• Mycobiology
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• 제30권4호
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• pp.225-227
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• 2002

The inhibitory activity of ent-norsecurinine alkaloid was evaluated against spore germination of some plant pathogenic fungi(Curvularia maculans, Curvularia species, C. palliscens, Colletotrichum gloeosporioides, Colletotrichum species, Afternaria solani, A. brassicae, Fusarium udum, Helminthosporium echinoclova and H. penniseti). It inhibited spore germination of all the test fungi. C. maculans, C. species, and C. palliscens were the most sensitive as complete inhibition of spore germination was observed at 1000 ppm. A. solani was not inhibited by this chemical.

• Mycobiology
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• 제45권1호
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• pp.44-47
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• 2017

Ginseng damping-off, caused by the fungal pathogens Rhizoctonia solani and Pythium sp., is a critical disease in ginseng seedling. In a continuing effort to find microorganisms with the potential of acting as a biocontrol agent against Rhizoctonia damping-off, we found that a Streptomyces sp. A501 showed significant antifungal activity against Rhizoctonia solani. In field experiment to test the efficacy of Streptomyces sp. A501 in controlling ginseng damping-off, the incidence of damping-off disease was meaningfully reduced when ginseng seeds were soaked in the culture broth of Streptomyces sp. A501 before sowing. To perform characterization of the antifungal compound, we isolated it from the culture broth of strain A501 through Diaion HP-20 and silica gel column chromatographies and preparative high-performance liquid chromatography. The structure of the antifungal compound was assigned as fungichromin by spectroscopic methods, mainly nuclear magnetic resonance and electrospray ionization-mass analysis.

• 한국식물병리학회지
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• 제11권4호
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• pp.304-311
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• 1995

To determine whether chitinolytic enzymes from Chromobacterium violaceum C-61 play an important role in the suppression of Rhizoctonia damping-off, Tn5 insertion mutants deficient in chitinolytic activity (Chi a- mutants) were selected and their chitinolytic and disease suppression were compared with those of the parental strain. Four Chi a- mutants selected from about 2,000 transconjugants did not inhibit mycelial growth of Rhizoctonia solani on nutrient agar-potato dextrose agar (BA-PDA) and their abilities to suppress Rhizoctonia damping-off were much lower than the parental strain. However, population density in the eggplant rhizosphere did not differ significantly between the parental strain and four Chi a- mutants. The crude enzyme of the parental strain inhibited growth of R. solani on NA-PDA and its chitinase activity was much higher than that of Chi a- mutants. But the N,N' -diacetylchitobiase activity between these isolates were not significantly different. The chitinase of Chi a- mutants was defective in 2 isoforms of 52- and 37-kDa among four isoforms of 54-, 52-, 50- and 37-kDa. A Tn5 element was inserted into one site of 10 kb EcoRI fragment of chromosomal DNA in three Chi- mutants, C61-C1, -C2, and -C3. In C61-C4 mutant, a Tn5 element was inserted into two sites of 10 kb and 4.4 kb EcoRI fragments. These results suggest that the chitinase of C. violaceum C-61 play an important role in the suppression of Rhizoctonia damping-off of cucumber and eggplant.

• 한국균학회지
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• 제44권4호
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• pp.330-337
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• 2016

Streptomyces sp. A75와 A501 균주는 인삼 잘록병을 일으키는 R. solani와 Pythium sp.의 균사 생장을 억제하였다. 인삼 잘록병 R. solani에 대하여 Streptomyces sp. A75와 A501 균주의 배양액을 혼합한 50배 희석액에 종자 침지처리, 100배 희석액의 관주처리와 종자 침지처리(50배) + 관주처리(100배)는 81.3%, 84.8%와 32.2%의 방제 효과를 각각 나타내었다. 인삼 잘록병 Pythium sp.에 대하여 Streptomyces sp. A75와 A501 균주의 배양액을 혼합한 50배 희석액에 종자 침지처리, 100배 희석액의 관주처리와 종자 침지처리(50배) + 관주처리(100배)는 51.0%, 52.1%, 75.3%의 방제효과를 각각 나타내었다. 이들 결과에서 Streptomyces sp. A75와 A501 균주의 배양한 혼합액으로 종자 침지한 후 관주처리가 인삼 잘록병 발생을 효과적으로 감소시켰다.

