG 0030, 0031, 0032 and 0033. Based on the results, the Korean isolates of F. oxysporum f. sp. lycopersici were classified as a new VCG 003.

• The Plant Pathology Journal
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• v.19 no.6
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• pp.269-273
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• 2003

A total of 57 isolates of Colletotrichum gloeosporioides were recovered from diseased tissues of Hall's crab apple (Malus haliana), 3 cultivars of edible apple (M. pumila var. dulcissima), red pepper (Capsicum annum), and grapevine (Vitis vinifera) fruits. All isolates showed strong virulence on their own host plants. Isolates from edible apple exhibited high level of cultivar specificity in pathogenicity tests. Ten isolates from apple cultivar 'Fuji' were virulent on 'Jonathan' and 'Rall's Genet'. However, 12 isolates from 'Jonathan' and 'Rall's Genet' were not virulent on 'Fuji'. Among the 24 isolates from red pepper, only seven and two isolates were infective on edible apple and grapevine fruits, respectively. All six isolates from grapevine were only virulent on their own host. These isolates were grouped into five vegetative compatibility groups (VCGs), A, B, C, D, and E, by demonstrating heterokaryosis through complementation using nitrate-nonutilizing (nit) mutants. Among them, isolates belong to VCG-A and VCG-D accounted for 24 and 17 isolates； those in VCG-A exhibited wide host range involving Hall's crab apple, all three edible apple cultivars, and red pepper. On the other hand, isolates of VCG-D and VCG-E showed limited host range specific to red pepper and grapevine, respectively. Taken together, the data suggest that among C. gloeosporioides isolates, the concepts of pathotype and/or forma specialis may exist, and that three is a relationship between host specificity and VCG grouping among C. gloeosporioides isolates.

• The Plant Pathology Journal
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• v.26 no.3
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• pp.216-222
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• 2010

Fusarium proliferatum is the causal agent of stalk and root rot disease of maize, foot rot disease of rice, basal and root rot disease of onion and knife cut disease of sugarcane in Iran. In recent years, incidence and severity of these diseases have been increased in Iran. Fifty seven F. proliferatum single-spore isolates collected from diseased maize, rice, onion and sugarcane plants at different areas were used to study genetic diversity by determination of vegetative compatibility groups (VCGs). Chlorate-resistant nitrate non-utilizing (nit) mutants were recovered from selected isolates of F. proliferatum and used in complementation tests. All isolates in which both nit1 and NitM (or nit3) mutants were recovered, demonstrated self-compatibility. Vegetative compatibility tests by pairing nit mutants identified 30 VCGs among 57 isolates. Twenty-three isolates belonged to singlemember VCGs and the remaining 34 isolates, belonged to other seven multimember VCGs. Segregation of F. proliferatum isolates obtained from various area and host plants into different VCGs in Iran is reported for the first time. In this study, none of isolates obtained from rice complemented with any other isolates from onion and sugarcane and, non complementation occurred between onion and sugarcane isolates. Also, only one complementation occurred between one isolate of maize and one isolate of sugarcane and rice. Thus, a correlation between VCGs grouping and host preferences was founded. It is concluded that natural populations of F. proliferatum in Iran are probably genetically divergent and include isolates representing a potential risk for disease development.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.171-176
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• 2011

Sclerotinia homoeocarpa, the causal agent of dollar spot, is one of the most common pathogens of cool season turfgrasses in South Korea. The vegetative compatibility group (VCG) assay was carried out using nitrate-nonutilizing (nit) mutants recovered from 13 South Korean isolates with various geographical origins. The mutants were divided into four phenotypic classes based on mutation loci associated with nitrogen assimilation: nit1, nit2, nit3, and NitM. The recovered number of nit mutants greatly varied among the isolates, ranging from 0 to 15 mutants. Of the mutants isolated, nit1 and nit2 mutants were most common (80%) while NitM and nit3 were relatively rare. One dominant and four minor VCGs were determined from 18 mutant isolates tested. To study population structures of Korean S. homoeocarpa isolates and increase our understanding of its ecological and epidemiological aspects for dollar spot management on turfgrass, more generated mutants should be tested with more diverse isolate collections.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.23-23
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• 2003

Chestnut blight, caused by Cryphonectria parasitica, is the most destructive disease of American and European chestnut trees. A total of 672 C prasitica was isolated from blight lesion on chestnut twigs, which were collected from major chestnut plantations all over Korea in 1999. Isolation rates were over 30% in Kyunggj-, Kyongnam-, and Chonnam-do. The highest isolation rate was 37.4% and recorded in Kyongnam-do. On the other hand, Chonbuk-do had the lowest isolation rate as 13.5%. In grouping of C parasitica by colony shape and color, yellow colony with irregular margin were the most dominant colony type with a frequency of 65.2%. When the 672 isolates were inoculated on the chestnut twigs, 380 isolates (56.5%) caused lesions larger than the standard virulent isolate EP155-2, while 158 isolates (23.4%) caused smaller lesions than the standard hypovirulent isolate UEP-1. In Bavendamm test that determines phenol oxidase activity, 97.1% of all the isolates resulted the same or darker discoloration than EP155-2, and only 12.2% resulted the same or lighter discoloration than UEP-1. In the vegetative compatibility (VC) tests, total 670 isolates were divided into 121 VC groups (VCGs). Kyongnam-, Chonnam-, and Chungnam-do, the three principal chestnut plantation area, had 49, 33, and 27 VCGs, respectively. Among the VCGs, the biggest VCG, KR-VC104, was composed of 164 isolates and the second biggest VCG had 62 isolates. But, 64 of 121 VCGs consisted of sole member. More than 65.8% of KR-VC104, was isolated from the three provinces, Kyongnam-, Kangwon-, and Chungbuk-do. In KR-VC104, 62.8%, 59.1%, and 85.9% of the isolates looked like virulent in colony type, pathogenicity test, and Bavendamm test. In ds-RNA detection tests using cellulose chromatography, 77 of total 650 isolates were ds-RNA positive and detected ds-RNA segments were approximately 12kb, 3kb, 2.7kb, 2kb, and 1.8kb in size. Among the 77 isolates, 46 isolates had 12kb and 25 isolates had 12kb and 2.7kb. Other 6 Isolates had small ds-RNA segments. Kyongnam-, Chonnam-, and Chungnam-do had 43, 16, and 5 ds-RNA positive isolates, respectively. Among the 121 VCGs, only 29 VCGs had ds-RNA positive isolates.(중략)