• Journal of Microbiology and Biotechnology
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• 제27권10호
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• pp.1763-1772
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• 2017

This study aimed to isolate and characterize antibacterial metabolites from Pharbitis nil seeds and investigate their antibacterial activity against various plant pathogenic bacteria. The methanol extract of P. nil seeds showed the strongest activity against Xanthomonas arboricola pv. pruni (Xap) with a minimum inhibition concentration (MIC) value of $250{\mu}g/ml$. Among the three solvent layers obtained from the methanol extract of P. nil seeds, only the butanol layer displayed the activity with an MIC value of $125{\mu}g/ml$ against Xap. An antibacterial fraction was obtained from P. nil seeds by repeated column chromatography and identified as pharbitin, a crude resin glycoside, by instrumental analysis. The antibacterial activity of pharbitin was tested in vitro against 14 phytopathogenic bacteria, and it was found to inhibit Ralstonia solanacearum and four Xanthomonas species. The minimum inhibitory concentration values against the five bacteria were $125-500{\mu}g/ml$ for the n-butanol layer and $31.25-125{\mu}g/ml$ for pharbitin. In a detached peach leaf assay, it effectively suppressed the development of bacterial leaf spot, with a control value of 87.5% at $500{\mu}g/ml$. In addition, pharbitin strongly reduced the development of bacterial wilt on tomato seedlings by 97.4% at $250{\mu}g/ml$, 7 days after inoculation. These findings suggest that the crude extract of P. nil seeds can be used as an alternative biopesticide for the control of plant diseases caused by R. solanacearum and Xanthomonas spp. This is the first report on the antibacterial activity of pharbitin against phytopathogenic bacteria.

• Current Research on Agriculture and Life Sciences
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• 제18권
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• pp.9-17
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• 2000

풋마름병과 역병에 복합저항성인 계통을 육성하기 위한 노력으로서 앞서 역병 저항성으로 육성한 계통(16-2-3-2 = 역병 저항성 '칼미초', 19-1-3-7-1-1, 19-2-4-5-3-2 = 역병 저항성 '수비초', 김 등, 1996)과 풋마름병 저항성 계통(KC350 = MC 4, KC353 = PBC631)을 교배하여 육성한 $F_5$와 $BC_1F_4$, $F_6$와 $BC_1F_5$ 세대에 대해 1999년과 2000년에 각각 풋마름병과 역병에 대한 복합저항성을 검정하였다. 풋마름병과 역병에 복합 저항성을 보인 개체를 선발하여 다음 세대의 종자를 채종하였다.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.791-807
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• 2017

The type II secretion system (T2SS), which transports selected periplasmic proteins across the outer membrane, has rarely been studied in nonpathogens or in organisms classified as Betaproteobacteria. Therefore, we studied Cupriavidus metallidurans (Cme), a facultative chemilithoautotroph. Gel analysis of extracellular proteins revealed no remarkable differences between the wild type and the T2SS mutants. However, enzyme assays revealed that native extracellular alkaline phosphatase is a T2SS substrate, because activity was 10-fold greater for the wild type than a T2SS mutant. In Cme engineered to produce three Ralstonia solanacearum (Rso) exoenzymes, at least 95% of their total activities were extracellular, but unexpectedly high percentages of these exoenzymes remained extracellular in T2SS mutants cultured in rich broth. These conditions appear to permit an alternative secretion process, because neither cell lysis nor periplasmic leakage was observed when Cme produced a Pectobacterium carotovorum exoenzyme, and wild-type Cme cultured in minimal medium secreted 98% of Rso polygalacturonase, but 92% of this exoenzyme remained intracellular in T2SS mutants. We concluded that Cme has a functional T2SS despite lacking any abundant native T2SS substrates. The efficient secretion of three foreign exoenzymes by Cme is remarkable, but so too is the indication of an alternative secretion process in rich culture conditions. When not transiting the T2SS, we suggest that Rso exoenzymes are probably selectively packaged into outer membrane vesicles. Phylogenetic analysis of T2SS proteins supports the existence of at least three T2SS subfamilies, and we propose that Cme, as a representative of the Betaproteobacteria, could become a new useful model system for studying T2SS substrate specificity.

