• The Plant Pathology Journal
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• v.38 no.3
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• pp.212-219
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• 2022

Fusarium root rot caused by the soil-borne fungus Fusarium solani is one of the most important fungal diseases of cassava in Thailand, resulting in high yield losses of more than 80%. This study aimed to investigate if the exogenous application of salicylic acid formulations (Zacha) can induce resistance in cassava against Fusarium root rot and observe the biochemical changes in induced cassava leaf tissues through synchrotron radiation based on Fourier-transform infrared (SR-FTIR) microspectroscopy. We demonstrated that the application of Zacha11 prototype formulations could induce resistance against Fusarium root rot in cassava. The in vitro experimental results showed that Zacha11 prototype formulations inhibited the growth of F. solani at approximately 34.83%. Furthermore, a significant reduction in the disease severity of Fusarium root rot disease at 60 days after challenge inoculation was observed in cassava plants treated with Zacha11 at a concentration of 500 ppm (9.0%). Population densities of F. solani were determined at 7 days after inoculation. Treatment of the Zacha11 at a concentration of 500 ppm resulted in reduced populations compared with the distilled water control and differences among treatment means at each assay date. Moreover, the SR-FTIR spectral changes of Zacha11-treated epidermal tissues of leaves had higher integral areas of lipids, lignins, and pectins (1,770-1,700/cm), amide I (1,700-1,600/cm), amide II (1,600-1,500/cm), hemicellulose, lignin (1,300-1,200/cm), and cellulose (1,155/cm). Therefore, alteration in defensive carbohydrates, lipids, and proteins contributed to generate barriers against Fusarium invasion in cassava roots, leading to lower the root rot disease severity.

• Mycobiology
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• v.31 no.2
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• pp.95-98
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• 2003

Aantifungal agents were tested against 30 clinical isolates of Cryptococcus neoformans var. neoformans using the NCCLS method(M27-A2). Posaconazole, itraconazole and amphotericin B had lower MIC than the remaining four antifungal agents. The MIC result for posaconazole was over 220-fold lower active than fluconazole. Fluconazole MICs for most isolates fell within the dose-dependant range. The overall MIC ranges and $MIC_{50}s$ were amphotericin B(0.03-0.25; 0.25), fluconazole(0.5-64; 16), itraconazole(0.015-1; 0.125), terbinafine(0.06->2; 1), caspofungin(8-32; 32), voriconazole(0.015-0.5; 0.25), and posaconazole(0.015-0.25; 0.06 ${\mu}g/ml$), respectively. In conclusion, the $MIC_{50}s$ of these drugs did not exhibit any sign of an upward shift with the exception of fluconazole and tendency cross-resistance between the seven drugs was not observed. We conclude that in vitro resistance to antifungal agents has not significantly changed despite the recent wide-spread use of triazoles for long-term treatment of Cryptococcal meningitis.

• Korean Journal Plant Pathology
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• v.13 no.2
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• pp.79-84
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• 1997

Incidence of rice blast on new rice cultivars and elite lines was observed from 194 to 1996 in Icheon, Chuncheon, Jecheon and Naju areas. The observations were made in the nuseries and in the fields. In the nurseries, only cultivars Daesanbyeo and Hyangmibyeo 2 showed moderate levels of resistance to leaf blast, with the disease index 0 to 6. From the field observations, it was found that cultivars Hyangmibyeo 2 and Suwon 414 were highly resistant to leaf blast, but susceptible to neck blast. the fields, leaf blast was not observed. In general, there was great yearly and regional variation in the incidence of neck blast within the same cultivars, some times ranging from 0 to 100% of incidence. However, the range of fluctuation in the disease incidence were relatively small in the cultivars Daejinbyeo (0∼17.5%), Daesanbyeo (0∼4.0%), Donganbyeo (0∼21.4%) and Hwasambyeo (0∼13.9%). Hyangmibyeo 2 and Seojinbyeo were rarely infected with neck blast in Chuncheon and Naju all of the years, the same cultivars were severely infested with neck blast; 45.1 and 45.5%, respectively, in Jecheon in 1995. The occurrence of different races of rice blast fungus were different at different areas. However, it was found that in Icheon, Chuncheon, Jecheon and Naju areas, the dominant races were KI-409, KJ-201 and KJ-301.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.110-115
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• 2013

Theobroxide, a novel compound isolated from a fungus Lasiodiplodia theobromae, stimulates potato tuber formation and induces flowering of morning glory by initiating the jasmonic acid synthesis pathway. To elucidate the effect of theobroxide on pathogen resistance in plants, Nicotiana benthamiana plants treated with theobroxide were immediately infiltrated with Pseudomonas syringae pv. tabaci. Exogenous application of theobroxide inhibited development of lesion symptoms, and growth of the bacterial cells was significantly retarded. Semiquantitative RT-PCRs using the primers of 18 defense-related genes were performed to investigate the molecular mechanisms of resistance. Among the genes, the theobroxide treatment increased the expression of patho-genesis-related protein 1a (PR1a), pathogenesis-related protein 1b (PR1b), glutathione S-transferase (GST), allen oxide cyclase (AOC), and lipoxyganase (LOX). All these data strongly indicate that theobroxide treatment inhibits disease development by faster induction of defense responses, which can be possible by the induction of defense-related genes including PR1a, PR1b, and GST triggered by the elevated jasmonic acid.

