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Naing K.W.,Chonnam National University | Anees M.,Kohat University of Science and Technology | Nguyen X.H.,Chonnam National University | Lee Y.S.,Chonnam National University | And 4 more authors.
Journal of Phytopathology | Year: 2014

For field application of a bacterial strain used to control Phythophthora capsici, we will need a biologically and economically efficient carrier medium. The known antagonist Paenibacillus ehimensisKWN38 was grown in a grass medium where it showed high antifungal and lytic enzyme activities. To demonstrate the potential of P. ehimensisKWN38 for biocontrol of late blight disease in pepper, pot trials were conducted by treating the 1-month-old plants with water (W), a selected grass medium (G3), G plus P. ehimensisKWN38 inoculation (G3P) or synthetic fungicide (F). The shoot dry weight in G3P was higher than that in W and F treatments at 15 days after zoospore infection (DZI). The root dry weight in G3P was also higher than that in W. The root mortality of G3 and W increased over 58 and 80% at 15 DZI, and some plants in those treatments wilted due to the failure of root physiology. The plants in G3P and F survived well because of their better root health conditions. Soil cellulase activity of G3P was consistently higher than that of W and F at earlier observation times (0, 2 and 6 DZI). The root β-1,3-glucanase activity of G3P promptly increased to maximum shortly after zoospore infection and reached the maximum value of 51.12 unit g-1 of fresh weight at 2 DZI. All these results indicate that inoculation of P. ehimensisKWN38 to the root zone of potted pepper plants increases plant growth, root and soil enzyme activities and alleviates the root death caused by infection with P. capsici zoospores. © 2013 Blackwell Verlag GmbH. Source

Nguyen X.-H.,Chonnam National University | Naing K.-W.,Chonnam National University | Lee Y.-S.,Chonnam National University | Tindwa H.,Chonnam National University | And 6 more authors.
Plant Pathology Journal | Year: 2012

The root rot of pepper (Capsicum annuum L.) caused by Phytophthora capsici is one of the most important diseases affecting this crop worldwide. This work presents the evaluation of the capacity of Streptomyces griseus H7602 to protect pepper plants against Phytophthora capsici and establishes its role as a biocontrol agent. In this study, we isolated an actinomycete strain H7602 from rhizosphere soil, identified it as Streptomyces griseus by 16S rRNA analysis and demonstrated its antifungal activity against various plant pathogens including P. capsici. H7602 produced lytic emzymes such as chitinase, β-1,3-glucanase, lipase and protease. In addition, crude extract from H7602 also exhibited destructive activity toward P. capsici hyphae. In the pot trial, results showed the protective effect of H7602 against pepper from P. capsici. Application of H7602 culture suspension reduced 47.35% of root mortality and enhanced growth of pepper plants for 56.37% in fresh root and 17.56% g in fresh shoot as compared to control, resulting in greater protection to pepper plants against P. capsici infestation. Additionally, the enzymatic activities, chitinase and β- 1,3-glucanase, were higher in rhizosphere soil and roots of pepper plants treated with H7602 than other treated plants. Therefore, our results indicated a clear potential of S. griseus H7602 to be used for biocontrol of root rot disease caused by P. capsici in pepper. ©The Korean Society of Plant Pathology. Source

Jeon S.W.,Corporation of Nature and People | Naing K.W.,Chonnam National University | Lee Y.S.,Chonnam National University | Nguyen X.H.,Chonnam National University | And 2 more authors.
Horticulture Environment and Biotechnology | Year: 2015

Brown patch disease, caused by Rhizoctonia solani, is one of the most serious diseases of turf grasses including bentgrass (Agrostis palustris). This disease is usually controlled by different formulations of synthetic fungicides. In this study, two pot trials were carried out to investigate the biocontrol potential of the antagonistic strain Paenibacillus ehimensis KWN38 against R. solani, and to examine the growth response of bentgrass to the inoculated strain. Bentgrass mats with root system in plastic boxes were treated with winter grass medium (W), W plus P. ehimensis KWN38 inoculation (WP), summer grass medium (S), S plus P. ehimensis KWN38 inoculation (SP), fertilizer (F), and F plus fungicide (FF) once every 10 days for three months. After the first month, all pots were infected with R. solani. Sixty days after infection, the leaves of bentgrass in all control treatments (W, S, and F) showed high levels of infection, with significantly higher values than those of WP, SP and FF. The leaf fresh and dry weights of bentgrass innoculated with P. ehimensis KWN38 were all greater than the control treatments W, S and F. Similarly, both fresh and dry weights of the roots and the chlorophyll contents of bentgrass in WP and SP were significantly higher than those of W, S, F and FF. Moreover, bentgrass innoculated with P. ehimensis KWN38 grew faster and showed greater growth performance as compared to the other treatments in the second pot trial with infected bentgrass. A butanol extract of the P. ehinmensis KWN38 culture supernatant significantly reduced the number of fungal colonies initiating from sclerotial fragments on potato dextrose agar. The growth of monilioid cells of R. solani was delayed by treatment with P. ehimensis KWN38 culture broth, while they elongated earlier into thinner structures in the control treatment. In conclusion, the antagonist P. ehimensis KWN38 can be considered as an effective biocontrol agent against brown patch disease, as well as a promising plant growth promoting bacteria of bentgrass. © 2015, Korean Society for Horticultural Science and Springer-Verlag GmbH. Source

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