• 식물병연구
• /
• 제29권3호
• /
• pp.243-250
• /
• 2023

한국은 오랫동안 벼 도열병 방제 연구를 진행해왔고 다양한 방제 체계를 구축하고 있으나 벼 도열병은 지속적으로 변이가 이뤄지기 때문에 항상 벼 도열병에 대한 예찰과 방제를 위한 연구가 필요하다. 북한은 남한으로의 벼 도열병 원인균이 유입될 수 있는 주요 경로 중 하나임으로 북한에서 발생하는 벼 도열병의 균주 분포와 다양성 연구는 한국에서 발생할 수 있는 벼 도열병 방제 연구에 중요한 자료일 수밖에 없다. 2018년도 철원과 수원에서 분리한 균주는 KI와 KJ의 점유율이 유사한 수준이었으나 이후 진행된 연구 결과에서는 레이스 분포에 변화가 나타났다. 수원은 2018년 KI/KJ 레이스의 점유율이 유사했으나 2019년 2020년으로 갈수록 KJ레이스의 점유율이 높아졌고 전주의 경우 2019년 KJ/KI 레이스 점유율이 역전된 후 2020년까지 KJ 레이스의 점유율은 높게 유지되었다. 철원의 경우 2018년부터 2019년까지 KJ/KI 레이스 비율이 유사하였는데 2020년에는 거의 KJ 레이스만 분포하는 것을 발견하였다. 반면 고위도 지역인 중국 내 북한 접경지역인 단둥과 연길에서 분리한 도열병균의 레이스 분포를 비교 분석하면, 국내의 도열병 레이스 변화와 달리 2021년부터 2022년까지 중국의 북한 접경지역인 단둥과 연길에서는 KI 레이스가 우점이었다. 단인자 계통 저항성 검정 실험에서는 IRBL9-W, IRBLIR-24 계통이 국내와 고위도 북한 접경지역 모두 공통의 저항성원으로 분류되었다. 비록 남한 및 중국 내 북한 접경지역에서의 벼도열병균의 레이스 분석 연도의 차이가 있어 직접적인 비교는 어려우나 중국의 접경지역과 남한의 벼도열병균 레이스의 지역간 비교는 도열병 방제 체계 구축에 중요한 자료로 판단된다.

• Journal of Plant Biotechnology
• /
• 제4권1호
• /
• pp.1-6
• /
• 2002

Plants have developed a sophisticated battery of defence responses to protect themselves against attempted pathogen ingress. Manipulation of these defence mechanisms may provide significant opportunities for crop improvement. While plant resistance genes have had a long service history in plant breeding, they possess significant limitations. Recent advances are now providing significant insights into strategies designed to increase the field durability of this class of genes. Hypersensitive cell death is a common feature underlying the deployment of plant defence responses against biographic pathogens. In contrast, necrotrophic pathogens actively kill plant cells. Recently, transgenic plants have been developed that either promote or suppress cell death, providing resistance against either biotrophic or necrotrophic pathogens respectively. Methyl-jasmonate is a key signalling molecule in the establishment of resistance against some fungal pathogens. Increasing the concentration of this molecule in plant cells has been shown to increase resistance against Botrytis cineria, without significantly imparting plant growth or development. Due to the multifarious infection strategies employed by plant pathogens, how-ever, it is unlikely a single commercial product will prove a panacea for global disease control. Future stategies will more likely entail an integrated disease management approach.

• 한국식품위생안전성학회지
• /
• 제31권6호
• /
• pp.458-464
• /
• 2016

오디를 포함한 베리류의 건강 기능성이 알려지면서 생산량 증가 및 가공식품 개발이 활발해지고 있지만 베리류 과실의 특성상 상처 입거나 무르기 쉬워 생과로 유통되기 보다는 다양한 형태의 가공품으로 유통되고 있다. 베리류를 원료로 식물발효액을 제조하기도 하는데 대부분 소규모 이루어져 원료의 안전성 및 제조과정에 대한 위생관리가 시급하다. 본 연구는 오디 발효액 제조에 사용되는 원물이 유해 세균에 오염되었을 경우와 발효액으로 소량 포장되는 단계에서 유해 세균에 오염되었을 경우에 오디 발효액 발효과정 중 그리고 오염 발효액 보관과정 중 오염세균의 세균수 변화를 조사하기 위해 수행되었다. 오디 발효액이 발효되는 동안 원물에 접종된 E. coli는 시간이 지나면서 감소하는 양상이었다. 특히 오디 원물의 무게 대비 100%로 설탕을 혼합한 처리구 보다는 80%로 혼합한 처리구에서 E. coli의 세균수 감소가 급격하였는데, 설탕을 원물 무게의 80%로 혼합하였을 때 발효과정 중 생기는 총 산도가 100% 혼합처리구보다 높음으로써 결과적으로 발효액의 pH가 낮아지게 되어 발생한 결과인 것으로 판단된다. 발효가 완료되어 발효액으로 제품화되는 과정에서 식중독세균에 오염되었을 경우에는 접종 균주별로 조금씩 다른 세균수 감소 양상을 보였지만 대체적으로 보관시간이 지남에 따라 감소하는 양상이었고, 특히 $30^{\circ}C$에서 보관하였을 때에는 실험균주 모두 4일 이내에 사멸하였다. 따라서 오디 발효액 제품화시 소량 포장 후 $30^{\circ}C$의 온도에서 일주일 정도 보관하는 것이 오디 발효액의 미생물학적 안전성을 높이는데 도움이 될 것으로 판단된다.

