• Research in Plant Disease
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• v.17 no.2
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• pp.161-168
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• 2011

To establish simple and reliable screening method for resistant radish to Plasmodiophora brassicae Woron. using soil-drenching inoculation, the development of clubroot on radish seedlings inoculated with P. brassicae GN-1 isolate according to several conditions such as inoculum concentration, plant growth stage and incubation period after inoculation was studied. To select resistant radish against clubroot, 10-day-old seedlings were inoculated with P. brassicae by drenching the roots with the spore suspension of the pathogen to give $1{\times}10^9$ spores/pot. The inoculated seedlings were incubated in a growth chamber at $20^{\circ}C$ for 3 days then cultivated in a greenhouse ($20{\pm}5^{\circ}C$) for 6 weeks. Under the optimum conditions, 46 commercial cultivars of radish were tested for resistance to YC-1 (infecting 15 clubroot-resistant cultivars of Chinese cabbage) and GN-1 (wild type) isolates of P. brassicae. Among them, thirty-five cultivars showed resistance to both isolates and one cultivar represented susceptible response to the pathogens. On the other hand, the other cultivars showed different responses against the tested P. brassicae pathogens. The results suggest that this method is an efficient system for screening radish with resistance to clubroot.

• Journal of Plant Biotechnology
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• v.43 no.1
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• pp.58-65
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• 2016

Powdery mildew is an important disease of the melon (Cucumis melo L.). Seven isolates of powdery mildew fungi were collected from five locations in Korea; Anseong (DH487), Icheon (BN103, BN625, BN968), Yeongam (YA141), Changnyeong (CN582), and Suncheon (SN102). All 7 fungi had a similar trend of conidial chain and conidiophore development as Podosphaera xanthii with fibrosin bodies in mature conidia. Among them, 2 isolates of powdery mildew fungi; CN582 and SN102 showed similar responses to resistance against powdery mildew as the previously reported race 1 and race N2. The isolates YA141 and BN103 showed similar responses as like as race A. However, three isolates of powdery mildew fungi (BN625, BN968, and DH487) showed different responses compared to the previously reported races (1, N1, N2, A, S, and 5). Therefore, these three isolates could be designated as new races in melon. Nine out of 15 commercial melon cultivars in Korea showed resistance to race 1 (CN582). However, the new race BN968 invaded all 15 cultivars. Results of the two molecular markers were consistent in response to disease development by race 1 of Podosphaera xanthii in case of the above mentioned cultivars. This study confirmed the presence of new melon powdery mildew fungi in Korea which are similarly notorious as like as the previously reported race 1. Therefore, breeders can use these two molecular markers for breeding melon in Korea that is resistant to race 1 and as well as to some other races.

• Korean journal of applied entomology
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• v.14 no.1 s.22
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• pp.13-21
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• 1975

Experiments were conducted to select the new varieties and or/lines of rice resistant to the green rice leafhopper, Nephotettix cincticeps Uhler, and to evaluate the nature of their resistance to the insects in connection with the antibiosis and feeding and ovipositional preferences. The materials tested in this study were the varieties and or/lines of rice mostly proposed by the International Insect Resistance Nursery of IRRI and some others also orginiated from IRRI. Out of the 48 varieties and or/lines the 9 were selected as resistant and the 11 as mderately resistant. They have high antibiosis to the insects, showing significantly higher nymphal mortality and less adult emergence in the resistant and moderately resistant ones than the susceptible and moderately susceptible varieties Jinheung and Tong-il. Feeding perference was significantly different between the resistant and susceptible rice plants, resulting in much lower on resistant ones and much higher on susceptible ones. Ovipositional preference, however, was not different at all between the resistant and the susceptible ones. The nature of varietal resistance of rice to the green rice leafhopper seemed to be surely associated with the antibiosis and non-feeding preference.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.673-683
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• 2014

This study was conducted to establish an efficient screening method to identify cucurbits resistant to powdery mildew. Powdery mildew fungus was obtained from a single lesion of infected cucumber leaf in 2010 at Daejeon. The fungus was identified as Podosphaera xanthii race 1 based on morphological characteristics and resistance responses of four melon differentials. Development of powdery mildew caused by the fungal isolate on 34 commercial cultivars of cucumber was investigated at three plant growth stages in a greenhouse. The degree of resistance of cotyledons of each cultivar to the fungus was not correlated with that of whole plant, but powdery mildew occurrence in the first true leaf was highly correlated with resistance at the level of the whole plant. Based on these results, the first true leaf of cucurbit cultivars can be used for screening of resistance to powdery mildew. In addition, variation of resistance of commercial 12 cucumber and 26 melon cultivars to the powdery mildew fungus due to different growing seasons was tested. In the case of cucumber, the resistance response in some cultivars was influenced by growing season. The resistant cultivars showed higher resistance in the warm season than in the cool season. By contrast, the resistant melon cultivars demonstrated strong resistance in all the tested growing seasons. Interestingly, the tested powdery mildew pathogen, a member of P. xanthii race 1, was not pathogenic on seven cultivars of watermelon (Citrullus lanatus). To follow up on this, diverse race 1 isolates of P. xanthii should be collected and tested.

