• 한국약용작물학회지
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• 제26권4호
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• pp.302-307
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• 2018

Background: A soil-borne pathogenic fungus, Ilyonectria radicicola (Cylindrocarpon destructans) causes root rot on ginseng (Panax ginseng C. A. Meyer) and is known to attack many other plants. The Nectria/Neonectria radicicola complex has been renamed as the I. radicicola complex after analysis of its multi-gene relatedness and morphological characteristics. The fungi in this complex have been reclassified into 16 species under the genus Ilyonectria based on characteristics analysis Methods and Results: To obtain useful data from the Korean ginseng root rot, I. radicicola was isolated from the rhizosphere soils of the chestnut tree. They were identified through a pathogenicity test and a survey of the morphological features. The existence of I. radicicola in soil samples was confirmed by PCR detections using nested PCR with species-specific primer sets. These were subsequenctly isolated on semi-selective media from PCR-positive soils. Genetic analysis of the I. radicicola complex containing these pathogens was done by comparing the DNA sequences of the histone h3 region. These isolates originating from the rhizosphere soils of chestnut constituted a clade with other closely related species or I. radicicola isolates originating from ginseng or other host plants, respectively. Additionally, the pathogenicity tests to analyze the characteristics of these I. radicicola isolates revealed that they caused weakly virulent root rot on ginseng. Conclusions: This is the first study reporting that I. radicicola isolates from chestnut rhizosphere soils can attack ginseng plant in Korea. Thus, these results are expected to provide informations in the selection of suitable fields for ginseng cultivation.

• Journal of Ginseng Research
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• 제42권1호
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• pp.9-15
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• 2018

Cylindrocarpon destructans/Ilyonectria radicicola is thought to cause both rusty symptom and root-rot disease of American and Korean ginseng. Root-rot disease poses a more serious threat to ginseng roots than rusty symptoms, which we argue result from the plant defense response to pathogen attack. Therefore, strains causing rotten root are characterized as more aggressive than strains causing rusty symptoms. In this review, we state 1- the molecular evidence indicating that the root-rot causing strains are genetically distinct considering them as a separate species of Ilyonectria, namely I. mors-panacis and 2- the physiological and biochemical differences between the weakly and highly aggressive species as well as those between rusty and rotten ginseng plants. Eventually, we postulated that rusty symptom occurs on ginseng roots due to incompatible interactions with the weakly aggressive species of Ilyonectria, by the established iron-phenolic compound complexes while root-rot is developed by I. morspanacis infection due to the production of high quantities of hydrolytic and oxidative fungal enzymes which destroy the plant defensive barriers, in parallel with the pathogen growth stimulation by utilizing the available iron. Furthermore, we highlight future areas for study that will help elucidate the complete mechanism of root-rot disease development.

• 한국균학회지
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• 제45권2호
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• pp.132-138
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• 2017

작약에서 분리된 Cylindrocarpon destructans KACC44663 균주의 인삼에 대한 병원성 여부를 밝혀내고자 병원성 검정을 실시하였고 새로운 분류체계에 따른 균의 재분류를 위해 계통학적 유연관계를 분석하였다. 작약으로부터 분리된 KACC44663 균주가 인삼에 병을 일으키는 것을 확인하였고, 새로운 분류체계에 의해 I. radicicola species complex 내 위치하는 Ilyonectria robusta로 동정하였다. 이는 국내에서 타 기주로부터 분리된 병원균이 인삼에 뿌리썩음병을 일으키는 것을 증명한 첫 사례이다.

• Journal of Ginseng Research
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• 제43권1호
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• pp.1-9
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• 2019

Background: Korean ginseng is an important cash crop in Asian countries. However, plant yield is reduced by pathogens. Among the Ilyonectria radicicola-species complex, I. mors-panacis is responsible for root-rot and replant failure of ginseng in Asia. The development of new methods to reveal the existence of the pathogen before cultivation is started is essential. Therefore, a quantitative real-time polymerase chain reaction method was developed to detect and quantify the pathogen in ginseng soils. Methods: In this study, a species-specific histone H3 primer set was developed for the quantification of I. mors-panacis. The primer set was used on DNA from other microbes to evaluate its sensitivity and selectivity for I. mors-panacis DNA. Sterilized soil samples artificially infected with the pathogen at different concentrations were used to evaluate the ability of the primer set to detect the pathogen population in the soil DNA. Finally, the pathogen was quantified in many natural soil samples. Results: The designed primer set was found to be sensitive and selective for I. mors-panacis DNA. In artificially infected sterilized soil samples, using quantitative real-time polymerase chain reaction the estimated amount of template was positively correlated with the pathogen concentration in soil samples ($R^2=0.95$), disease severity index ($R^2=0.99$), and colony-forming units ($R^2=0.87$). In natural soils, the pathogen was recorded in most fields producing bad yields at a range of $5.82{\pm}2.35pg/g$ to $892.34{\pm}103.70pg/g$ of soil. Conclusion: According to these results, the proposed primer set is applicable for estimating soil quality before ginseng cultivation. This will contribute to disease management and crop protection in the future.