• The Plant Pathology Journal
• /
• 제30권4호
• /
• pp.397-406
• /
• 2014

Maize is a socioeconomically important crop in many countries. Recently, a high incidence of stalk rot disease has been reported in several maize fields in Gangwon province. In this report, we show that maize stalk rot is associated with the fungal pathogens Fusarium subglutinans and F. temperatum. Since no fungicides are available to control these pathogens on maize plants, we selected six fungicides (tebuconazole, difenoconazole, fluquinconazole, azoxystrobin, prochloraz and kresoxim-methyl) and examined their effectiveness against the two pathogens. The in vitro antifungal effects of the six fungicides on mycelial growth and colony formation were investigated. Based on the inhibition of mycelial growth, the most toxic fungicide was tebuconazole with 50% effective concentrations ($EC_{50}$) of < $0.1{\mu}g/ml$ and $EC_{90}$ values of $0.9{\mu}g/ml$ for both pathogens, while the least toxic fungicide was azoxystrobin with $EC_{50}$ values of 0.7 and $0.5{\mu}g/ml$ for F. subglutinans and F. temperatum, respectively, and $EC_{90}$ values of > $3,000{\mu}g/ml$ for both pathogens. Based on the inhibition of colony formation by the two pathogens, kresoxim-methyl was the most toxic fungicide with complete inhibition of colony formation at concentrations of 0.1 and $0.01{\mu}g/ml$ for F. subglutinans and F. temperatum, respectively, whereas azoxystrobin was the least toxic fungicide with complete inhibition of colony formation at concentrations > $3,000{\mu}g/ml$ for both pathogens.

• Journal of Ginseng Research
• /
• 제26권3호
• /
• pp.151-158
• /
• 2002

Ginseng (Panax quinquefolius L.) has become one of the most valuable herb crops grown in North America. However, traditional cropping practices are favourable to disease and significant losses due to root disease are common, despite frequent use of fungicides. Seedlots are often contaminated with pathogens, however, little is known about the causes of seed decay and the role of seed pathogens as incitants of root rots. It was shown that both Fusarium spp. and Cylindrocarpon destructans were able to rot seeds and that C. destructans was more virulent than Fusarium spp. on seedling roots. A modified rose bengal agar MRBA) medium (1 g KH$_2$PO$_4$; 0.5 g MgSO$_4$; 50 mg rose bengal; 10 g dextrose; 5 g Bacto peptone; 15 g Bacto agar; 30 mg streptomycin sulfate; 250 mg ampicillin; 10 mg rifampicin; 500mg pentachloronitrobenzene; 500 mg dicloran; and 1 L distilled water) was superior to potato dextrose agar in detecting C. destuctans in diseased roots. Isolation of C. destructans from diseased seedlings arising from seeds sown in replant soil supported the hypothesis that this pathogen is a cause of ginseng replant failure in North America.

• Molecules and Cells
• /
• 제42권9호
• /
• pp.637-645
• /
• 2019

Effector-triggered immunity (ETI) is an effective layer of plant defense initiated upon recognition of avirulence (Avr) effectors from pathogens by cognate plant disease resistance (R) proteins. In rice, a large number of R genes have been characterized from various cultivars and have greatly contributed to breeding programs to improve resistance against the rice blast pathogen Magnaporthe oryzae. The extreme diversity of R gene repertoires is thought to be a result of co-evolutionary history between rice and its pathogens including M. oryzae. Here we show that Pii is an allele of Pi5 by DNA sequence characterization and complementation analysis. Pii-1 and Pii-2 cDNAs were cloned by reverse transcription polymerase chain reaction from the Pii-carrying cultivar Fujisaka5. The complementation test in susceptible rice cultivar Dongjin demonstrated that the rice blast resistance mediated by Pii, similar to Pi5, requires the presence of two nucleotide-binding leucine-rich repeat genes, Pii-1 and Pii-2. Consistent with our hypothesis that Pi5 and Pii are functionally indistinguishable, the replacement of Pii-1 by Pi5-1 and Pii-2 by Pi5-2, respectively, does not change the level of disease resistance to M. oryzae carrying AVR-Pii. Surprisingly, Exo70F3, required for Pii-mediated resistance, is dispensable for Pi5-mediated resistance. Based on our results, despite similarities observed between Pi5 and Pii, we hypothesize that Pi5 and Pii pairs require partially distinct mechanisms to function.

