• Korean Journal of Medicinal Crop Science
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• v.12 no.6
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• pp.473-477
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• 2004

Wasabis (Wasabia japonica Matsum.) have been used as a spice with its petioles and rhizomes, but the production of its rhizomes in upland cultivation was very difficult for the severe damage of rotting disease during summer season. This experiment was carried out to increase the yield of marketable rhizome in wasabi when cultured in upland. Seedlings were raised in sub-alpine area for 7 and 12 months and then transplanted to experimental area on Sept. 20 and the yield was investigated on May 12 of the next year. The marketable rhizome(above 40g/plant) was produced in seedlings raised for 7 months. Production rate of marketable rhizome was 13.3% and total yield was 72.9 kg/10a. The content of allylisothiocyanate in rhizome of upland wasabi was 0.777 mg/g and its content was equal to wasabi cultured in water condition for 18 months. These results suggested that the upland cultivation of wasabi seedlings raised in sub-alpine area for 7 months was possible to product marketable rhizome.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.107-114
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• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.393-400
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• 2016

Fusarium graminearum is the main cause of substantial economic loss in wheat production. The aim of this study is to investigate biocontrol potential of Lysobacter antibioticus HS124 against F. graminearum and to purify an antifungal compound. In preliminary study, n-butanol crude extract revealed destructive alterations in the hyphal morphology of F. graminearum and almost degraded with $1,000{\mu}g\;mL^{-1}$ concentration. For further study, the antifungal compound extracted from the n-butanol crude extract of L. antibioticus HS124 was identified as N-Butyl-tetrahydro-5-oxofuran-2-carboxamide ($C_9H_{16}NO_3$) using NMR ($^1H-NMR$, $^{13}C-NMR$, $^1H-^1H\;COSY$, HMBC, and HMQC), and HR-ESI-MS analysis. To our knowledge, N-Butyl-tetrahydro-5-oxofuran-2-carboxamide may be a novel compound with molecular weight of 186.1130. The minimum inhibitory concentration value of antifungal compound was $62.5{\mu}g\;mL^{-1}$ against F. graminearum. In an in vivo pot experiment, crown rot disease from F. graminearum was inhibited when wheat seeds were treated with both HS124 culture and F. graminearum. Growth of wheat seedling was enhanced by treatment of HS124 compared to control. Our results suggest that L. antibioticus HS124 characterized in this study could be successfully used to control F. graminearum and could be used as an alternative to chemical fungicides in modern agriculture.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.67-73
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• 2008

Seedling damping-off and bottom rot caused by Rhizoctonia solani are yield limiting diseases of crisphead lettuce. To provide biocontrol measure in the management of the diseases, biocontrol strain Pseudomonas aeruginosa LY-11 was isolated from lettuce rhizosphere and introduced into crisphead lettuce rhizosphere by the seed coating delivery method. Alginate was used as a coating material to generate beads containing $10^6-10^{6.5}$ colony-forming units (CFUs) of viable bacterial cells of LY-11. When seeds germinated from the alginate beads containing the strain LY-11, the bacteria established mostly in plant rhizosphere to maintain at least $10^4$ CFU per gram of plant tissues. Crisphead lettuce seedlings germinated from the entrapped seeds were less affected from damping-off and bottom rot with disease control values of 70.4% and 85.4% respectively. Although P. aeruginosa LY-11 colonized plant rhizosphere and not phyllosphere, the result indicated that bottom rot caused by the foliar inoculation of R. solani was effectively reduced by the rhizobacteria. All data suggested that immobilized rhizobacterial application in seeds by alginate coating could control damping-off and induce induced systemic resistance of crisphead lettuce to reduce bottom rot.

• The Plant Pathology Journal
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• v.33 no.3
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• pp.229-237
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• 2017

Rye (Secale cereale L.) serves as an alternative host of Pyrenophora tritici-repentis (PTR) the cause of tan spot on wheat. Rye is cultivated as a forage or cover crop and overlaps with a significant portion of wheat acreage in the U.S. northern Great Plains; however, it is not known whether the rye crop influences the evolution of PTR races. We evaluated a global collection of 211 rye accessions against tan spot and assessed the diversity in PTR population on rye in South Dakota. All the rye genotypes were inoculated with PTR races 1 and 5, and infiltrated with Ptr ToxA and Ptr ToxB, at seedling stage. We observed 21% of the genotypes exhibited susceptibility to race 1, whereas, 39% were susceptible to race 5. All 211 accessions were insensitive to both the Ptr toxins. It indicates that though rye exhibits diversity in reaction to tan spot, it lacks Ptr ToxA and ToxB sensitivity genes. This suggests that unknown toxins or other factors can lead to PTR establishment in rye. We characterized the race structure of 103 PTR isolates recovered from rye in South Dakota. Only 22% of the isolates amplified Ptr ToxA gene and were identified as race 1 based on their phenotypic reaction on the differential set. The remaining 80 isolates were noted to be race 4. Our results show that races 1 and 4 are prevalent on rye in South Dakota with a higher frequency of race 4, suggesting a minimal role of rye in the disease epidemiology.