• The Plant Pathology Journal
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• 제21권4호
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• pp.317-321
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• 2005

Since 2000 severe rots on aerial and underground parts of paprika (Capsicum annum L.) has occurred in most surveyed glasshouses throughout the country. A total of 56 isolates of a fungus were consistently isolated from various plant parts such as fruit, stem, branch, and root collected from 16 farms in five provinces. Anamorph stage of the fungus was identified as Fusarium solani based on its morphological characteristics. However, the fungus readily produced a sexual structure of perithecia on infected plant tissues and on agar media. Since the fungus formed abundant perithecium by a single isolate, it was considered as a homothallic strain of Nectria haematococca, the teleomorph of F. solani. Irregularly globose perithecia with orange to red color formed sparsely to gregariously on dead tissues of fruits and basal stems at the late infection stage, which is a diagnostic sign for the disease. Perithecia ranged from 125 to 220 ${\mu}m$ in diameter varied among isolates. Asci enveloping eight ascospores were cylindrical and measured 60-80x8-12 ${\mu}m$. Ellipsoid to obovate ascospores are two-celled and measured 11-18x4-7 ${\mu}m$. Ascospores were hyaline, slightly constricted at the central septum, and revealed longitudinal striations that is characteristic of the species. This fungus that has never been reported in Korea has previously become a threat to paprika cultivation because of its strong pathogenicity and nationwide distribution.

• 한국식물병리학회지
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• 제10권2호
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• pp.140-143
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• 1994

Comparison of susceptibility of asparagus (Asparagus officinalis L.) seedlings and plantlets to different fusarial species was made to determine whether in vitro propagated asparagus plantlets can be used as a substitute for seedlings in histopathological study on the infection processes of Fusarium species to asparagus. Fusarium oxysporum was isolated most frequently (50% of the total) from lesions of root and crown rot of asparagus cultivated in the field followed by F. moniliforme (8.8% of the total) and F. solani (2.9% of the total). Plantlets and seedlings of all asparagus were susceptible to f. moniliforme and F. oxysporum isolates, but those were not susceptible to both avirulent F. oxysporum (AVFO) and F. solani in pathogenicity tests. Overall, there were no differences between seedlings and plantlets in the susceptibility to virulent fusarial infections. In vitro propagated asparagus plantlets, therefore, could be used as a substitute for seedlings in histopathological study on the infection processes of Fuasrium species to asparagus.

• The Plant Pathology Journal
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• 제24권1호
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• pp.67-73
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• 2008

Seedling damping-off and bottom rot caused by Rhizoctonia solani are yield limiting diseases of crisphead lettuce. To provide biocontrol measure in the management of the diseases, biocontrol strain Pseudomonas aeruginosa LY-11 was isolated from lettuce rhizosphere and introduced into crisphead lettuce rhizosphere by the seed coating delivery method. Alginate was used as a coating material to generate beads containing $10^6-10^{6.5}$ colony-forming units (CFUs) of viable bacterial cells of LY-11. When seeds germinated from the alginate beads containing the strain LY-11, the bacteria established mostly in plant rhizosphere to maintain at least $10^4$ CFU per gram of plant tissues. Crisphead lettuce seedlings germinated from the entrapped seeds were less affected from damping-off and bottom rot with disease control values of 70.4% and 85.4% respectively. Although P. aeruginosa LY-11 colonized plant rhizosphere and not phyllosphere, the result indicated that bottom rot caused by the foliar inoculation of R. solani was effectively reduced by the rhizobacteria. All data suggested that immobilized rhizobacterial application in seeds by alginate coating could control damping-off and induce induced systemic resistance of crisphead lettuce to reduce bottom rot.