• The Plant Pathology Journal
• /
• 제36권4호
• /
• pp.305-313
• /
• 2020

Host shifting and host expansion of fungal plant pathogens increases the rate of emergence of new pathogens and the incidence of disease in various crops, which threaten global food security. Magnaporthe species cause serious disease in rice, namely rice blast disease, as well as in many alternative hosts, including wheat, barley, and millet. A severe outbreak of wheat blast due to Magnaporthe oryzae occurred recently in Bangladesh, after the fungus was introduced from South America, causing great loss of yield. This outbreak of wheat blast is of growing concern, because it might spread to adjacent wheat-producing areas. Therefore, it is important to understand the host range and population structure of M. oryzae and related species for determining the evolutionary relationships among Magnaporthe species and for managing blast disease in the field. Here, we collected isolates of M. oryzae and related species from various Poaceae species, including crops and weeds surrounding rice fields, in Korea and determined their phylogenetic relationships and host species specificity. Internal transcribed spacer-mediated phylogenetic analysis revealed that M. oryzae and related species are classified into four groups primarily including isolates from rice, crabgrass, millet and tall fescue. Based on pathogenicity assays, M. oryzae and related species can infect different Poaceae hosts and move among hosts, suggesting the potential for host shifting and host expansion in nature. These results provide important information on the diversification of M. oryzae and related species with a broad range of Poaceae as hosts in crop fields.

• The Plant Pathology Journal
• /
• 제38권4호
• /
• pp.313-322
• /
• 2022

Seed-borne pathogens in crops reduce the seed germination rate and hamper seedling growth, leading to significant yield loss. Due to the growing concerns about environmental damage and the development of resistance to agrochemicals among pathogen populations, there is a strong demand for eco-friendly alternatives to synthetic chemicals in agriculture. It has been well established during the last few decades that plant seeds harbor diverse microbes, some of which are vertically transmitted and important for plant health and productivity. In this study, we isolated culturable endophytic bacteria and fungi from soybean seeds and evaluated their antagonistic activities against common bacterial and fungal seed-borne pathogens of soybean. A total of 87 bacterial isolates and 66 fungal isolates were obtained. Sequencing of 16S rDNA and internal transcribed spacer amplicon showed that these isolates correspond to 30 and 15 different species of bacteria and fungi, respectively. Our antibacterial and antifungal activity assay showed that four fungal species and nine bacterial species have the potential to suppress the growth of at least one seed-borne pathogen tested in the study. Among them, Pseudomonas koreensis appears to have strong antagonistic activities across all the pathogens. Our collection of soybean seed endophytes would be a valuable resource not only for studying biology and ecology of seed endophytes but also for practical deployment of seed endophytes toward crop protection.

• Journal of Applied Biological Chemistry
• /
• 제63권3호
• /
• pp.189-195
• /
• 2020

The soybean (Glycine max L.), also known as the soya bean, is an economically important legume species. Pathogens are always major threats for soybean cultivation. Several pathogens negatively affect soybean production. The soybean is also known as a susceptible host to many viruses. Recently, we carried out systematic analyses to identify viruses infecting soybeans using soybean transcriptome data. Our screening results showed that only few soybean transcriptomes contained virus-associated sequences. In this study, we further carried out bioinformatics analyses using a soybean flower bud transcriptome for virus identification, genome assembly, and single nucleotide variations (SNVs). We assembled the genome of Soybean yellow common mosaic virus (SYCMV) isolate China and revealed two SNVs. Phylogenetic analyses using three viral proteins suggested that SYCMV isolate China is closely related to SYCMV isolates from South Korea. Furthermore, we found that replication and mutation of SYCMV is relatively low, which might be associated with flower bud tissue. The most interesting finding was that SYCMV was not detected in the cytoplasmic male sterility (CMS) line derived from the non-CMS line that was severely infected by SYCMV. In summary, in silico analyses identified SYCMV from the soybean flower bud transcriptome, and a nearly complete genome of SYCMV was successfully assembled. Our results suggest that the low level of virus replication and mutation for SYCMV might be associated with plant tissues. Moreover, we provide the first evidence that male sterility might be used to eliminate viruses in crop plants.

• Molecules and Cells
• /
• 제25권3호
• /
• pp.323-331
• /
• 2008

Plants are continually exposed to a variety of potentially pathogenic microbes, and the interactions between plants and pathogenic invaders determine the outcome, disease or disease resistance. To defend themselves, plants have developed a sophisticated immune system. Unlike animals, however, they do not have specialized immune cells and, thus all plant cells appear to have the innate ability to recognize pathogens and turn on an appropriate defense response. Using genetic, genomic and biochemical methods, tremendous advances have been made in understanding how plants recognize pathogens and mount effective defenses. The primary immune response is induced by microbe-associated molecular patterns (MAMPs). MAMP receptors recognize the presence of probable pathogens and evoke defense. In the co-evolution of plant-microbe interactions, pathogens gained the ability to make and deliver effector proteins to suppress MAMP-induced defense responses. In response to effector proteins, plants acquired R-proteins to directly or indirectly monitor the presence of effector proteins and activate an effective defense response. In this review we will describe and discuss the plant immune responses induced by two types of elicitors, PAMPs and effector proteins.