• Research in Plant Disease
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• v.30 no.2
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• pp.181-188
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• 2024

Southern blight, caused by the soil-borne fungus Sclerotium rolfsii, is a serious disease that affects many economically important crops. In this study, we selected Bacillus subtilis GJ6-14, from a total of 260 strains, to control Southern blight in pepper plants. In both seedling and plant tests, GJ6-14 significantly suppressed disease incidence and severity compared to control, furthermore, GJ6-14 demonstrated efficient colonization in the rhizosphere by maintaining the population from log 5.41 to log 3.92 in the pathogen-inoculated plants, indicating its potential as a biocontrol agent. Molecular analysis revealed up-regulation of defense-related genes, such as a 7.6-fold increase in LOX1 and 15.5-fold increase in PR1, at 72 hr after inoculation of S. rolfsii in GJ6-14-treated plants, suggesting activation of plant defense mechanisms. Overall, our findings highlight the promising role of B. subtilis GJ6-14 as a potential biocontrol agent in sustainable management of Southern blight in pepper plants.

• The Plant Pathology Journal
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• v.33 no.3
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• pp.264-275
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• 2017

The spent mushroom substrate (SMS) of Lentinula edodes that was derived from sawdust bag cultivation was used as materials for controlling Phytophthora blight disease of pepper. Water extract from SMS (WESMS) of L. edodes inhibited mycelial growth of Phytophthora capsici, suppressed Phytophthora blight disease of pepper seedlings by 65% and promoted growth of the plant over 30%. In high performance liquid chromatography (HPLC) analysis, oxalic acid was detected as the main organic acid compound in WESMS and inhibited the fungal mycelium at a minimum concentration of 200 mg/l. In quantitative real-time PCR, the transcriptional expression of CaBPR1 (PR protein 1), CaBGLU (${\beta}$-1,3-glucanase), CaPR-4 (PR protein 4), and CaPR-10 (PR protein 10) were significantly enhanced on WESMS and DL-${\beta}$-aminobutyric acid (BABA) treated pepper leaves. In addition, the salicylic acid content was also increased 4 to 6 folds in the WESMS and BABA treated pepper leaves compared to water treated leaf sample. These findings suggest that WESMS of L. edodes suppress Phytophthora blight disease of pepper through multiple effects including antifungal activity, plant growth promotion, and defense gene induction.

• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.319-324
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• 1998

Induction of systemic acquired resistance (SAR) against phytophthora blight and pathogenesis-related (PR) protein accumulation by TMV infection in pepper plant (Capsicum annuum cv. Nockwang) were examined to understand the mechanism of the systemic acquired resistance in pepper plant. The zoospore suspension of Phytophthora capsici was inoculated on stem of pepper plant in which TMV-pepper strain had been inoculated on fully expanded upper leaves, and thephytopha blight incidence was examined. Both disease severity and lesion length of phytophthora blight were much smaller in TMV pre-inoculated pepper plant than in uninoculated control plants. The phytophthora blight incidence was decreased about 50% in the TMV pre-inoculated pepper, compared to the uninoculated control plant at 10 days after P. capsici inoculation. Accumulation of PR1 and PR5 proteins in intercellular fluid of TMV-inoculated and uninoculated upper leaves were monitored by immuno-blot with tobacco P1b and PR5a, antibody during induction of SAR. PR1 and PR5 were detected from 24 hours after TMV inoculation in both TMV-inoculated and uninouclated upper leaves, and increased rapidly in TMV-inoculation in uninoculated upper leaves were defoliated. PR5 could be detected upto 20 days after TMV inoculation in uninoculated upper leaves. These results suggest that TMV infection induces SAR against phytophthora blight in pepper plant, and that PR proteins are accumulated very rapidly during induction of SAR and maintained for quite long time in pepper plant.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.172-184
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• 2012

An infection risk model for Phytophthora blight on chili pepper was developed to estimate the first date of disease occurrence in the field. The model consisted of three parts including estimation of zoosporangium formation, soil water content, and amount of active inoculum in soil. Daily weather data on air temperature, relative humidity and rainfall, and the soil texture data of local areas were used to estimate infection risk level that was quantified as the accumulated amount of active inoculum during the prior three days. Based on the analysis on 190 sets of weather and disease data, it was found that the threshold infection risk of 224 could be an appropriate criterion for determining the primary infection date. The 95% confidence interval for the difference between the estimated date of primary infection and the observed date of first disease occurrence was $8{\pm}3$ days. In the model validation tests, the observed dates of first disease occurrence were within the 95% confidence intervals of the estimated dates in the five out of six cases. The sensitivity analyses suggested that the model was more responsive to temperature and soil texture than relative humidity, rainfall, and transplanting date. The infection risk model could be implemented in practice to control Phytophthora blight in chili pepper fields.

• The Plant Pathology Journal
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• v.15 no.6
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• pp.319-322
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• 1999

In order to obtain bacterial metabolites inducing disease resistance in pepper plant, two hundred bacterial isolates were isolated from the rhizosphere soil of tobacco, cucumber, and pepper plant. Ethyl acetate extract of each bacterial culture was used to screening for induction of resistance against phytophthora blight of pepper plant. Application of ethyl acetate extract of an isolate SH122 culture to pepper plant conferred resistance against phytophthora blight consistently and significantly. According to cellular fatty acid analysis and other characteristics, the SH122 culture were significantly lower than those on control plants treated with ethyl acetate extract of nutrient broth. The B. pumilus SH122 itself of ethyl acetate extract of its culture did not show antifungal activity against phytophthora blight in pepper plants.

