• The Plant Pathology Journal
• /
• 제26권3호
• /
• pp.231-237
• /
• 2010

The heat-inactivated (at $121^{\circ}C$ for 20 min) conidial suspension of Bipolaris cactivora (HICS) was evaluated for the control of Bipolaris stem rot of cactus caused by B. cactivora. Severe rot symptoms were developed on the cactus stem discs inoculated with B. cactivora from 5 days after inoculation. However, only small brownish spots developed on the stem discs treated with HICS 2 days prior to the pathogen inoculation. HICS also reduced symptom development on cactus stem discs inoculated with other fungal pathogens such as Alternaria alternata, Colletotrichum gloeosporioides, and Fusarium oxysporum, suggesting its disease-inhibitory efficacy may not be pathogen-specific. HICS significantly reduced severities of the stem rot disease on several cactus species including Hylocereus trigonus, Cereus peruvianus, Chamaecereus silvestrii and Gymnocalycium mianovichii, but not on Cereus tetragonus. Extensive wound periderms were formed in the stem tissues of inoculation and/or wounding sites on C. peruvianus treated with HICS alone or prior to the pathogen inoculation, but not on C. tetragonus, indicating the structural modifications may be related to the mechanism of disease suppression by HICS. HICS also reduced the disease development on the grafted cactus (H. trigonus stock and G. mianovichii scion) with the control efficacy nearly equivalent to the application of a commercial fungicide. All of these results suggest HICS can be used as an environmental-friendly agent for the control of the cactus stem disease.

• The Plant Pathology Journal
• /
• 제29권4호
• /
• pp.446-450
• /
• 2013

The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

• The Plant Pathology Journal
• /
• 제36권2호
• /
• pp.179-184
• /
• 2020

A leaf spot pathogen Alternaria sp. was recovered from jimson weed, tomato, parsley, and coriander collected during surveys of blight diseases on Solanaceae and Apiaceae in Algeria. This species produced large conidial body generating long apical beaks that tapered gradually from a wide base to a narrow tip and short conidiophores originating directly from the agar surface. This species exhibited morphological traits similar to that reported for Alternaria crassa. The identification of seven strains from different hosts was confirmed by sequence analyses at the glyceraldehyde-3-phosphate dehydrogenase, RNA polymerase second largest subunit, and translation elongation factor 1-alpha loci. Further the pathogen was evaluated on jimson weed, coriander, parsley, and tomato plants, and this fungus was able to cause necrotic lesions on all inoculated plants. A. crassa is reported for the first time as a new species of the Algerian mycoflora and as a new potential pathogen for cultivated hosts.

• 식물병연구
• /
• 제17권1호
• /
• pp.99-101
• /
• 2011

자낭균인 Taphrina wiesneri는 한국의 공원과 가로수에 주로 식재되는 왕벚나무에 빗자루병을 일으키는 병원균이다. 한국과 일본에서 분리한 13개의 병원균에 대해 18S rDNA 염기서열 분석을 통한 계통학적 분석과 rDNA-IGS 영역에 대한 RFLP 분석을 실시하였다. 18S rDNA 염기서열 분석을 통한 계통도 분석결과 병원균은 2그룹으로 분류되었다. Hha I 제한효소를 이용한 rDNA-IGS 영역에 대한 RFLP 분석결과 B, C, D, G 4개의 패턴으로 나타났으며, 그중 G 패턴은 새로운 패턴이었다.

• The Plant Pathology Journal
• /
• 제19권6호
• /
• pp.294-300
• /
• 2003

Bacterial strains were isolated from diseased samples of shoot blight collected from different pear growing orchards of Chuncheon, Korea from 1995 to 1998. Forty-nine strains showed their pathogenicity on immature fruit and shoot of pear. Microbiological, physiological, and biochemical tests were performed on these pathogenic strains. One strain, designated as WT3 in this study, was selected as a representative strain as it was collected from the first outbreak area in Jichonri, Chuncheon in 1995. Further detailed characterization of the strain WT3 was done by PCR amplification using specific primers described previously for distinguishing Erwinia pyrifoliae from its close pathogen Erwinia amylovora. Based on phenotypical, biochemical, and molecular analyses, strain WT3 was identified as a shoot blight pathogen which was the same as E. pyrifoliae Ep16 previously described by a German group in 1999.

• Mycobiology
• /
• 제44권2호
• /
• pp.93-98
• /
• 2016

A new leaf spot disease was observed on leaves of Rheum palmatum (Chinese rhubarb) in Northwest China (Gansu Province) starting in 2005. A Septoria-like fungus was isolated and completion of Koch's postulates confirmed that the fungus was the casual agent of the leaf spot disease. Morphology and molecular methods were combined to identify the pathogen. The fungus produced conidiomata pycnidia and the conidia were 2~5 septate, $61.2{\sim}134.1{\mu}m$ in length and $3.53{\sim}5.3{\mu}m$ in width, which is much larger than the known Spetoria species that infects Polygonaceae species. Phylogenic analysis of the internal transcribed spacer region confirmed that this Septoria-like fungus is within the Septoria genus but distinct from known Septoria species. Together, these morphological and phylogenetic data support that the R. palmatum infecting Septoria strain is a newly-described plant pathogenic species.