• The Plant Pathology Journal
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• 제25권3호
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• pp.263-269
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• 2009

Bacterial wilt, Fusarium wilt and Foot rot caused by Ralstonia solanacearum, Fusarium oxysporum, and Phytophthora capsici respectively, continue to be severe problems to tomato, potato and black pepper growers in Vietnam. Three bio-products, Bacillus vallismortis EXTN-1 (EXTN-1), Bacillus sp. and Paenibacillus sp. (ESSC) and Bacillus substilis (MFMF) were examined in greenhouse bioassay for the ability to reduce bacterial wilt, fusarium wilt and foot rot disease severity. While these bio-products significantly reduced disease severities, EXTN-1 was the most effective, providing a mean level of disease reduction 80.0 to 90.0% against bacterial wilt, fusarium wilt and foot rot diseases under greenhouse conditions. ESSC and MFMF also significantly reduced fusarium wilt, bacterial wilt and foot rot severity under greenhouse conditions. Bio-product, EXTN-1 with the greatest efficacy under greenhouse condition was tested for the ability to reduce bacterial wilt, fusarium wilt and foot rot under field condition at Song Phuong and Thuong Tin locations in Ha Tay province, Vietnam. Under field condition, EXTN-1 provided a mean level of disease reduction more than 45.0% against all three diseases compared to water treated control. Besides, EXTN-1 treatment increased the yield in tomato fruits 17.3% than water treated control plants.

• The Plant Pathology Journal
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• 제25권4호
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• pp.352-360
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• 2009

The potential of three plants extracts, to protect potato plants against bacterial wilt caused by Ralstonia solanacearum was determined under greenhouse and field conditions. All soil drenching treatments of aqueous plant extracts of Hibsicus sabdariffa, Punica granatum and Eucalyptus globulus significantly reduced the disease severity compared with inoculated control. Although the applications of all three plant extracts resulted in similar reductions of disease severity in field up 63.23 to 68.39%, treatment of E. globulus leaf extract was found greater in restricting the symptom development than other the two plant extracts in the greenhouse. More than 94% reduction in the bacterial wilt symptom was observed in potato plants. All tested plant extracts were effective in inhibiting the growth of bacterial pathogen, not only in vitro, but also in stem of potato plants as compared with the inoculated control Potato plants treated with extract of H. sabdariffa reduced bacterial growth more effectively than treatment with P. granatum and E. globulus. Activity of defence-related enzymes, including peroxidase, polyphenoloxidase and phenylalanine ammonia lyase, were significantly increased in plants treated with the plant extracts compared to the control during the experimental period. In general, the higher enzymes activities were determined in both inoculated and non-inoculated treated potato plants after 8 days from plant extracts treatment. These results suggested that these plant extracts may be play an important role in controlling the potato bacterial wilt disease, through they have antimicrobial activity and induction of systemic resistance in potato plants.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.12-12
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• 2017

Genetic improvement in potato can be carried out through several approaches, as sexual crosses, somatic hybridization, mutation and genetic engineering. Although the approach is different, but the goal is the same, to get a superior cultivar. Mutation and genetic engineering are very interesting methods for genetic improvement of potato plants. Mutation by gamma-ray irradiation have been performed to get some new potato cultivars which are more resistant to disease and have higher productivity. We have carried out a mutation of some potato cultivars and obtained some excellent clones to be potentially released as new superior cultivars. By the mutation method, we have released one potato cultivar for the French fries industry, and we registered one cultivar of potato for chips, and two cultivar for vegetable potatoes. Actually we are doing multi-location trial for three clones to be released as new cultivars. Through genetic engineering, several genes have been introduced into the potato plant, and we obtained several clones of transgenic potato plants. Transgenic potato plants containing FBPase gene encoding for fructose bisphosphatase, have a higher rate of photosynthesis and higher tuber productivity than non-transgenic plants. This result suggests that FBPase plays an important role in increasing the rate of photosynthesis and potato tuber productivity. Some transgenic potatoes containing the Hd3a gene are currently being evaluated for their productivity. Over expression of the Hd3a gene is expected to increase tuber productivity and induce flowering in potatoes. Transgenic potato plants containing MmPMA gene encoding for plasma membrane ATPse are more tolerant to low pH than non-transgenic plants, indicating that plasma membrane ATPase plays an important role in the potato plant tolerance to low pH stress. Transgenic potato plants containing c-lysozyme genes, are highly tolerant of bacterial wilt diseases caused by Ralstonia solanacearum and bacterial soft rot disease caused by Pectobacterium carotovorum. Expression of c-lyzozyme gene plays an important role in increasing the resistance of potato plants to bacterial diseases.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2005년도 추계학술대회 및 한일 식물생명공학 심포지엄
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• pp.106-111
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• 2005

