• The Plant Pathology Journal
• /
• 제18권2호
• /
• pp.57-62
• /
• 2002

In vivo expression technology (IVET) has been developed to study bacterial gene expression in Salmonella typhimurium during host infection. The expression of selected genes by IVET has been elevated in vivo but not in vitro. The selected genes turned out to be important for bacterial virulence and/or pathogenicity. IVET depends on a synthetic operon with a promoterless transcriptional fusion between a selection marker gene and a reporter gene. The IVET approach has been successfully adapted in other bacterial pathogens and plant-associated bacteria using different selection markers. Pseudomonas putida suppresses citrus root rot caused by Phytophthora parasitica and enhances citrus seedling growth. The WET strategy was adapted based on a transcriptional fusion, pyrBC'-lacZ, in P. putida to study the bacterial traits important far biocontrol activities. Several genes appeared to be induced on P. parasitica hyphae and were found to be related with metabolism and regulation of gene expression. It is likely that the biocontrol strain took a metabolic advantage from the plant pathogenic fungus and then suppressed citrus root rot effectively. The result was parallel with those from the adaptation of IVET in P. fluorescens, a plant growth promoting rhizobacteria (PGPR). Interestingly, genes encoding components for type III secretion system have been identified as rhizosphere-induced genes in the PGPR strain. The type III secretion system may play a certain role during interaction with its counterpart plants. Application of IVET has been demonstrated in a wide range of bacteria. It is an important strategy to genetically understand complicated bacterial traits in the environment.

• Current Research on Agriculture and Life Sciences
• /
• 제23권
• /
• pp.33-41
• /
• 2005

멕시코와 네팔에서 도입된 고추 유전자원 50점과 대조품종 등을 포함한 총 130여점에 대하여 풋마름병과 역병에 대한 저항성을 검정하였다. 풋마름병에는 KC897, KC939, KC936가 KC126, KC350, KC351, KC353에 더하여 새로운 저항성 재료로 나타났다. 역병에는 저항성이 발견되지 않았다.

• 한국환경농학회지
• /
• 제25권3호
• /
• pp.228-235
• /
• 2006

Pseudomonas aeruginosa $GRC_2$, siderophore-producing strain, inhibited growth of Macrophomina phaseolina in vitro and reduced charcoal rot in seeds of Brassica juncea in field when coated with adaptive strains. P. aeruginosa $GRC_2$ and Azotobacter chroococcum $AC_1$ produced indole-3-acetic acid and solubilized insoluble phosphate. A. chroococcum $AC_1$ fixed nitrogen asymbiotically. Urea and diammonium phosphateadaptive variant strains of P. aeruginosa and A. chroococcum strongly inhibited M. phaseolina in comparison to parental strains. Bacterization of seeds induced seed germination, seedling growth, and enhanced yield of B. juncea by 10.87% as compared to full doses of urea and diammonium phosphate. Both adaptive strains of chemical fertilizers aggressively colonized roots, showing effectiveness to growth and developments of B. juncea.

• 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.

• 한국균학회지
• /
• 제49권4호
• /
• pp.441-454
• /
• 2021

Fungal diseases including anthracnose, stem rot, blight, wilting, and root rot of crops are caused by phytopathogens such as Colletotrichum species, Sclerotinia sclerotiorum, Phytophthora species, and Fusarium oxysporum and F. solani which threaten the production of chili pepper. In this study, to identify biological control agents (BCAs) of phytopathogenic fungi, potentially useful Bacillus species were isolated from the field soils. We screened out five Bacillus strains with antagonistic capacity that are efficiently inhibiting the growth of phytopathogenic fungi. Bacillus species were characterized by the production of extracellular enzymes, siderophores, and indole-3-acetic acid (IAA). Furthermore, the influence of bacterial strains on the plant growth promoting activity and seedling vigor index were assessed using Brassica juncea as a model plant. Inoculation with Bacillus subtilis SRCM 121379 significantly increased the length of B. juncea shoots and roots by 45.6% and 52.0%, respectively. Among the bacterial isolates, Bacillus subtilis SRCM 121379 showed the superior enzyme activities, antagonistic capacity and plant growth promoting effects. Based on the experimental results, Bacillus subtilis SRCM 121379 (GenBank accession no. NR027552) was finally selected as a BCA candidate.

• 한국약용작물학회지
• /
• 제9권3호
• /
• pp.211-219
• /
• 2001

1999년과 2000년 수원 작물시험장 백출 시험재배포장에서 시기별 P. drechsleri에 의한 역병 이병주율을 조사한 결과 파종 후 약 30-45일의 유묘기와 하절기 장마 이후 두 시기에 크게 증가하였다. 유묘기의 역병 발생은 20일간 $15^{\circ}C$ 이상의 평균 기온과 100mm이상의 강우 조건하에서 발생하며, 하절기 장마로 인한 토양 과습 조건에서 다시 증가하는 비슷한 경향을 보였다. 역병 이병주율은 종근 이식재배가 56.0%로 종자파종재배 18.6%보다 역병발생의 피해가 큰 것으로 나타났다. 재배조건 및 포장조건이 다른 5개 포장의 역병 이병주율과 토양내 역병 균밀도를 조사한 결과 객토포장이 연작포장에 비해, 무피복포장이 피복포장에 비해 역병 발생에 의한 피해가 적었으며, 역병 이병주의 확산은 재배방법 및 포장조건에 따라 다르나 토양 내 역병 원인균인 P. drechsleri의 균밀도와 깊은 연관이 있는 것으로 보인다. 종근 파종 후 각각 재배 2년 차와 재배 3년 차인 안동 북부 시험장과 영주 개인농가의 백출 포장의 토양내 역병 균밀도는 수원 작물시험장 백출 재배포장에 비해 비교적 낮았으나, 역병 발생에 의한 피해가 큰 것으로 나타나 백출 재배 시 2년 이상의 연작은 적합치 않은 것으로 나타났다.

