• The Plant Pathology Journal
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• v.21 no.4
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• pp.402-405
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• 2005

We have previously identified genes for four different protease inhibitors (PIs) that were induced upon rice blast infection in a rice blast resistant mutant SHM-11. Our expression analysis of the PIs indicated that induction of the PIs was the highest 24 hr after rice blast inoculation in the rice mutant SHM-11. Three PIs in the group of serine PIs were highly expressed while a cystein PI was weakly expressed upon rice blast inoculation. Four PIs were weakly induced 48 hr after pathogen inoculation in rice blast susceptible wild type rice plant. The simultaneous expression of three serine PIs was apparent from SHM-11 and two of them were induced in rice blast resistant Taebaegbyeo. One of them was induced in rice blast resistant Hwayeongbyeo while none of them were expressed in rice blast susceptible Nagdongbyeo and rice blast resistant Dongjinbyeo. Our results suggest that the expression of PI gene is rice cultivar specific and may be linked with the rice blast resistance in a specific rice mutant by the simultaneous expression of the PI genes.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.151-161
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• 2021

Fusarium wilt disease of tomato plants caused by Fusarium oxysporum f.sp. lycopersici (FOL race2) is one of the most important diseases of tomatoes worldwide. In the competition between tomato and FOL, the FOL can win by overcoming the immune system of tomato plants. Resistant interaction between the FOL race2 and tomato plants is controlled by avirulence genes (AVR2) in FOL and the corresponding resistance genes (I2) in tomato plants. In this study, 7 FOL isolates (KACC) were used to test their pathogenicity, and FOL race2 was selected because it is a broad problem in Korea. The Fol40044 isolates showed the most severe pathogenicity, and the avr2 gene was also isolated and identified. Moreover, to select resistance, 20 tomato varieties were inoculated with the Fol40044, and the degree of pathogenicity was evaluated by analyzing the expression of the avr2 gene. As a result, three resistant tomato varieties (PCNUF73, PCNUF101, PCNUF113) were selected, and the expression of the avr2 gene was much lower than that of the control Heinz cultivar. This result shows that the screening assay is very efficient when the avr2 gene is used as a marker to evaluate the expression level when selecting varieties resistant to tomato wilt disease. Based on these results, it is possible to isolate the I2 gene, which exhibits resistance and molecular biological interactions with the AVR2 gene from the three tomato-resistant varieties. The I2 gene provides breeders more opportunities for Fusarium disease resistance and may contribute to our understanding of their interactions with the FOL and host plant.

• The Plant Pathology Journal
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• v.38 no.1
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• pp.1-11
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• 2022

Fusarium culmorum is one of the most important causal agents of root rot of wheat. In this study, 10 F. culmorum isolates were collected from farms located in five agro-ecological regions of Morocco. These were used to challenge 20 durum wheat genotypes via artificial inoculation of plant roots under controlled conditions. The isolate virulence was determined by three traits (roots browning index, stem browning index, and severity of root rot). An alpha-lattice design with three replicates was used, and the resulting ANOVA revealed a significant (P < 0.01) effect of isolate (I), genotype (G), and G × I interaction. A total of four response types were observed (R, MR, MS, and S) revealing that different genes in both the pathogen and the host were activated in 53% of interactions. Most genotypes were susceptible to eight or more isolates, while the Moroccan cultivar Marouan was reported resistant to three isolates and moderately resistant to three others. Similarly, the Australian breeding line SSD1479-117 was reported resistant to two isolates and moderately resistant to four others. The ICARDA elites Icaverve, Berghisyr, Berghisyr2, Amina, and Icaverve2 were identified as moderately resistant. Principal component analysis based on the genotypes responses defined two major clusters and two sub-clusters for the 10 F. culmorum isolates. Isolate Fc9 collected in Khemis Zemamra was the most virulent while isolate Fc3 collected in Haj-Kaddour was the least virulent. This work provides initial results for the discovery of differential reactions between the durum lines and isolates and the identification of novel sources of resistance.