For breeding of a new rootstock for eggplant production, somatic hybrids between two species, Solanum integrifolium and S. sanitwongsei were obtained through protoplast fusion. The former species has been commonly used for rootstock for eggplant production in Japan. Eggplants on these rootstocks are more productive than ungrafted plants, but are susceptible to bacterial wilt caused Ralstonia solanacearum. While the latter species is resistant, the growth of eggplants on this rootstock is rather slow and low yield. Protoplast of both species were isolated from cotyledons, and inactivated with iodoacetamide or UV-irradiation, then fused electrically. The fused products were then cultured. Regenerated plantlets were then transplanted on soil then maintained in a green house. The plants were classified into four groups. Those in the first group showed morphological characters intermediate of the parentalspecies. The plants bore fruit with viable seeds. The plants showed a chromosome number of 2n=48, the sum of those of the parental species, and are suggested to be symmetric fusion products. While plants in the other groupswas less vigorous and showed chromosome number 2n= 68 to 72 suggesting asymmetric fusion products by genomic in situ hybridization(GISH). Isozyme pattern of shikimate dehydrogenase (SKDH; EC 1.1.1.25), isocitrate dehydrogenase (IDH; EC 1.1.1.41) and phosphoglucomutase (PGM; EC 2.7.5.1) showed that 24 regenerated plants in three groups were somatic hybrids. Analysis of random amplified polymorphic DNA (RAPD) showed that 43 S. integrifolium-specific and 57 S. sanitwongsei-specific bands were all found in 24 plants. Both somatic hybrids and its S1 plants were found to be resistant to bacterial wilt, and eggplant grafted these plants using for rootstocks were more productive than grafted mother plants. Now, S1 progenies are used for commercial eggplant production in Osaka Prefecture.

• Journal of Microbiology and Biotechnology
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• 제15권1호
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• pp.29-34
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• 2005

W/O/W (water-in-oil-in-water) type multiple emulsion was applied to improve the storage stability of an antagonistic microorganism, Burkholderia gladioli. Encapsulation of microorganism into a W/O/W emulsion was conducted by using a two-step emulsification method. W/O/W emulsion was prepared by the incorporation of B. gladioli into rapeseed oil and the addition of polyglycerin polyriconolate (PGPR) and castor oil polyoxyethylene (COG 25) as the primary and secondary emulsifier, respectively. Microcrystalline cellulose was used as an emulsion stabilizer. To evaluate the usefulness of W/O/W emulsion formulation as a microbial pesticide for controlling the bacterial wilt pathogen (Ralstonia solanacearum), the storage stability and antagonistic activity of emulsion formulation were tested in vitro. The storage stability test revealed that the viability of formulated cells in emulsion was higher than that of unformulated cells in culture broth. At $4^{\circ}C$, the viabilities of formulated cells and unformulated cells at the end of 20 weeks decreased to about 2 and 5 log cycles, respectively. At $37^{\circ}C$, the viability of formulated cells decreased to only 2 log cycles at the end of storage. On the other hand, the viable cells in culture broth were not detected after 13 weeks. In activity test, formulated cells in emulsion were more effective in inhibiting the growth of pathogen than unformulated cells in culture broth. Unformulated cells completely lost their antagonistic activity during storage under similar conditions. The W/O/W multiple emulsion formulation was shown to be useful as the novel liquid formulation for biological control.

• 식물병연구
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• 제12권1호
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• pp.1-4
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• 2006

2001년 이후 2005년까지 북측의 씨감자 생산은 남북 협력으로 순조롭게 진행되어 일부는 이미 3급종자(G3)까지 공급되어 증식되고 있는 실정이다. 특히 씨감자 생산 체계의 상위단계인 조직 배양과 양액씨감자(G0) 생산에서는 성공적이었으며, 다음 단계인 1급(G1)$\sim$4급종자(G4)를 어떻게 무병, 격리 조건에서 감염율을 적게 유지, 증식, 관리하느냐에 달려 있다고 해도 과언이 아닐 것이다. 벌써 상위단게 씨감자 생산의 효과가 나타나기 시작하고 있어, 특히 남북한의 지속적인 협력이 절실하다고 할 수 있다.

• 생물환경조절학회지
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• 제13권1호
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• pp.33-38
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• 2004

본 시험은 고랭지에서 착색단고추의 접목재배로 토경재배시 지하부 환경개선을 통해 토양전염성 병을 예방하고, 수량성을 향상시키고자 저항성 대목들을 수집하여 접목재배하여 생육, 수량 및 병저항성을 비교하였다. 접수는 적색계인 스피리트품종을 사용하였다. 역병균을 접종한 결과 자근묘인 Spirit는 접종 후 5일 만에 100% 고사하였고, 저항성이 높은 대목으로는 탄탄대목, Skurt-S, AC 2258, PST 8301 등 4품종이었다. 또한 청고병에 저항성이 높은 대목으로는 역강, 탄탄대목, TE 412, 갤럭시, MC 4, PST VK, PST NV 등 7품종이었다. 접목구는 지근묘에 비해 근중이 무거워 지하부의 환경개선효과가 뚜렷하였다. 접목과 비접목에 따른 과실의 외적 ${\cdot}$ 내적인 품질은 큰 차이가 없었다. 수량성이 높은 대목은 PST 8301, MC 4, 왕건 등이었다.