• The Plant Pathology Journal
• /
• 제32권3호
• /
• pp.182-189
• /
• 2016

Together with the Fusarium graminearum species complex, F. culmorum is a major member of the causal agents of Fusarium head blight on cereals such as wheat, barley and corn. It causes significant yield and quality losses and results in the contamination of grain with mycotoxins that are harmful to humans and animals. In Korea, F. culmorum is listed as a quarantine fungal species since it has yet to be found in the country. In this paper, we report that two isolates (J1 and J2) of F. culmorum were collected from the air at a rice paddy field in Korea. Species identification was confirmed by phylogenetic analysis using multilocus sequence data derived from five genes encoding translation elongation factor, histone H3, phosphate permease, a reductase, and an ammonia ligase and by morphological comparison with reference strains. Both diagnostic PCR and chemical analysis confirmed that these F. culmorum isolates had the capacity to produce nivalenol, the trichothecene mycotoxin, in rice substrate. In addition, both isolates were pathogenic on wheat heads and corn stalks. This is the first report on the occurrence of F. culmorum in Korea.

• The Plant Pathology Journal
• /
• 제30권1호
• /
• pp.33-42
• /
• 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.

• 한국식물병리학회지
• /
• 제14권5호
• /
• pp.418-424
• /
• 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.

• Asian-Australasian Journal of Animal Sciences
• /
• 제31권12호
• /
• pp.1903-1912
• /
• 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.

• 한국식품위생안전성학회지
• /
• 제37권1호
• /
• pp.9-14
• /
• 2022

본 연구에서는 가래떡에 오염된 곰팡이를 분리 동정한 후 곰팡이독소 생산 가능성을 조사하여 식품 이물 중 곰팡이에 대한 위험성을 분석하였다. 실험에 사용된 가래떡은 전라남도 소재 떡 제조업체에 곰팡이로 추정되는 이물이 발견되어 반품된 제품을 사용하였다. 곰팡이 이물을 채취한 후 Potato dextrose agar, Malt extract agar, Czapek yeast extract agar에 접종하고 25℃에서 7일간 배양하여 순수 분리 결과를 판단하였다. 순수 분리가 확인된 집락에 대해 광학현미경으로 포자의 미세구조를 관찰하여 형태학적으로 동정하였다. 유전학적 동정은 ITS primer를 이용하여 증폭된 PCR 산물의 유전자 염기서열을 분석하였다. Colony-1과 2는 각각 배지에서 동일한 성상을 나타내어 순수분리 되었음을 확인하였다. Colony-1은 출아세포가 관찰되어 효모로 판정하였다. Colony-2는 방추형의 분생자가 관찰되어 Fusarium 속 곰팡이로 판정하였다. 유전자 염기서열 분석 결과 Fusarium 속 곰팡이가 총 76건으로 나타났으며, 그중 Fusarium solani가 53건으로 가장 높게 나타났다. 형태학적 동정 결과와 유전학적 동정 결과를 바탕으로 Colony-2는 Fusarium spp.로 동정되었고 그 중 Fusarium solani로 추정되었다. Fusarium 속 곰팡이는 Nivalenol, Zearalenone, Fumonisin 등의 곰팡이독소를 생산하여 구토, 설사, 암 등을 유발한다. 이러한 결과를 종합해 볼 때 가래떡에서 분리된 Fusarium 속 곰팡이에 의한 곰팡이독소 생산 가능성은 상존하는 것으로 판단되었다. 따라서 곰팡이 이물이 보고되면 곰팡이를 분리 동정하여 곰팡이독소를 생산할 수 있는 균종인지 판단하고, 그 결과에 따라 행정조치를 강화하여야 할 것으로 판단된다.

• The Plant Pathology Journal
• /
• 제38권6호
• /
• pp.637-645
• /
• 2022

Fusarium head blight (FHB) is one of the most serious diseases in barley and wheat, as it is usually accompanied by the production of harmful mycotoxins in the grains. To identify FHB-resistant breeding resources, we evaluated 60 elite germplasm accessions of barley (24) and wheat (36) for FHB and mycotoxin accumulation. Assessments were performed in a greenhouse and five heads per accession were inoculated with both Fusarium asiaticum (Fa73, nivalenol producer) and F. graminearum (Fg39, deoxynivalenol producer) strains. While the accessions varied in disease severity and mycotoxin production, four wheat and one barley showed <20% FHB severity repeatedly by both strains. Mycotoxin levels in these accessions ranged up to 3.9 mg/kg. FHB severity was generally higher in barley than in wheat, and Fa73 was more aggressive in both crops than Fg39. Fg39 itself, however, was more aggressive toward wheat and produced more mycotoxin in wheat than in barley. FHB severity by Fa73 and Fg39 were moderately correlated in both crops (r = 0.57/0.60 in barley and 0.42/0.58 in wheat). FHB severity and toxin production were also correlated in both crops, with a stronger correlation for Fa73 (r = 0.42/0.82 in barley, 0.70 in wheat) than for Fg39.