• Korean Journal of Agricultural Science
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• v.15 no.1
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• pp.1-7
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• 1988

Out of 24 isolates of Alternaria collected from pear leaves, only 7 isolates from cv. Nijiseiki leaves were specifically pathogenic to susceptible pear cultivar(Nijiseiki). Other isolates from cv. Chojuro, Oksankichi and Sinko did not show any pathogenicity to pear leaves. Pathogenic isolates of Alternaria kikuchiana produced host-specific toxin (AK-toxin) in liquid culture which caused veinal necrosis only on susceptible pear leaves, while nonpathogenic isolates did not produce this toxin. Varietal susceptibility among pear cultivars to the pathogen was investigated by evaluating HST (AK-toxin) sensitivity of pear leaves, as a substitute for spore inoculation. AK-toxin which the fungus produces was toxic to pear cultivars susceptible to the pathogen such as Isipsegi and Sinsu, but was harmless to resistant pear cultivars such as Chojuro, Oksankichi, Niitaka etc. Changes in disease susceptibility and toxin sensitivity of pear leaves with aging was investigated. Disease susceptibility and toxin sensitivity in cv. Sinsu leaves appeared to vary with leaf aging; the young leaves were visibly susceptible, but older leaves (more than 2 week old leaves) became resistant.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.72.2-73
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• 2003

We found a soybean (Glycine max) cultivar 561 that was strongly resistant to a virulent bacterial strain of a Pseudomonas spp. Further identification revealed that the Pseudomonas spp. was a strain of Pseudomonas aeruginosa. Furthermore we identified specific genes involved in the resistance of soybean 561 and analyzed the pattern of gene expression against the Pseudomonas infection using differential-display reverse transcription PCR (DDRT-PCR). More than 126 cDNA fragments representing mRNAs were induced within 48 hours of bacteria inoculation. Among them, 28 cDNA fragments were cloned and sequenced. Twelve differentially displayed clones with open reading frames had unknown functions. Sixteen selected cDNA clones were homologous to known genes in the other organisms. Some of the identified cDNAs were pathogenesis-related genes (PR genes) and PR-like genes. These cDNAs included a putative calmodulin-binding protein, an endo-1,3-1,4-b-D-glucanase, a b-1,3-endoglucanase, a b-1,3-exoglucanase, a phytochelatin synthetase-like gene, a thiol pretense, a cycloartenol synthase, and a putative receptor-like sorineithreonine protein kinase. Among them, we found that four genes were putative pathogenesis-related genes (PR) induced significantly by the p. aeruginosa infection. These included a calmodulin-binding protein gene, a b-1,3-endoglucanase gene, a receptor-like sorine/threonine protein kinase gene, and pS321 (unknown function). These results suggest that the differentially expressed genes may mediate the strong resistance of soybean 561 to Pseudomonas aeruoginosa.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.296-301
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• 1999

The concerns on the crop damage by ultraviolet (UV) radiations is increasing owing to the decrease of their absorbing stratospheric ozone in the tropospheric. Cultivar differences on early growth of UV radiation among five Korean rice cultivars, four japonica types and one Tongil type (indica-japonica cross hybrid), were studied. Pot-seeded rice plants were grown under four different radiation conditions, i.e., visible radiation only, visible radiation with supplemented with high or low dose of UV-B (280~320 nm in wavelength) and UV-C (less than 280 nm in wavelength). The inhibitory degree on plant height, shoot and root weight and length of leaf blade and leaf sheath were determined at 40 days after seeding. UV-C showed the most severe inhibitory effect on the degree of biomass gain and leaf growth in most cultivars examined, followed by high UV-B and low UV-B. Among the cultivars used, the Kuemobyeo was the most sensitive cultivar and had not repair or showed resistance ability to continued irradiation of UV radiation. However, Janganbyeo and Jaekeon showed different responses that the elongation of leaf blades was promoted on 2nd and 3rd leaves and inhibited on 4th and 5th leaves but this inhibitory degree was reduced on 6 th and 7th leaves. Such tendency on leaf growth means that both cultivars had low sensitivity and most resistant ability to continued irradiation of UV radiation. While Tongil showed different response to enhanced UV radiation, ie., low UV-B promoted leaf growth but the inhibitory was severely increased by continued irradiation of high UV-B and UV-C, which means that Tongil had high threshold of UV radiation for response as an inhibitory light of plant growth. The results of this study indicate that the differences on sensitivity or resistant to the effects of UV radiation were existed among Korean rice cultivars.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.5
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• pp.73-81
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• 2020

