• The Plant Pathology Journal
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• v.34 no.5
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• pp.347-355
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• 2018

Fusarium head blight (FHB) caused by Fusarium species is a major disease of wheat and barley around the world. FHB causes yield reductions and contamination of grains with trichothecene mycotoxins including; nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), and 15-acetyldeoxynivalenol (15-ADON). The objectives of this study were to identify strains of F. graminearum isolated in Korea from 2012-harvested wheat grain and to test the pathogenicity of these NIV- and DON-producing isolates. Three hundred and four samples of wheat grain, harvested in 2012 in Chungnam, Chungbuk, Gyeongnam, Jeonbuk, Jeonnam, and Gangwon provinces were collected. We recovered 44 isolates from the 304 samples, based on the PCR amplification of internal transcribed spacer (ITS) rRNA region and sequencing. Our findings indicate that F. asiaticum was the predominant (95% of all isolates) species in Korea. We recovered both F. asiaticum and F. graminearum from samples collected in Chungnam province. Of the 44 isolates recovered, 36 isolates had a NIV genotype while 8 isolates belonged to the DON genotype (3-ADON and 15-ADON). In order to characterize the pathogenicity of the strains collected, disease severity was assessed visually on various greenhouse-grown wheat cultivars inoculated using both NIV- and DON-producing isolates. Our results suggest that Korean F. graminearum isolates from wheat belong to F. asiaticum producing NIV, and both F. graminearum and F. asiaticum are not significantly different on virulence in wheat cultivars.

• The Plant Pathology Journal
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• v.35 no.6
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• pp.543-552
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• 2019

Fusarium asiaticum of the F. graminearum species complex causes head blight in small-grain cereals. The nivalenol (NIV) chemotypes of F. asiaticum is more common than the deoxynivalenol (DON) chemotypes of F. asiaticum or F. graminearum in Korea. To understand the prevalence of F. asiaticum-NIV in Korean cereals, we characterized the biological traits of 80 cereal isolates of F. asiaticum producing NIV or 3-acetyl-deoxynivalenol (3-ADON), and 54 F. graminearum with 3-ADON or 15-acetyl-deoxynivalenol (15-ADON). There was no significant difference in mycelial growth between the chemotypes, but F. asiaticum isolates grew approximately 30% faster than F. graminearum isolates on potato dextrose agar. Sexual and asexual reproduction capacities differed markedly between the two species. Both chemotypes of F. graminearum (3-ADON and 15-ADON) produced significantly higher numbers of perithecia and conidia than F. asiaticum-NIV. The highest level of mycotoxins (sum of trichothecenes and zearalenone) was produced by F. graminearum-3-ADON on rice medium, followed by F. graminearum-15-ADON, F. asiaticum-3-ADON, and F. asiaticum-NIV. Zearalenone levels were correlated with DON levels in some chemotypes, but not with NIV levels. Disease assessment on barley, maize, rice, and wheat revealed that both F. asiaticum and F. graminearum isolates were virulent toward all crops tested. However, there is a tendency that virulence levels of F. asiaticum-NIV isolates on rice were higher than those of F. graminearum isolates. Taken together, the phenotypic traits found among the Korean F. asiaticum-NIV isolates suggest an association with their host adaptation to certain environments in Korea.

• The Plant Pathology Journal
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• v.30 no.1
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• pp.33-42
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• 2014

Nivalenol (NIV) and deoxynivalenol (DON) are predominant Fusarium-producing mycotoxins found in grains, which are mainly produced by Fusarium asiaticum and F. graminearum. NIV is found in most of cereals grown in Korea, but the genetic basis for NIV production by F. asiaticum has not been extensively explored. In this study, 12 genes belonging to the trichothecene biosynthetic gene cluster were compared at the transcriptional level between two NIV-producing F. asiaticum and four DON-producing F. graminearum strains. Chemical analysis revealed that time-course toxin production patterns over 14 days did not differ between NIV and DON strains, excluding F. asiaticum R308, which was a low NIV producer. Both quantitative real-time polymerase chain reaction and Northern analysis revealed that the majority of TRI gene transcripts peaked at day 2 in both NIV and DON producers, which is 2 days earlier than trichothecene accumulation in liquid medium. Comparison of the gene expression profiles identified an NIV-specific pattern in two transcription factor-encoding TRI genes (TRI6 and TRI10) and TRI101, which showed two gene expression peaks during both the early and late incubation periods. In addition, the amount of trichothecenes produced by both DON and NIV producers were correlated with the expression levels of TRI genes, regardless of the trichothecene chemotypes. Therefore, the reduced production of NIV by R308 compared to NIV or DON by the other strains may be attributable to the significantly lower expression levels of the TRI genes, which showed early expression patterns.