• 미생물학회지
• /
• 제31권4호
• /
• pp.312-317
• /
• 1993

강원도와 남부지방에서 각각 옥수수와 보리를 채집하여 두 곡류로 부터 총 110 균주의 Fusatium graminearum을 분리한 후 쌀배지에서의 trichothecene과 zearalenone(ZEA)의 생성능을 측정하였다. 옥수수로 부터 분리한 51개의 F. graminearum 균주중 trichothecene 생성빈도는 deoxynivalenol(Don)이 64.5%, 3-acetyldeoxynivalenol (3-ADON)이 7.8%, 15acetyldeoxynivalenol (15-ADON)이 33.3%, nivalenol(NIV)이 21.6%, 4-acetylnivalenol (4-ANIV)이 13.7%였다. DON을 생성하는 균주들은 3-ADON보다는 15-ADON을 동시에 생성하였다. 한편, 보리로부터 분리한 59개의 F. graminearum 균주중 trichothecene 생성빈도는 NIV가 71.2%, 그리고 4-ANIV가 61.0%였으며, 한 균주만이 DON과 3-ADON을 동시에 생성하였다. 옥수수로부터 분리한 균주들의 ZEA의 생성빈도와 생성량은 각각 32.0%, 71㎍/g였으며, 보리로부터 분리한 균주는 각각 29%, 745㎍이었다. 이와같이 우리나라 강원도지방과 남부지방의 F. graminearum 균주들의 trichothecene 생성양상은 지역적인 큰 차이를 나타내었다.

• 한국균학회소식:학술대회논문집
• /
• 한국균학회 2016년도 춘계학술대회 및 임시총회
• /
• pp.33-33
• /
• 2016

Mycotoxins are toxic secondary metabolites produced by fungi. They can be present in where agricultural-based commodities are contaminated with toxigenic fungi. These mycotoxins cause various toxicoses in human and livestock when consumed. Small grains including corn, barley, rice or wheat are frequently contaminated with mycotoxins due to infection mainly by toxigenic Fusarium species and/or under environment favorable to fungal growth. One of the most well-known Fusarium toxin groups in cereals is trichothecenes consisting of many toxic compounds. Deoxynivalenol (DON), nivalenol (NIV), T-2 toxin, and various derivatives belong to this group. Zearalenone and fumonisin (FB) are also frequently produced by many species of the same genus. In order to monitor Korean cereals for contamination with Fusarium and other mycotoxigenic fungal species as well, barley, corn, maize, rice grains, and soybean were collected from fields at harvest or during storage for several years. The fungal colonies outgrown from the grain samples were identified based on morphological and molecular characteristics. Trichothecene chemotypes of Fusarium species or presence of FB biosynthetic gene were determined using respective diagnostic PCR to predict possible toxin production. Heavy grain contamination with fungi was detected in barley, rice and wheat. Predominant fungal genus of barley and wheat was Alternaria (up to 90%) while that of rice was Fusarium (~40%). Epicoccum also appeared frequently in barley, rice and wheat. While frequency of Fusarium species in barley and wheat was less than 20%, the genus mainly consisted of Fusarium graminearum species complex (FGSC) which known to be head blight pathogen and mycotoxin producer. Fusarium composition of rice was more diverse as FGSC, Fusarium incarnatum-equiseti species complex (FIESC), and Fusarium fujikuroi species complex (FFSC) appeared all at considerable frequencies. Prevalent fungal species of corn was FFSC (~50%), followed by FGSC (<30%). Most of FFSC isolates of corn tested appeared to be FB producer. In corn, Fusarium graminearum and DON chemotype dominate within FGSC, which was different from other cereals. Soybeans were contaminated with fungi less than other crops and Cercospora, Cladosporium, Alternaria, Fusarium etc. were detected at low frequencies (up to 14%). Other toxigenic species such as Aspergillus and Penicillium were irregularly detected at very low frequencies. Multi-year survey of small grains revealed dominant fungal species of Korea (barley, rice and wheat) is Fusarium asiaticum having NIV chemotype.