One of the most important vegetables consumed in Korea, chili peppers (Capsicum annuum) are widely cultivated around the world. Chili peppers have been severely damaged by anthracnose during their growth, so it is important to study prevention and resistance varieties. K1 anthracnose was inoculated against four cultivar of chili peppers that are resistant to anthracnose and one cultivar that is sensitive. The area of the disease that appeared over time was photographed and quantified through the program was analyzed. Through the ratio of the area of chili pepper fruit and the area of the bottle, the sensitive variety An-S showed weak reactions to anthracnose with about 40%, the resistant variety An-12R (23%), An-Tan (21%), and An-9R (19%), and PBC81 showed a strong response to anthracnose with about 11%. These quantitative value can be used as a basis for comparison in conducting resistance studies for new varieties.

• Research in Plant Disease
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• v.9 no.2
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• pp.79-84
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• 2003

A wilt disease of commercial cyclamen (Cyclamen persicum) which grown in greenhouse was found in Gyeo-nggi province of Korea during the period from August, 2001 to July, 2002. The disease incidence was up to 42.7% in Kimpo, Gyeonggi province. The disease was more severe in ebb and flow irrigation system than con-ventional overhead flooding\'s. The wilted cyclamen plants showed the chlorosis of leaves and followed by the death. The vascular tissues of the infected basal stem and bulb were discolored with black streaks. The casual fungus was identified to be Fusarium oxysporum f. sp. cyclaminis on the basis of mycological characteristics. Effect of infected soil showed 100% infection rate when the cyclamen plants were grown in potting with infested soil. Examine resistant cultivar showed ‘Matis red’, ‘Schubert’, ‘Victoria’ and ‘Chopin’ were the resistant cultivars but most of cultivars were susceptible to Fusarium wilt. The control effect of chemicals for cyclamen wilt was not much efficient to curative effects even though. Benomyl WP and Fludioxonil SC on the Fusarium wilt had only preventive effects by soil drenching in the pot before inoculation of F. oxysporum. This is the first report on the fusarium wilt of cyclamen caused by F. oxysporum f. sp. cyclaminis in Korea.

• 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.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.110-116
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• 2013

This study was carried out to establish the simple mass-screening methods for resistant tomato to Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL). Root dip inoculation method has been used in many studies on the resistance of tomato to disease. On the other hand, in mass-screening for resistant tomato to Fusarium wilt, the inoculation method is time-consuming and laborious procedure. Disease development of two FOL isolates on two cultivars of tomato according to inoculation method including root dip, tip and scalpel methods were investigated. In compatible interaction, tomato seedlings of each cultivar inoculated by tip method showed the lower and more variable disease severities than by root dip method. Whereas the seedlings by scalpel method represented clear resistant and susceptible responses to Fusarium wilt as root dip method. The resistance degree of each cultivar inoculated with FOL isolates by scalpel method was hardly affected by the tested incubation temperature and inoculum concentration. On the basis of the results, we suggest scalpel inoculation method as an efficient mass-screening method for resistant of tomato cultivars to Fusarium wilt. Roots of tomato seedlings at two-leaf stage grown in plastic cell tray were injured with scalpel and then spore suspension (more than $1{\times}10^7\;conidia{\cdot}mL^{-1}$) of FOL was poured directly on the roots. The infected plants were cultivated in a growth room at $25-30^{\circ}C$ for 4 weeks with 12-hours light a day.