• Journal of Plant Biotechnology
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• v.43 no.1
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• pp.99-103
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• 2016

In perennial ginseng plantations, the effective control of various diseases is one of the most critical factors for increasing yields. Enhancing the resistance to disease through induced systemic resistance (ISR) and anti-microbial activity of beneficial soil bacteria, is currently considered to be a potential promising approach to integrate pathogen management for sustainable agriculture. However, the effective in vitro culture systems for testing ISR in ginseng plants have been rarely reported. In this study, I have successfully developed an in vitro germ-free culture system of Panax ginseng seedling for diverse purposes. With this useful system, we also tested BTH-induced priming effects against Botrytis cinerea and Colletotrichum panacicola. Compared to the drain method for enhancing ISR effects to ginseng seedlings, the direct method of spraying leaves somewhat increased the defense activity to these major fungal pathogens. Consistently, the expression of pathogen related PgPR10 and PgCAT were greatly and rapidly enhanced in the BTH-treated ginseng seedlings by treatment with C. panacicola. Our results revealed that the in vitro culture system can be used for developing eco-friendly and versatile bio-control agents for harmful diseases in ginseng cultivation.

• Mycobiology
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• v.39 no.3
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• pp.206-218
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• 2011

The seed-borne mycoflora of sorghum and foxtail millet collected from different growing areas in South Korea were isolated and taxonomically identified using dry inspection, standard blotter and the agar plate method. We investigated the in vitro and in vitro germination rates of disinfected and non-disinfected seeds of sorghum and foxtail millet using sterilized and unsterilized soil. The percent recovery of seed-borne mycoflora from the seed components of sorghum and foxtail millet seeds was determined and an infection experiment using the dominant species was evaluated for seedling emergence and mortality. A higher number of seed-borne fungi was observed in sorghum compared to that of foxtail millet. Eighteen fungal genera with 34 fungal species were identified from the seeds of sorghum and 13 genera with 22 species were identified from the seeds of foxtail millet. Five dominant species such as Alternaria alternata, Aspergillus flavus, Curvularia lunata, Fusarium moniliforme and Phoma sp. were recorded as seed-borne mycoflora in sorghum and 4 dominant species (Alternaria alternata, Aspergillus flavus, Curvularia lunata, Fusarium moniliforme) were observed in foxtail millet. The in vitro and in vitro germination rates were higher using disinfected seeds and sterilized soil. More seed-borne fungi were recovered from the pericarp compared to the endosperm and seed embryo. The percent recovery of seed-borne fungi ranged from 2.22% to 60.0%, and Alternaria alternata, Curvularia lunata and 4 species of Fusarium were isolated from the endosperm and embryo of sorghum and foxtail millet. Inoculation of the dominant seed-borne fungi showed considerable mortality of seedlings. All the transmitted seed-borne fungi might well be a primary source of infection of sorghum and foxtail millet crops.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.171-176
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• 2009

Hydroponic culture has been developed to control soilborn diseases, to increase yield and to enhance the quality of vegetable, The pathogen could be detected from infected plant materials, hydroponic tanks, culture solution and solid media of the severely infected greenhouse, The density of pathogen population was coincided with the severity of disease incidence, For example, 1,900cfu m$L^{-1}$ pf pathogens were counted from tomato plants sampled in a 20% diseased greenhouse. The pathogens may be introduced in the greenhouse through the contaminated soil surrounding the house and/or through the infected young seedlings grown on the nursery soil. Also, not detected to Ralstonia solanacearum from tomato seeds (House Momotaro, Bbaebbae, Ggoggo, and Minicarol cultivar) selling at a market.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.244-254
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• 2020

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.684-694
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• 2018

This study describes the successful establishment of a cryopreservation protocol for Citrus limon cultivars: 'Frost Eureka limon' and 'Cook Eureka limon', using a droplet-vitrification method. The shoot tips that were excised from in vitro grown seedlings of the two cultivars were preserved in liquid nitrogen (LN) and successfully regenerated into whole plants. Excised shoot tips were pre-cultured for 1 or 2 days in 0.3 M and 0.5 M sucrose solutions at $25^{\circ}C$ and incubated in a loading solution (LS) composed of 17.5% glycerol + 17.5% sucrose in Murashige and Skoog (MS) medium for 40 min at $25^{\circ}C$. Prior to direct immersion in LN for 1 h, the shoot tips were dehydrated with plant vitrification solution 2 (PVS2) at $0^{\circ}C$ or PVS3 at $25^{\circ}C$. The frozen shoot tips were re-warmed and unloaded with 1.2 M sucrose in $\text\tiny{^1/_2}$ MS for 30 min at $25^{\circ}C$. Shoot tips were post-cultured overnight on survival medium and then micrografted onto 'trifoliate orange' (Poncirus trifoliate (L.) Raf. seedling rootstocks for recovery and to produce whole plants. The highest regrowth rates were 53.5% and 50.3% for cryopreserved shoot tips of 'Frost Eureka limon' and 'Cook Eureka limon', respectively, when pre-cultured in 0.3 M and 0.5 M sucrose concentrations in a sequencing manner, with LS and treated with PVS2 for 60 min at $0^{\circ}C$. We also investigated whether the ammonium ion concentration on post-culture medium affected the viability of the cryopreserved Citrus shoot tips. The viability of cooled samples, following culturing on woody plant media (WPM) containing $\text\tiny{^1/_4}$ ammonium nitrate overnight before micrografting, was the highest (70.3%) in 'Frost Eureka limon'. The study described here is a cost-effective and safe method to conserve Citrus fruit cultivars, for the improvement and large-scale multiplication of fruit plants and for breeding disease resistance.