• Research in Plant Disease
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• v.19 no.3
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• pp.208-215
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• 2013

3-(4-Hydroxyphenyl)-propionic acid (HPP) is a bacterial metabolite synthesized and released by an entomopathogenic bacterium Xenorhabdus nematophila K1. In this study, the control efficacy of HPP was tested against Phytophthora blight and anthracnose of red pepper plants. HPP suppressed mycelial growth of Phytophthora blight and anthracnose pathogens. Under natural sunlight condition, HPP maintained the antifungal activity on the diseases for at least twenty five days. The antifungal activity was not decreased even in the condition of soil-water. It was proved that HPP was able to penetrate the roots and travel upward of the red pepper plants. When HPP suspension was applied to soil rhizosphere before transplanting the red pepper seedlings or was regularly sprayed to the foliage of the plants with ten days interval, it resulted in significant reduction of the disease occurrences (Phytophthora blight and anthracnose) without any phytotoxicity. These results suggested that HPP can be developed to a systemic agrochemical against Phytophthora blight and anthracnose of red pepper plants.

• Horticultural Science & Technology
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• v.28 no.5
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• pp.802-809
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• 2010

Phytophthora blight of pepper is the most economically important disease in the world cultivation regions. We investigated the phytophthora blight resistance of 300 accessions of Korean landrace of hot pepper germplasms collected from 83 local regions. The disease incidence rate was checked from 7 days to 28 days at an interval of 7 days after inoculation under greenhouse conditions. Among 300 accessions, the disease incidence rate of phytophthora blight of 67 accessions of pepper germplasm was more than 60.1%, while no disease was observed in 37 accessions at 7 days after inoculation. At 28 days after inoculation, five and eleven accessions of pepper germplasm were resistance and moderate resistance to $P.$ $capsici$, respectively. Two hundred forty four susceptible accessions (81.3%) of pepper were scored as having more than 60.1% of disease incidence of phytophthora blight. This result suggests that five candidate pepper germplasm might be used as breeding resources for the phytophthora blight resistance breeding program. Also, further genetic studies should be carried out to verify this result, with the overall focus of providing information on important characteristics of pepper germplasm.

• Research in Plant Disease
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• v.16 no.1
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• pp.41-47
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• 2010

A total of 10,753 oligotrophic bacteria were isolated from the cultivated soils of red-pepper infected by Phytophthora blight disease in various regions of Korea (Chungju, Anmyon, Taean, Andong, Eumsung and Goesan). Seven bacteria isolates among these collected resources were selected by the first screening of in vitro antagonistic assay against major several plant pathogenic fungi including Phytophthora capsici. Finally, strain 7F was selected by pot assay for a possible biological control agent against Phytophthora blight disease of pepper seedling in the greenhouse. Strain 7F was identified as Bacillus subtilis on the basis of its 16S rDNA sequence analysis and as standardized biochemical characteristics assay kits such as API20 NE. In the experiment of P. capsici zoospore infected red-pepper on the pot test, infection rate of red-pepper with nonetreatment to Phytophthora blight disease was 87%, while the rate was only 6% in the pot treated with strain 7F. This result indicated that the Bacillus subtilis strain 7F will be useful as a potential biocontrol agent for Phytophthora blight disease of red-pepper.

• Research in Plant Disease
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• v.17 no.1
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• pp.1-12
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• 2011

Incidence of Phytophthora blight of hot pepper (Capsicum annuum) and yield (fresh weight) of pepper fruits were investigated at four separate fields located in Cheongwon, Boeun, Eumsung, and Goesan, which are major pepper production areas in Chungcheongbuk-Do. In all of the experimental fields except the Goesan field, increased incidence of Phytophthora blight led to decreased yield of pepper fruits. The harvest time in which the yield of red pepper fruits was highly correlated with the incidence of Phytophthora blight was different between areas: it was highly correlated in the third harvest in Cheongwon (y=-11.0x+435.2, $r^2$=0.99), but in the second harvest in Boeun (y=-15.0x+944.6, $r^2$=0.76). In contrast, there was a very low correlation between the pepper yield and the disease incidence in Goesan in which pepper seedlings grafted on resistant stocks were planted. The final disease incidence in the Cheongwon experimental field reached 100% more than 40 days later in 2007 compared with that in 2006. The control threshold of Phytophthora blight in the pepper fields where disease incidence had been lower than 5% was set as 0.8% disease incidence, which caused less than 5% yield loss.

• Journal of Mushroom
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• v.13 no.1
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• pp.16-20
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• 2015

Water extracts from spent mushroom substrate (SMSE)of edible mushrooms, Pleurotus eryngii, Hericium erinaceus and Lentinula edodes promoted growth of pepper seedling. Mycellial growth rate of Phythopthora capsici and Fusarium oxysporum was dramatically inhibited by 100% and 70% on PDA added with SMSE of H. erinaceus. SMSEs from H. erinaceus, P. eryngii, and L. edodes effectively reduced the disease severity of Phytophthora blight of pepper caused by Phytophthora capsici to 75%, 10% and 35%, respectively. These results suggested that SMSE from the mushrooms have dual effects that suppress phythopthora blight disease and promote plant growth of pepper.