Effects of Temperature and Humidity on Fungal Occurrence in Dried Red Pepper during Storage

Sosoo Kim,Seul Gi Baek,Nguyen Bao Hung,Se-Ri Kim,Ja Yeong Jang,Jeomsoon Kim,Theresa Lee 한국식물병리학회 2021 식물병연구 Vol.27 No.4

Dried red peppers are frequently contaminated with mycotoxins during storage. To determine the effect of storage environments on fungal occurrence and subsequent mycotoxin accumulation in dried red peppers, we monitored red pepper powder and whole fruit samples for fungal occurrence under various tempera- tures and relative humidity (RH) conditions during 340 days. Fungal occurrences fluctuated in both pepper forms throughout the storage but they were higher in pepper powder than whole one, higher under low temperatures (-20°C, 0°C, or 4°C) than others (10°C, 25°C, or 30°C), and higher under RH 93% than RH 51% and 69% in both peppers. The samples exhibiting high fungal occurrences were associated mainly with dom- inant species such as Aspergillus sydowii, Penicillium solitum, P. roqueforti, P. polonicum, or P. chrysogenum. My- cotoxigenic species, including A. flavus, A. ochraceus, A. westerdijkiae, A. tubingensis, and P. citrinum, were also detected throughout the samples. Although mycotoxins were not detected in the samples, mycotoxigenic potential of A. flavus, A. ochraceus, and A. westerdijkiae isolates were confirmed. These results show that low temperatures (-20°C, 0°C, or 4°C) and/or high surrounding RH (>93%) are not safe environments for storage of dried red peppers as fungal growth can occur under these conditions.

Evaluation of Barley and Wheat Germplasm for Resistance to Head Blight and Mycotoxin Production by Fusarium asiaticum and F. graminearum

Seul Gi Baek(Seul Gi Baek),Jin Ju Park(Jin Ju Park),Sosoo Kim(Sosoo Kim),Mi-Jeong Lee(Mi-Jeong Lee),Ji-Seon Paek(Ji-Seon Paek),Jangnam Choi(Jangnam Choi),Ja Yeong Jang(Ja Yeong Jang),Jeomsoon Kim(Jeom 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.6

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.

Mycobiota of ground red pepper and their aflatoxigenic potential

Hyeonheui Ham,Sosoo Kim,Min-Hee Kim,Soohyung Lee,Sung Kee Hong,Jae-Gee Ryu,Theresa Lee 한국미생물학회 2016 The journal of microbiology Vol.54 No.12

To investigate contamination of ground red pepper with fungi and mycotoxin, we obtained 30 ground red pepper samples from 15 manufacturers in the main chili-pepper-producing areas in Korea. Fungal contamination was evaluated by spreading diluted samples on potato dextrose agar plates. The total fungi counts ranged from 0 to 7.3 × 103 CFU/g. In the samples, the genus Aspergillus had the highest incidence, while Paecilomyces was isolated most frequently. The next most frequent genera were Rhizopus, Penicillium, Cladosporium, and Alternaria. Within Aspergillus, A. ruber was predominant, followed by A. niger, A. amstelodami, A. ochraceus, A. terreus, A. versicolor, A. flavus, and A. fumigatus. The samples were analyzed for aflatoxins, ochratoxin A, and citrinin by ultraperfomance liquid chromatography (UPLC) with a fluorescence detector. Ochratoxin A was detected from three samples at 1.03‒2.08 μg/kg, whereas no aflatoxins or citrinin were detected. To test the potential of fungal isolates to produce aflatoxin, we performed a PCR assay that screened for the norB-cypA gene for 64 Aspergillus isolates. As a result, a single 800-bp band was amplified from 10 A. flavus isolates, and one Aspergillus sp. isolate. UPLC analyses confirmed aflatoxin production by nine A. flavus isolates and one Aspergillus sp. isolate, which produced total aflatoxins at 146.88‒909.53 μg/kg. This indicates that continuous monitoring of ground red pepper for toxigenic fungi is necessary to minimize mycotoxin contamination.