• Research in Plant Disease
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• v.16 no.2
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• pp.141-147
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• 2010

Resistance to Phytophthora blight (Phytophthora capsici Leonian) of commercial cultivars of Capsicum pepper in Korea were evaluated from 2008 to 2010. In 2008 and 2009, the cultivars were tested for resistance to the Pc003 isolate collected in Youngyang, Gyeongbuk province. In 2010, the selected cultivars in the previous years were tested by inoculating with 3 isolates obtained from the pepper plants in Miryang in Gyeongnam province, Youngyang in Gyeongbuk province, and Goesan in Chungbuk province. A continuous variation in resistance from highly resistant to susceptible was observed among the commercial pepper cultivars. It was also noted that some cultivars, although their names were initiating with 'Yeokgang' or 'PR' meaning Phytophthora resistance, were very low in resistance or susceptible. When the resistant cultivars selected in 2008 and 2009 experiment were inoculated with the 3 isolates, all the commercial cultivars except a rootstock, 'Tantan', succumbed to the exceptionally virulent Pc005 (Miryang) isolate. Pc002 (Goesan) was a little more virulent than Pc003 (Youngyang). A few cultivars resistant to Pc003 (Youngyang) were severely infected by Pc002 (Goesan). Significant interaction in analysis of variance suggested the differential interactions between cultivars and pathogen isolates. Strategies to breed cultivars having high level of resistance to the highly variable pathogenic fungus, Phytophthora capsici, were discussed.

• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.338-343
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• 1995

Incidence of blast caused by Pyricularia grisea on five new cultivars and four elite lines (C/L) of rice was investigated at different locations, Icheon, Chuncheon, Jecheon and Naju, 1992 to 1994. Disease indices of leaf blast on the tested C/L except Juanbyeo and Keumnambyeo ranged from 0 to 6 in the blast nursery. Under the field conditions, percentages of diseased leaf area of Kuemnambyeo were 6.5% in Jecheon and 2.8% in Icheon in 1993. The incidence of panicle blast on the C/L except Suweon 394 and Milyang 117 differed depending on the locations and years. In case of Unjangbyeo, panicle blast was rarely observed n the fields in Icheon and Naju, but the disease incidences were 21.8% in Jecheon in 1993 and 16.4% in Chuncheon in 1994. Race distribution of the blast fungus was variable according to the locations. The major race in the Jecheon site was KI-197, which was recently identified.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.78-82
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• 1994

Unusually severe rice blast epidemic sweeped over the rice growing area in Gyeongnam Province and elsewhere in 1993. Leaf blast infection was reached to 33,133 ha, which is about 24.5% of total paddy area and neck blast infection was apparent throughout 4,421 ha. Major factors affecting such an unusual epidemic appeared to be as follow: Firstly, low temperature, frequent rainfall and coincidentally insufficient duration of sunshine through July and August; Secondly, most cultivars possessing low levels of field resistance were cultivated in wide areas: Thirdly, blast fungus population was enough for successive infection under optimum weather condition and most races distributed in field were able to infect most cultivars.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.123-128
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• 1994

Incidence of blast caused by Pyricularia grisea Sacc. on 21 leading cultivars and elite lines of rice was investigated in different locations such as Icheon, Chuncheon, Jecheon, and Naju during three years from 1991 to 1993. Disease index of leaf blast of Dongjinbyeo was high in the blast nursery with range 4 to 9 at Naju, but low at other locations with range 1 to 4. Percentages of diseased leaf area of Joryungbyeo and Daelipbyeo 1 were 4.3 and 12%, respectively in the fields at Jecheon in 1993, but were much lower in the other locations during three years. The incidences of leaf blast of Daelipbyeo 1 were 0.3 and 12.0% at Chuncheon and Jecheon, respectively in 1993, but no disease occurred at Naju during three years. Percentage of diseased panicles of Joryungbyeo was 100% at Icheon and Jecheon in 1993, 92.4% in Suweon 390 at Icheon on 1991 and 100% in Jinbu 15 at Jecheon on 1993. Race distribution of rice blast fungus at Icheon and Jecheon was more varied than that of the other locations.

• Research in Plant Disease
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• v.21 no.3
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• pp.227-230
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• 2015

The ascomycete fungus Fusarium fujikuroi causes bakanae disease in rice and this disease has been reemerging in Korea. Other fungal species including F. graminearum and Magnaporthe oryzae are often associated with F. fujikuroi, hampering pure isolation of F. fujikuroi from rice. In this study, we modified a selective medium for F. fujikuroi as supplementing both pentachloronitrobenzene and hydrogen peroxide into minimal medium. This medium efficiently suppressed the vegetative growth of F. graminearum and M. oryzae, but did not significantly reduce F. fujikuroi growth, providing an efficient tool for isolating F. fujikuroi.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.23-23
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• 2015

Rice blast disease caused by M. oryzae is the most devastating fungal disease in rice. During the infection process, M. oryzae secretes a large number of glycosyl hydrolase (GH) proteins into the apoplast to digest host cell wall and assist fungal ingress into host tissues. In this study, we identified a novel M. oryze arabinofuranosidase B (MoAbfB) which is secreted during fungal infection. Live-cell imaging exhibited that fluorescent labeled MoAbfB was highly accumulated in fungal invasive structures such as appressorium, tips of penetration peg, biotrophic interfacial complex (BIC), as well as invasive hyphal tip. Deletion of MoAbfB mutants extended biotrophic phase followed by enhanced disease severity, whereas, over-expression of OsMoAbfB mutant induced rapid defense responses and enhanced rice resistance to M. oryzae infection. Furthermore, exogenous treatment of MoAbfB protein showed inhibition of fungal infection via priming of defense gene expression. We later found that the extract of MoAbfB degraded rice cell wall fragments could also induce host defense activation, suggesting that not MoAbfB itself but oligosaccharides (OGs) derived from MoAbfB dissolved rice cell wall elicited rice innate immunity.