• 한국식물병리학회지
• /
• 제3권3호
• /
• pp.198-202
• /
• 1987

밀 보리에서 crown root rot 및 leaf blotch를 이르키는 Helminthosporium sativum의 독소물질을 분리하였다. 이는 독소물질에 대한 어떤 손상도 없이 C-18 column으로 분리되었으며, 실험적으로 가능한 inhibitor를 제거하였다. Lettuce 성장과 독소물질의 농도의 반응에는 semi-log 표에서 비례하였다. 또한 pathogen host인 밀 보리의 뿌리 성장에 사용한 결과 Lettuce의 반응과 동일한 결과를 얻었다. 또한, pathogen host인 밀 보리의 뿌리 성장에 사용한 결과 Lettuce의 반응과 동일한 결과를 얻었다. 독소물질과 식물의 반응을 측정하여 dilution end-points.의 결과로, 직접적으로 독소물질의 농도를 측정하는 방법을 개발하였다. (Y=a log x+b)의 공식과 통계처리로 사용하여 얻은 a와 b의 의미를 토론하였다.

• 식물병연구
• /
• 제12권3호
• /
• pp.185-188
• /
• 2006

2005년 전남 나주와 광주의 멜론 재배포장에서 잎맥을 따라 갈색으로 변색되면서 시드는 증상이 관찰되었고, 과실 표면에는 점무늬의 수침상이 형성되며 과실 내부는 갈색으로 썩는 증상이 관찰되었다. 잎과 과실의 병반부로부터 2개의 세균을 분리하여 생리생화학적 실험, 유전적 실험 및 병원성 실험 결과 Acidovorax avenae subsp. citrulli로 동정되었다. 이 보고는 국내에서 최초이며, 이 병을 멜론 과실썩음병으로 명명할 것을 제안한다.

• The Plant Pathology Journal
• /
• 제36권1호
• /
• pp.29-42
• /
• 2020

Acidovorax citrulli causes bacterial fruit blotch in Cucurbitaceae, including watermelon. Although A. citrulli is a seed-borne pathogen, it can cause diverse symptoms in other plant organs like leaves, stems and fruits. To determine the infection routes of A. citrulli, we examined the virulence of six isolates (Ac0, Ac1, Ac2, Ac4, Ac8, and Ac11) on watermelon using several inoculation methods. Among six isolates, DNA polymorphism reveals that three isolates Ac0, Ac1, and Ac4 belong to Clonal Complex (CC) group II and the others do CC group I. Ac0, Ac4, and Ac8 isolates efficiently infected seeds during germination in soil, and Ac0 and Ac4 also infected the roots of watermelon seedlings wounded prior to inoculation. Infection through leaves was successful only by three isolates belonging to CC group II, and two of these also infected the mature watermelon fruits. Ac2 did not cause the disease in all assays. Interestingly, three putative type III effectors (Aave_2166, Aave_2708, and Aave_3062) with intact forms were only found in CC group II. Overall, our results indicate that A. citrulli can infect watermelons through diverse routes, and the CC grouping of A. citrulli was only correlated with virulence in leaf infection assays.

• 한국식물병리학회지
• /
• 제11권4호
• /
• pp.380-382
• /
• 1995

Yellow spot or blotch symptoms on the upper surface of leaf, without the production of velvet-like fungi on the lower surface of leaf as in the gray mold of tomato caused by Cladosporium fulvum, were observed in tomato (cv. Seokwang) plants in May, 1995, in a vinyl-house of the experimental plot of Gyeongnam Provincial Rural Development Administration, Chinju, Gyeongnam, Korea. We identified this disease as powdery mildew of tomato caused by Oidiopsis taurica (L v.) Arnaud (=Leveillula taurica), which was new to Korea. Conidia of the fungus were borne on uni- or bi-septated conidiophores which were developed through the stomata of the tomato leaf. The conidia were slender, clavate and variable in size (31~111.6$\times$13.1 ${\mu}{\textrm}{m}$). The fungal conidia isolated from tomato leaves were inoculated to tomato plants, and the occurrence of the same disease was confirmed based on the symptomatology and the morphology of the pathogen reisolated.

• The Plant Pathology Journal
• /
• 제35권6호
• /
• pp.585-597
• /
• 2019

A disease forecast model for Marssonina blotch of apple was developed based on field observations on airborne spore catches, weather conditions, and disease incidence in 2013 and 2015. The model consisted of the airborne spore model (ASM) and the daily infection rate model (IRM). It was found that more than 80% of airborne spore catches for the experiment period was made during the spore liberation period (SLP), which is the period of days of a rain event plus the following 2 days. Of 13 rain-related weather variables, number of rainy days with rainfall ≥ 0.5 mm per day (L_day), maximum hourly rainfall (P_max) and average daily maximum wind speed (W_avg) during a rain event were most appropriate in describing variations in airborne spore catches during SLP (S_i) in 2013. The ASM, Ŝ_i = 30.280+5.860×L_day×P_max-2.123×L_day×P_max×W_avg was statistically significant and capable of predicting the amount of airborne spore catches during SLP in 2015. Assuming that airborne conidia liberated during SLP cause leaf infections resulting in symptom appearance after 21 days of incubation period, there was highly significant correlation between the estimated amount of airborne spore catches (Ŝ_i) and the daily infection rate (R_i). The IRM, ${\hat{R}}_i$ = 0.039+0.041×Ŝ_i, was statistically significant but was not able to predict the daily infection rate in 2015. No weather variables showed statistical significance in explaining variations of the daily infection rate in 2013.