맥류 종자의 페룰산(ferulic acid) 함량과 붉은곰팡이 저항성

백슬기(Seul Gi Baek),김소수(Sosoo Kim),장자영(Ja Yeong Jang),김점순(Jeomsoon Kim),이데레사(Theresa Lee) 한국식물병리학회 2020 식물병연구 Vol.26 No.4

페룰산 함량이 붉은곰팡이병과 곰팡이독소 저항성 곡류 육종의 선발지표가 될 수 있는지 알기 위해 밀, 보리, 벼 육성 품Table 4. Comparison of barley and wheat for trichothecenes produced by head blight pathogens Pathogena Trichothecene level (μg/g)b t value P-value Wheat Barley Fg(PH-1)-DON 3.86±2.92 6.16±0.28 -2.12051 0.078 Fg(Z34)-DON 3.48±2.62 4.77±2.07 -0.85405 0.426 Fa(W1D)-DON 4.41±0.77 4.75±0.73 -0.74320 0.485 Fa(#73)-NIV 3.04±2.54 5.90±0.60 -2.97238 0.025 Mean 3.69±1.51 5.40±0.40 -2.64047 0.039 aSpecies (isolate name)-trichothecene chemotype: Fg, Fusarium graminearum; Fa, F. asiaticum; DON, deoxynivalenol; NIV, nivalenol. bCalculated as a mean of trichothecene levels±standard deviation. Fig. 2. Trichothecenes produced by head blight pathogens in barley and wheat cultivars and ferulic acid content. The cultivars with w and b indicate wheat and barley, respectively. The pathogen names appear in parentheses. DON, deoxynivalenol; NIV, nivalenol; Mean, mean of toxin levels; FA, ferulic acid. Research in Plant Disease Vol. 26 No. 4 255 종 80점의 페룰산 함량을 조사하였다. 페룰산 함량은 보리 20품종이 1.66‒2.77 mg/g, 밀 40품종이 0.56‒1.53 mg/g이었으며 벼20품종은 0.91‒2.13 mg/g이었다. 이 중 페룰산 함량이 다른 밀과보리 각 7품종을 선정하여 F. graminearum과 F. asiaticum 각 2균주의 붉은곰팡이병과 독소 생성량을 분석하였다. 밀 품종의 평균 병원성은 페룰산 함량이 높은 보리에 비해 유의하게 낮았고밀 품종 간에는 상관관계가 없었다. 곰팡이독소도 병원성과 같이 페룰산 함량이 낮은 밀이 보리보다 생성량이 낮았다. 그러나보리에서는 F. asiaticum 균주의 병원성과 독소 생성량이 페룰산 함량과 음의 상관관계를 나타내었다. 이 결과는 페룰산 함량이 밀과 보리에서 F. graminearum과 F. asiaticum에 의한 붉은곰팡이병과 독소 생성에 저항성 요인이 아님을 보여준다. In order to find if a ferulic acid (FA) can be used as a selection index in cereal breeding for resistance to head blight and mycotoxin production, we analyzed FA in the grains of 80 cultivars of barley, rice, and wheat. FA content ranged 1.66-2.77 mg/g in barley (n=20), 0.56-1.53 mg/g in wheat (n=40), and 0.91-2.13 mg/g in rice (n=20). Among these, 7 cultivars each of barley and wheat with different FA content were tested for head blight and mycotoxin production by 2 Fusarium graminearum and 2 F. asiaticum strains. Mean pathogenicity of the wheat cultivars was significantly less than that of barley with higher FA and among wheat cultivars, there was no correlation between FA content and pathogenicity. Mycotoxin production was also lower in the wheat than in the barley as pathogenicity. However, pathogenicity and toxins produced by F. asiaticum were negatively correlated with FA content in barley. These results indicate that FA is not a resistance factor to head blight by F. asiaticum and F. graminearum or its mycotoxin production in barley and wheat.

Characterization of Nivalenol-Producing Fusarium asiaticum That Causes Cereal Head Blight in Korea

Ja Yeong Jang,Seul Gi Baek,Jung-Hye Choi,Sosoo Kim,김점순,김다운,윤성환,이데레사 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.6

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.

후자린산(Fusaric acid) 생성 Fusarium 종의 신속 검출 PCR

이데레사,김소수,함현희,이수형,홍성기,류재기,Lee, Theresa,Kim, Sosoo,Busman, Mark,Proctor, Robert H.,Ham, Hyeonhui,Lee, Soohyung,Hong, Sung Kee,Ryu, Jae-Gee 한국식물병리학회 2015 식물병연구 Vol.21 No.4