• The Plant Pathology Journal
• /
• 제35권1호
• /
• pp.1-10
• /
• 2019

Wheat blast occurred in Bangladesh for the first time in Asia in 2016. It is caused by a fungal pathogen, Magnaporthe oryzae Triticum (MoT) pathotype. In this review, we focused on the current status of the wheat blast in regard to host, pathogen, and environment. Despite the many efforts to control the disease, it expanded to neighboring regions including India, the world's second largest wheat producer. However, the disease occurrence has definitely decreased in quantity, because of many farmers chose to grow alternate crops according to the government's directions. Bangladesh government planned to introduce blast resistant cultivars but knowledges about genetics of resistance is limited. The genome analyses of the pathogen population revealed that the isolates caused wheat blast in Bangladesh are genetically close to a South American lineage of Magnaporthe oryzae. Understanding the genomes of virulent strains would be important to find target resistance genes for wheat breeding. Although the drier winter weather in Bangladesh was not favorable for development of wheat blast before, recent global warming and climate change are posing an increasing risk of disease development. Bangladesh outbreak in 2016 was likely to be facilitated by an extraordinary warm and humid weather in the affected districts before the harvest season. Coordinated international collaboration and steady financial supports are needed to mitigate the fearsome wheat blast in South Asia before it becomes a catastrophe.

• The Plant Pathology Journal
• /
• 제35권5호
• /
• pp.530-537
• /
• 2019

Fuji, a major apple cultivar in Korea, is susceptible to white rot. Apple white rot disease appears on the stem and fruit; the development of which deteriorates fruit quality, resulting in decreases in farmers' income. Thus, it is necessary to characterize molecular markers related to apple white rot resistance. In this study, we screened for differentially expressed genes between uninfected apple fruits and those infected with Botryosphaeria dothidea, the fungal pathogen that causes white rot. Antimicrobial tests suggest that a gene expression involved in the synthesis of the substance inhibiting the growth of B. dothidea in apples was induced by pathogen infection. We identified seven transcripts induced by the infection. The seven transcripts were homologous to genes encoding a flavonoid glucosyltransferase, a metallothionein-like protein, a senescence-induced protein, a chitinase, a wound-induced protein, and proteins of unknown function. These genes have functions related to responses to environmental stresses, including pathogen infections. Our results can be useful for the development of molecular markers for early detection of the disease or for use in breeding white rotresistant cultivars.

• 생명과학회지
• /
• 제21권2호
• /
• pp.227-234
• /
• 2011

Pseudomonas syringae pv. tabaci는 숙주인 담배에 감염하여 들불병(wild fire)을 일으키는 식물 병원성 세균이다. 이 세균의 pathogenicity island (PAI)는 Type III secretion system 및 병원성 유전자들을 암호화하고 있으며, 병원성 조절에 있어 핵심적인 역할을 한다. 최근 식물 병원성 세균인 Ralstonia solanacearum에서 식물 세포 접촉을 매개로 하여 hrp gene cluster를 양성조절하는 PrhA (plant regulator of hrp) receptor가 발견되었다. 본 연구에서는 P. syringae에서 식물세포에 의해 hrp 유전자가 유도되는지 확인하기 위해, prhA 유사체를 동정하고 PrhA 결실돌연변이주(BL11)를 구축하였다. BL11은 숙주 감염 실험에서 병원성이 현저히 감소하였고, 식물 세포현탁액에서 hrpA 유전자의 발현수준이 hrp 유도배지에서 보다 3배 더 높게 나타났다. 이러한 결과들을 근거로 PrhA가 식물세포접촉에 의한 조절에 중요한 역할을 한다는 것을 확인하였으며, hrpA-gfp reporter fusion을 사용하여 이를 다시 검증하였다.

• The Plant Pathology Journal
• /
• 제24권2호
• /
• pp.183-190
• /
• 2008

Plant-cell-wall-degrading enzymes (PCWDEs) of Pectobacterium carotovorum subsp. carotovorum are the key virulence factor in pathogenesis of soft rot disease of vegetables. The production of PCWDEs is controlled in a cell density dependent manner to avoid the premature production of PCWDEs and subsequent activation of plant defense. N-oxoacyl-homoserine lactone (OHL) is essential for quorum sensing in the soft rot pathogen and the expI gene is responsible for OHL production. The ExpI homolog isolated from P. carotovorum subsp. carotovorum SL940 had 94% identity with ExpI of E. carotovora subsp. carotovora scc3193 and 74% identity with Carl of E. carotovora subsp. atroseptica. The transgenic plants that express exp I uner the control of CaMV35S promoter were able to produce diffusible OHL. Transgenic plants producing OHL were very resistant to the infection of P. carotovorum subsp. carotovorum. Since the PR1 gene was strongly induced and NPR1 and NPR4 were induced weakly in transgenic plants compared to the wild type, salicylic acid-dependent pathways is likely involved in the resistance to the soft rot pathogen P. carotovorum subsp. carotovorum in ExpI transgenic plants.