• The Plant Pathology Journal
• /
• 제34권1호
• /
• pp.59-64
• /
• 2018

Bacteriophages of Acidovorax citrulli, the causal agent of bacterial fruit blotch, were isolated from 39 watermelon, pumpkin, and cucumber leaf samples collected from various regions of Korea and tested against 18 A. citrulli strains. Among the six phages isolated, ACP17 forms the largest plaque, and exhibits the morphology of phages in the Myoviridae family with a head diameter of $100{\pm}5nm$ and tail length of $150{\pm}5nm$. ACP17 has eclipse and latent periods of $25{\pm}5min$ and $50{\pm}5min$, respectively, and a burst size of 120. The genome of ACP17 is 156,281 base pairs with a G + C content of 58.7%, 263 open reading frames, and 4 transfer RNA genes. Blast search and phylogenetic analysis of the major capsid protein showed that ACP17 has limited homology to two Stentrophomonas phages, suggesting that ACP17 is a new type of Myoviridae isolated from A. citrulli.

• The Plant Pathology Journal
• /
• 제39권3호
• /
• pp.235-244
• /
• 2023

Acidovorax citrulli (Ac) is a phytopathogenic bacterium that causes bacterial fruit blotch (BFB) in cucurbit crops, including watermelon. However, there are no effective methods to control this disease. YggS family pyridoxal phosphate-dependent enzyme acts as a coenzyme in all transamination reactions, but its function in Ac is poorly understood. Therefore, this study uses proteomic and phenotypic analyses to characterize the functions. The Ac strain lacking the YggS family pyridoxal phosphate-dependent enzyme, AcΔyppAc(EV), virulence was wholly eradicated in geminated seed inoculation and leaf infiltration. AcΔyppAc(EV) propagation was inhibited when exposed to L-homoserine but not pyridoxine. Wild-type and mutant growth were comparable in the liquid media but not in the solid media in the minimal condition. The comparative proteomic analysis revealed that YppAc is primarily involved in cell motility and wall/membrane/envelop biogenesis. In addition, AcΔyppAc(EV) reduced biofilm formation and twitching halo production, indicating that YppAc is involved in various cellular mechanisms and possesses pleiotropic effects. Therefore, this identified protein is a potential target for developing an efficient anti-virulence reagent to control BFB.

• 한국약용작물학회지
• /
• 제4권3호
• /
• pp.236-240
• /
• 1996

1. 작약(芍藥)의 지상부(地上部)에 기생(寄生)하는 주요 병원균(病原菌)은 점무늬병균 등 7종(種)이었으며 점 무늬병은 잎, 검은무늬병은 줄기, 흰가루병은 잎과 줄기 등 지상부 전체에 발생이 심하였다. 2. 작약(芍藥)에는 점무늬병과 흰가루병이 우점종(優占種)이었고, 각각 4월 하순, 5월 중순부터 발생되기 시작하여 5월 하순 이후는 급격히 증가하였으며 의성작약(義城芍藥)이 영천종(永川種)보다 발병율이 높았다. 3. 시기별(時期別) 작약(芍藥) 지상부(地上部) 고사율(枯死率)은 95년의 경우 5월 하순부터 고사(枯死)하기 시작하여 6월 하순에 15.3%로 그 이후부터는 급격히 증가하여 8월 상순에는 50.6%가 고사(枯死)하였으며 5, 6월의 조기고사(早期枯死)는 주로 흰가루병 때문이었다.

• The Plant Pathology Journal
• /
• 제22권4호
• /
• pp.375-380
• /
• 2006

In the survey from 1992 to 2000, twenty-eight parasitic diseases were observed in major apple producing areas in Korea. The predominant apple diseases were white rot(Botryosphaeria dothidea), Marssonina blotch(Marssonina mali), Valsa canker(Valsa ceratosperma), Alternaria leaf spot(Alternaria mali), and bitter rot(Collectotrichum gloeosporioides and C. acutatum). Apple scab that reappeared in 1990 after disappearance for 15 years was disappeared again since 1997. A viroid disease(caused by apple scar skin viroid) was newly found in this survey. The five diseases, fire blight(Erwinia amylovora), black rot(Botryosphaeria obtusa), scab(Cladosporium carpophilum), Monochaetia twig blight(Monochaetia sp.), and brown leaf spot(Hendersonia mali), which had once described in 1928 but no further reports on their occurrence, were not found in this survey. However, blossom blight(Monilinia mali), brown rot(Monilinia fructigena), and pink rot(Trichothecium roseum), which did not occur on apple after mid 1970s, were found in this survey.

• The Plant Pathology Journal
• /
• 제40권2호
• /
• pp.115-124
• /
• 2024

Citrus cultivation plays a pivotal role, making a significant contribution to global fruit production and dietary consumption. Accurate identification of viral pathogens is imperative for the effective management of plant viral disease in citrus crops. High-throughput sequencing serves as an alternative approach, enabling comprehensive pathogen identification on a large scale without requiring pre-existing information. In this study, we employed HTS to investigate viral pathogens infecting citrus in three different regions of South Korea: Jejudo (Jeju), Wando-gun (Wando), and Dangjin-si (Dangjin). The results unveiled diverse viruses and viroids that exhibited regional variations. Notably, alongside the identification of well-known citrus viruses such as satsuma dwarf virus, citrus tatter leaf virus, and citrus leaf blotch virus (CLBV), this study also uncovered several viruses and viroids previously unreported in Korean citrus. Phylogenetic analysis revealed that majority of identified viruses exhibited the closest affilations with isolates from China or Japan. However, CLBV and citrus viroid-I-LSS displayed diverse phylogenetic positions, reflecting their regional origins. This study advances our understanding of citrus virome diversity and regional dynamics through HTS, emphasizing its potential in unraveling intricate viral pathogens in agriculture. Consequently, it significantly contributes to disease management strategies, ensuring the resilience of the citrus industry.