후자린산은 Fusarium이 생성하는 독소로서 다른 Fusarium 독소와 함께 독성을 증진시킬 수 있다. 후자린산 독소를 특이적으로 검출하기 위해 후자린산의 생합성유전자 중 전사인자인 FUB10을 증폭하는 프라이머를 제작하였다. Fub10-f와 Fub10-r 프라이머쌍으로 PCR을 수행했을 때, F. oxysporum, F. proliferatum, F. verticillioides, F. anthophilum, F. bulbicola, F. circinatum, F. fujikuroi, F. redolens, F. sacchari, F. subglutinans, F. thapsinum에서 약 550 bp의 단일밴드가 증폭되었으며 이들은 모두 후자린산을 생성하는 것으로 알려졌다. 반면 트라이코쎄신을 생성하는 종에서는 FUB10 특이 밴드가 증폭되지 않았다. 후자린산은 푸모니신을 생성하는 종에서 함께 생성될 수 있기 때문에 FUB10 프라이머와 푸모니신 생합성유전자인 FUM1 프라이머를 이용한 multiplex PCR을 수행하였다. 그 결과 푸모니신 생성종인 F. proliferatum과 F. verticillioides에서 밴드가 모두 증폭되었으며 이는 두 가지 독소를 생성할 수 있는 종에서 동시 검출이 가능함을 시사하였다. Fusaric acid is a mycotoxin produced by species of the fungus Fusarium and can act synergistically with other Fusarium toxins. In order to develop a specific detection method for fusaric acid-producing fungus, PCR primers were designed to amplify FUB10, a transcription factor gene in fusaric acid biosynthetic gene cluster. When PCR with Fub10-f and Fub10-r was performed, a single band (~550 bp) was amplified from F. oxysporum, F. proliferatum, F. verticillioides, F. anthophilum, F. bulbicola, F. circinatum, F. fujikuroi, F. redolens, F. sacchari, F. subglutinans, and F. thapsinum, all of which were known for fusaric acid production. Whereas the FUB10 specific band was not amplified from Fusarium species known to be trichothecene producer. Because production of fusaric acid can co-occur in species that also produce fumonisin mycotoxins, we developed a multiplex PCR assay using the FUB10 primers as well as primers for the fumonisin biosynthetic gene FUM1. The assay yielded amplicons from fumonisin producers such as F. proliferatum and F. verticillioides, allowing for the simultaneous detection of species with the genetic potential to produce both types of mycotoxins.

Characterization of Nivalenol-Producing Fusarium asiaticum That Causes Cereal Head Blight in Korea

Jang, Ja Yeong,Baek, Seul Gi,Choi, Jung-Hye,Kim, Sosoo,Kim, Jeomsoon,Kim, Da-Woon,Yun, Sung-Hwan,Lee, Theresa The Korean Society of Plant Pathology 2019 Plant Pathology Journal Vol.35 No.6

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.

Characterization of Bacillus amyloliquefaciens DA12 Showing Potent Antifungal Activity against Mycotoxigenic Fusarium Species

Lee, Theresa,Park, Dami,Kim, Kihyun,Lim, Seong Mi,Yu, Nan Hee,Kim, Sosoo,Kim, Hwang-Yong,Jung, Kyu Seok,Jang, Ja Yeong,Park, Jong-Chul,Ham, Hyeonheui,Lee, Soohyung,Hong, Sung Kee,Kim, Jin-Cheol The Korean Society of Plant Pathology 2017 Plant Pathology Journal Vol.33 No.5

In an attempt to develop a biological control agent against mycotoxigenic Fusarium species, we isolated Bacillus amyloliquefaciens strain DA12 from soil and explored its antimicrobial activities. DA12 was active against the growth of mycotoxigenic F. asiaticum, F. graminearum, F. proliferatum, and F. verticillioides both in vitro and in planta (maize). Further screening using dual culture extended the activity range of strain DA12 against other fungal pathogens including Botrytis cinerea, Colletotrichum coccodes, Endothia parasitica, Fusarium oxysporum, Raffaelea quercus-mongolicae, and Rhizoctonia solani. The butanol extract of the culture filtrate of B. amyloliquefaciens DA12 highly inhibited the germination of F. graminearum macroconidia with inhibition rate 83% at a concentration of $31.3{\mu}g/ml$ and 100% at a concentration of $250{\mu}g/ml$. The antifungal metabolite from the butanol extract was identified as iturin A by thin layer chromatography-bioautography. In addition, volatile organic compounds produced by DA12 were able to inhibit mycelial growth of various phytopathogenic fungi. The volatile compounds were identified as 2-heptanone, 5-methyl heptanone and 6-methyl heptanone by gas chromatography-mass spectrometry (GC-MS) analysis. These results indicate that the antagonistic activity of Bacillus amyloliquefaciens DA12 was attributable to iturin A and volatile heptanones, and the strain could be used as a biocontrol agent to reduce the development of Fusarium diseases and mycotoxin contamination of crops.