• Applied Biological Chemistry
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• v.37 no.5
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• pp.385-391
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• 1994

The occurrence of Fusarium mycotoxins was surveyed in 68 corn samples imported from China. Four 8-ketotrichothecenes including deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON), 3-acetyldeoxynivalenol (3-ADON), and nivalenol (NIV) were detected in corn. In addition, the corn samples were contaminated with zearalenone (ZEA), fumonisin $B_1$, $(FB_1)$, fumonisin $B_2$, and fumonisin $B_3$. DON, 15-ADON, 3-ADON, ZEA, and $FB_1$ were major contaminants in corn, with mean levels of 277, 34, 37, 39, and 123 ng/g, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.12
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• pp.1903-1912
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• 2018

Objective: To evaluate the effect of lactic acid bacteria and storage temperature on the microbial, chemical and mycotoxin composition of corn silage. Methods: Corn was harvested at 32.8% dry matter, and chopped to 1 to 2 cm. The chopped material was subjected to three treatments: i) control (distilled water); ii) $1{\times}10^6$ colony forming units (cfu)/g of Lactobacillus plantarum; iii) $1{\times}10^6cfu/g$ of Pediococcus pentosaceus. Treatments in triplicate were ensiled for 55 d at $20^{\circ}C$, $28^{\circ}C$, and $37^{\circ}C$ in 1-L polythene jars following packing to a density of approximately $800kg/m^3$ of fresh matter, respectively. At silo opening, microbial populations, fermentation characteristics, nutritive value and mycotoxins of corn silage were determined. Results: L. plantarum significantly increased yeast number, water soluble carbohydrates, nitrate and deoxynivalenol content, and significantly decreased the ammonia N value in corn silage compared with the control (p<0.05). P. pentosaceus significantly increased lactic acid bacteria and yeast number and content of deoxynivalenol, nivalenol, T-2 toxin and zearalenone, while decreasing mold population and content of nitrate and 3-acetyl-deoxynivalneol in corn silage when stored at $20^{\circ}C$ compared to the control (p<0.05). Storage temperature had a significant effect on deoxynivalenol, nivalenol, ochratoxin A, and zearalenone level in corn silage (p<0.05). Conclusion: Lactobacillus plantarum and Pediococcus pentosaceus did not decrease the contents of mycotoxins or nitrate in corn silage stored at three temperatures.

• Research in Plant Disease
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• v.25 no.4
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• pp.157-163
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• 2019

This study aimed to assess the incidence and distribution of toxigenic fungi in Korean oat. Toxigenic fungi were isolated from oat samples collected from 12 oat fields from heading to harvest in 2017 and 2018. A total of 745 fungal colonies were isolated based on morphology and identified using marker genes. About 92% of the fungal isolates were Fusarium spp. and others were Penicillium (5.9%) and Aspergillus (2.1%). Fusarium isolates comprised mostly of F. asiaticum (83.1%), followed by F. incarnatum (5.4%), F. proliferatum (3.5%), F. fujikuroi (2.8%), F. tricinctum species complex (FTSC) 11 (1.5%) and F. graminearum (1.0%). About 97% of F. asiaticum was nivalenol type, and 3-acetyl deoxynivalenol (3.2%) and 15-acetyl deoxynivalenol (0.4%) types also were found. Pathogenicity test of the selected Fusarium isolates revealed that F. asiaticum isolates have a wide range of virulence depending on the tested plants. F. graminearum and FTSC 11 isolates from blighted spikelets were the most virulent in naked oat. All Fusarium isolates (n=18) except one (FTSC 11) produced nivalenol (0.2-7.6 ㎍/g), deoxynivalenol (0.03-6.1 ㎍/g), and zearalenone (0.1-27.0 ㎍/g) on rice medium. This study is first report that F. asiaticum causes Fusarium head blight disease of oat in Korea. These findings demonstrate the dominance of F. asiaticum in oat agroecosystems as in rice, wheat and barley in Korea.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.418-424
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• 1998