• Journal of Ginseng Research
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• 제44권1호
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• pp.161-167
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• 2020

Background: The ascomycete fungi Cylindrocarpon destructans (Cd) and Fusarium solani (Fs) cause ginseng root rot and significantly reduce the quality and yield of ginseng. Cd produces the secondary metabolite radicicol, which targets the molecular chaperone Hsp90. Fs is resistant to radicicol, whereas other fungal genera associated with ginseng disease are sensitive to it. Radicicol resistance mechanisms have not yet been elucidated. Methods: Transcriptome analyses of Fs and Cd mycelia treated with or without radicicol were conducted using RNA-seq. All of the differentially expressed genes (DEGs) were functionally annotated using the Fusarium graminearum transcript database. In addition, deletions of two transporter genes identified by RNA-seq were created to confirm their contributions to radicicol resistance. Results: Treatment with radicicol resulted in upregulation of chitin synthase and cell wall integrity genes in Fs and upregulation of nicotinamide adenine dinucleotide dehydrogenase and sugar transporter genes in Cd. Genes encoding an ATP-binding cassette transporter, an aflatoxin efflux pump, ammonium permease 1 (mep1), and nitrilase were differentially expressed in both Fs and Cd. Among these four genes, only the ABC transporter was upregulated in both Fs and Cd. The aflatoxin efflux pump and mep1 were upregulated in Cd, but downregulated in Fs, whereas nitrilase was downregulated in both Fs and Cd. Conclusion: The transcriptome analyses suggested radicicol resistance pathways, and deletions of the transporter genes indicated that they contribute to radicicol resistance.

• 한국응용곤충학회지
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• 제60권4호
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• pp.339-355
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• 2021

진딧물은 직접적으로 식물의 체관부를 흡즙함으로써 식물 피해를 줄 뿐 아니라 식물 바이러스를 매개하고 그을음병을 유발시켜 식물에 이차적인 피해를 준다. 식량작물에 영향을 주는 기장테두리진딧물(Rhopalosiphum padi), 싸리수염진딧물(Aulacorthum solani), 아카시아진딧물(Aphis craccivora), 완두수염진딧물(Acyrthosiphon pisum)의 발육, 생존, 번식에 미치는 온도의 영향을 생명표분석을 통하여 비교하였다. 10, 15, 20, 25, 30℃에서 얻은 발육단계별 발육기간, 생존율, 성충수명, 성충산자 자료를 암수이용생명표분석(age-stage, two-sex life table analysis) 방법을 이용하여 생명표매개변수를 추정하였다. 싸리수염진딧물은 30도에서 성충으로 발육하지 못하였다. 15℃를 제외한 모든 온도에서 기장 테두리진딧물의 내적자연증가율이 가장 높았으며 (10, 20, 25, 30℃에서 0.12, 0.34, 0.47, 0.32) 30도에서 완두수염진딧물의 내적자연증가율은 음의 값 (-0.04)이었다. 식량작물을 가해하는 진딧물 4종의 생명표 매개변수 비교분석을 통해 저온 적응성이 높은 종은 싸리수염진딧물이었고 고온 환경에서는 기장테두리진딧물이 우점할 것으로 추정되었다.

• 한국작물학회지
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• 제44권4호
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• pp.373-381
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• 1999

Six soybean cultivars having different SDS susceptibility were planted with sorghum seedinoculum infested with F. solani isolate 171 in the greenhouse. First leaf symptoms appeared on unifoliar leaves at 9 days after inoculation and all cultivars showed the typical leaf symptoms at 13 days after inoculation, when trifoliar leaves emerged. Leaf symptoms development in susceptible cultivars was faster than in resistant cultivars. Leaf symptom severities during the period of 25 to 29 days after inoculation showed a significant difference between cultivars which had SDS resistance and sus ceptibility. In this period, area under the diseaseprogress curve (AUDPC) of Hartz 6686 was the highest and that of PI 520733 was the lowest. SDS caused serious damage to the growth of soybean in all cultivars. Average reductions of growth rate of root fresh weight and dry weight were greater than those of plant tops. Duyu-kong showed less severe leaf symptoms than that of SDS suscetible cultivars; however, average growth rate of plants top and roots of this cultivar was less but not significantly different than those of SDS susceptible cultivars. In all cultivars, as severity of leaf symptoms increased, plant top weight decreased. Root rot symptoms were observed in all cultivars before leaf symptoms appeared. Average proportions of tap root reddish-brown discoloration of all cultivars was up to 75 % at 15 days after inoculati on; however there was no significant differenc between cultivars at each rating date. Appearances of leaf symptoms on leaves varied in each cultivar. SDS resistant cultivars had a significantly higher level of crinkling than susceptible cultivars and SDS susceptible cultivars had a significantly higher level of necrosis than resistant cultivars. Further study will be needed to identify the relationships between the physiological growth rate and SDS severities in soybeans.