• Korean Journal Plant Pathology
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• v.2 no.3
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• pp.199-206
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• 1986

Penetration level, female development and histological changes in infected root tissues were investigated following inoculation with different inoculum levels (110,440 and 1760 juveniles/plant) of Heterodera glycines (SCN) race 3 on susceptible 'Lee' and resistant 'Pickett' soybean cultivars. Penetration level was lower in Pickett at the higher inoculum levels but no differences were detected in Lee. However, the lower penetration level in the resistant soybean cultivar appeared not to be directly related to plant resistance (female maturation). The number of females recovered from Lee was lower at the highest inoculum level. The number of females maturing on Pickett was much less than that on Lee, showing that changes of SCN population is associated with the number of SCN maturing rather than nematode penetration. In Lee mono-infection sites (a single nematode per site) syncytia had dense cytoplasm and no central vacuoles. while multi-infected sites (many overlapping nematodes per site) had syncytia with a large central vacuole and many small vacuoles. Resistant responses in mono-and multi-infected root tissues of Pickett were delayed and rapid necrosis, respectively. The differences in tissue response are suggested as a mechanism that controls density-dependent population changes in resistant and/or susceptible soybean cultivars.

• Research in Plant Disease
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• v.10 no.2
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• pp.135-137
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• 2004

It was conducted to select the resistant potato cultivars to common scab, to replace the existing susceptible cv Dejima in Jeju island conditions both 1997 and 2001. Among cultivars, cvs Jemchip, Alpa, Atlantic and Jopung were more resistant than others in the field with both low and high incidence of the disease. Also among the existing cultivars grown in Korea, cvs Superior, Jopung and Chubaek were resistant, expecially in terms of production of marketable potatoes.

• Korean journal of applied entomology
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• v.38 no.3
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• pp.249-253
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• 1999

To study races of Heterodera glycines in Korea, 21 soil samples were collected from eight provinces in 1995. Four races were found; race 3(48%) was a dominant race flowed by race 5(24%), race 1(19%), and race 6(9%). About 30~40% of H. glycines populations reproduced on Pickett and PI88788, while non reproduced on Peking or PI90763. Development of resistant soybean cultivar targeting to race 5 and 6 of H. glycines using PI90763 and PI88788 as a parent is recommended.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.4
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• pp.376-382
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• 2013

Rice sheath blight (ShB), caused by Rhizoctonia solani K$\ddot{u}$hn, is one of the serious fungal disease resulting in severe yield loss in rice field worldwide. There are limited sources of genetic resistance and no commercial cultivar with high level of ShB resistance is currently available in Korea. In order to seek available resources with high level of resistance to ShB, 40 rice germplasms were used to evaluate disease reactions including ShB, leaf blast and bacterial leaf blight and these germplasms also examined agronomic traits such as days to heading, culm length, panicle length, No. of panicles, No. of spikelets per panicle and so on. There is wide variation in agronomic characters and disease reactions. Rice germplasms also showed considerably different ShB reaction caused by inoculation at seedling stage. Areumbyeo, Gayabyeo, IR579-Es44 and IR64 showed more strong reaction to ShB than the others. Especially, Gayabyeo is considerably available to develop a new variety with resistance to ShB in Korea.

• Korean journal of applied entomology
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• v.26 no.4 s.73
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• pp.257-259
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• 1987

One thirty one varieties of Groundnut were screened for search of multiple disease resistance against rust caused by Puccinia arachidis speg. and leaf spots caused by Cereospora arachidis Hori and Phaeoisariopsis personata . Out of these, 7 were resistant, and 11 were moderatly resistant. Percent disease severity and its' effect on yield was assessed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.2
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• pp.118-125
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• 1978

To find out highly resistant gene source to black rot fungus in sweetpotato varieties, a screening test was carried out with inoculated tubers and sprouts in 1976 and 1977. Fifteen varieties out of 165 and 54 varieties out of 161 were highly resistant to black rot in the tuber and sprout tests. respectively. The sprout test showed bigger variation from year to year compared to tuber test. Varieties highly resistant to black rot in both tuber and sprout tests were Suweon # 59, #81, #90, Norin #17, #23. Chilship-il cho, Sachun Jong #36, Hamkao, and Kandee.