The production of 8-ketotrichothecenes, deoxynivalenol (DON), nivalenol (NIV), and their monoacetyl derivatives was studied in rice and corn cultures using 8 isolates of Fusarium graminearum which were obtained from corn and barley samples. Higher concentrations of trichothecenes were produced on rice than corn, and production of the toxins on rice was enhanced by growing the fungi at $25^{\circ}C$. The isolates were used for evaluation of toxin production and pathogenicity after artificial inoculation to 5 corn and 3 barley cultivars. The kinds and the relative amounts of trichothecenes produced in cultures were consistent with those in infected kernels of corn and barley with some exceptions. As for DON chemotypes, the ratios of 15-acetyl-DON to 3-acetyl-DON were varied among the pathogen-cultivar interactions. The corn and barley cultivars showed the significant differences of resistance to the Fusarium isolates in disease severity and seedling blight, and resistance ranking to the different isolates was varied. However, significant correlations were observed between the total concentrations of trichothecenes in infected kernels of corn and barley and pathogenicities of the Fusarium isolates to the hosts.

• Research in Plant Disease
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• v.25 no.4
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• pp.213-219
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• 2019

A total of 1,159 Fusarium strains were isolated from sorghum grown in Danyang and Youngwol in 2017 and 2018. The isolates were analyzed to reveal genetic, toxigenic and pathogenic characteristics. Phylogenetic analysis using TEF-1α and RPB2 genes showed that the samples were contaminated with at least 17 Fusarium species. Among them, F. graminearum, F. proliferatum, F. thapsinum, F. incarnatum, and F. asiaticum were dominant species. In F. graminearum and F. asiaticum, F. graminearum-15-acetyl deoxynivalenol chemotype and F. asiaticum-nivalenol chemotype were frequent. Six Fusarium species tested produced one or more mycotoxins, except F. thapsinum and FTSC 11. F. proliferatum and F. fujikuroi had FUM1 gene (76.0% and 81.6%, respectively) and some isolates produced high level of fumonisin (over 1,000 ㎍). F. proliferatum and F. thapsinum were more virulent than other species on sorghum. These results indicate that Fusarium species in sorghum might produce multiple mycotoxins.

• Analytical Science and Technology
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• v.11 no.3
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• pp.206-212
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• 1998

The major mycotoxins were detected from peppers, onions and garlics infected postharvest pathogens, Alternaria, Penicillium and Fusarium. Analyses of the major mycotoxins were conducted using HPLC. Detected Alternaria mycotoxins per gram of infected postharvest peppers were alternariol (AOH) with amount ranged from small quantity to $440{\mu}g/g$, altenuene (ALT) with amount ranged from small quantity to $103{\mu}g/g$, tenuagonic acid (TeA) with amount ranged from 249 to $342{\mu}g/g$ and alternariol monomethyl ether (AME) with amount ranged from 206 to $294{\mu}g/g$. Penicillium toxins per gram of infected postharvest onions and garlics were citrinin with amount ranged from 2.8 to $18.4{\mu}g/g$, penicillun-G with amount ranged from no detection to $439.0{\mu}g/g$, penicillic acid with amount ranged from no detection to small quantity and patulin with amount ranged from no detection to small quantity. Fusarium toxins per gram of infected postharvest onions and garlics were fusaric acid with amount ranged from no detection to $553.6{\mu}g/g$. However, deoxyrivalenol and nivalenol were not detected from onins and garlics infected by Fusarium.

• Research in Plant Disease
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• v.24 no.4
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• pp.308-312
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• 2018

We analyzed rice sample with scab (collected in 2017) for fungal occurrence and found that frequency of Fusarium spp. was the highest among fungal genera. Within Fusarium, Fusarium asiaticum-nivalenol type dominated as 79%. Among mycotoxins, zearalenone was the highest toxin detected (1117 ng/g), followed by deoxynivalenol (163 ng/g), 15-acetyl deoxynivalenol (155 ng/g), nivalenol (110 ng/g). Analysis of mycotoxin levels in scabby and healthy grains (collected in 2015) revealed that both grain samples were contaminated with zearalenone. However, level difference of zearalenone between the samples was over 5 times as the scabby samples were 1400-2370 ng/g, while healthy ones were 240-430 ng/g. This result indicates that scabby grains should be removed when harvest to reduce zearalenone contamination in rice.