• Journal of Ginseng Research
• /
• 제30권2호
• /
• pp.78-81
• /
• 2006

Freshly harvested, immature (green) seeds of North American ginseng (Panax quinquefolius L.) were stratified for up to 3 years in plastic pails in controlled environment rooms at $5{\pm}1^{\circ}C$ for 9 months and then $21{\pm}2^{\circ}C$ for 3 months (Trt. 1, regular stratification), or continuously at $-2{\pm}0.2^{\circ}C$ (Trt. 2), or continuously at $3{\pm}0.2^{\circ}C$ (Trt. 3). During stratification at -2 and $3^{\circ}C$ embryos did not grow. On seeding in the field embryos grew rapidly and resultant seedlings were comparable to those from regularly stratified seed. Seedling emergence rate was acceptable at the industry expected rate of 68% after one year of storage, but not after two years storage when it declined to 17.5%. Seed rot was so severe in year 3 that no planting was carried out. Seedling and second year growth were similar at the three stratification temperatures; most importantly, root dry weight (economic yield) was similar. Low-temperature storage of freshly-harvested North American ginseng seed is an acceptable method for short-term retention of propagating material.

• 한국식물병리학회지
• /
• 제13권3호
• /
• pp.152-159
• /
• 1997

병든 생강으로부터 분리한 6개 Pythium 균주들은 여러 가지 형태적, 생리적 특성에서 Pythium myriotylum Drechsler로 동정되었다. 이 균들은 생강 지하부의 싹, 근경, 뿌리, 땅가줄기 뿐만 아니라 지상부 잎, 줄기 전부분에 걸쳐 병원성이 강하였다. 이 균들은 오이, 수박 등 10개 작물 혹은 잡초의 어린 묘를 부패시켰으며 보리, 옥수수 등 공시한 3개 작물 유묘의 지상부 생장이나 뿌리 생장을 현저히 억제하였다. 이 균들의 생육 최고, 최적, 최저온도는 각각 39~45$^{\circ}C$, 33~37$^{\circ}C$, 5~7$^{\circ}C$였으며 생육최적 pH는 6~7이었다. 이 균들의 균사생장은 V-8 juice 배지에서 가장 빨랐으나 기중균사량은 PDA와 옥수수전즙배지에서 가장 많았다. 유주자낭과 장난기는 V-8 juice 배지에서 가장 잘 형성되었으며 유주자낭 형성 최적온도는 균주에 따라 20~35$^{\circ}C$, 장난기 형성은 15$^{\circ}C$의 저온에서 가장 양호하였다

• International Journal of Industrial Entomology and Biomaterials
• /
• 제31권2호
• /
• pp.107-114
• /
• 2015

Endophytes provide multifarious benefits such as promotion of plant growth and yield, suppression of phyto-pathogens, phosphate solubilising and fixation nitrogen. A study has been carried out to explore growth promotion and antifungal activities of endophytes of mulberry (Morus spp.). Endophytic bacteria were isolated from mulberry plants and studied their cultural, morphological characters, growth promotion as well as their antifungal activity against Rhizoctonia bataticola and Fusarium oxysporum , two mulberry root rot associated pathogens. Except two isolates, all bacteria were colourless and the colony size of eight isolates was small. The margin of five isolates was irregular and the consistency of three isolates was creamy, six isolates was slimy and one was mucoid. Texture of seven isolates was convex and others were flat. Eight isolates were gram positive and the rest Gram negative, five were cocci and others were bacilli (rod shaped). Four isolates were motile and all were catalase positive and only three isolates were oxidase positive. Spore staining was positive only for two isolates. The growth promotion study showed that there was significant difference in root length and seedling length. The antagonistic effect of the bacterial isolates was tested against R. bataticola showed significant (p <0.05) influence of the bacteria, days after inoculation and their interaction on the inhibition of fungal growth. The isolate En-7 completely inhibited the fungus followed by En-5 (66.67%). The bacterial isolates significantly (p <0.05) inhibited growth of F. oxysporum in PDA. The mean inhibition was higher (70.45%) in case of En-7 followed by En-8 (68.65%) and En-10 (66.44%). The study reveals that some endophytic bacteria associated with mulberry have growth promotion and antifungal activity and could be explored for promotion of mulberry growth and managing root rot disease.

• The Plant Pathology Journal
• /
• 제32권5호
• /
• pp.396-406
• /
• 2016

Continuous supplementation of mineral nutrients and salicylic acid (SA) as foliar application could improve efficacy in controlling basal stem rot (BSR) disease in oil palm seedling. It is revealed from the results that the highest disease severity index (58.3%) was recorded in T8 treatments at 9 months after inoculation. The best disease control was achieved by T7 treatments (calcium/copper/SA [Ca/Cu/SA]) (5.0%) followed by T1 (5.5%), T5 (5.8%), T3 (8.3%), T6 (8.3%), T4 (13.3%), and T2 (15.8%) treatments. Continuous supplementation of Ca/Cu/SA was found to be the most effective in controlling the disease and the high performance liquid chromatography results showed the detection of ergosterol at very low concentration in the treated samples. Moreover, the transmission electron microscopy analysis results clearly indicated that T7 treatment was also enhancing lignification, which was responsible for the thickness of the secondary cell walls and middle lamella compared to untreated samples. It was therefore, concluded that continuous supplementation of minerals nutrients and SA could effectively suppress disease severity by reducing ergosterol activity and also improve the process of lignification in the treated plants. Furthermore, this treatment also managed to delay the onset of BSR symptoms and promote the growth of the seedlings and eventually suppress the BSR disease.