Aim: This study was carried out in order to evaluate the potential of bacteriophages in controlling tomato bacterial wilt disease caused by Ralstonia solanacearum. Study design: A purposive sampling technique was used...Aim: This study was carried out in order to evaluate the potential of bacteriophages in controlling tomato bacterial wilt disease caused by Ralstonia solanacearum. Study design: A purposive sampling technique was used to collect samples from bacterial wilt hot spot tomato growing areas in Kenya. Place and duration of study: The research work was done at Jomo Kenyatta University of Agriculture and Technology, between June 2020 and July 2021. Methodology: Thirty diseased plants and corresponding soil were collected from five counties, Nyeri, Kajiado, Nyandarua, Kiambu and Taita Taveta. Bacteria were isolated and characterized, and then used as hosts to propagate the phages. Tests done were gram stain, oxidation test, potassium hydroxide solubility test, H2S production test catalase test, NaCl test and sugar fermentation test. Molecular analysis and phenotyping were also done in order to identify the bacteria. The bacteriophages were then isolated through a double overlay method using R. solanacearum as the host. They were characterized and assayed in a greenhouse setting to determine their effectiveness in controlling bacterial wilt. Results: Six host bacteria were isolated and all belonged to biovar II. Four phages were observed based on morphology. Upon characterization the phages were stable at 30˚C, PH range between 6 - 7 and tolerance of more than an hour under UV light. In the greenhouse experiment, treatment of plants with bacteriophage prevented wilting after subsequent inoculation with the pathogen. A bacteriophage mix of SN1 and WT1 were used for efficacy tests due to their efficiency in plating and infection. Phage SN1 and WT1 exhibited high lytic activity and relatively high thermotolerance and acid tolerance, thereby showing great potential in the biocontrol of bacterial wilt infection across a variety of conditions. Conclusion: The results obtained in this research show that bacteriophages offer potential for the biocontrol of bacterial wilt.展开更多
[ Objective ] The paper was to isolate and identify Ralstonia solanacearum from white burley, and determine its susceptibility to 6 fungicides. [ Mcth- od] Using the combination method of semiselective medium （PCCG）...[ Objective ] The paper was to isolate and identify Ralstonia solanacearum from white burley, and determine its susceptibility to 6 fungicides. [ Mcth- od] Using the combination method of semiselective medium （PCCG） and apolymerase chain reaction （PCR） technique, R. solanacearum in stalk of white burley from Dazhou City in Sichnan Province was isolated, and its biochemical type was identified. Through susceptibility test, the susceptibility of R. solanacearum to bismerthiazol, ethylicin, streptomycin, lime sulfur, 47% polylysine, 99% kojic acid was studied in laboratory. [Result] A total of 23 strains OfR. solanacearum were isolated, all belonging to biochemical type Ill. R. solanacearum obtained in the test were more susceptible to ethylicin, streptomycin and bismerthiazol, and ethylicin had good control effect against R. solanacearum with ECso of 0.086 ml/L. [ Conclusion ] The study provide theoretical basis for control of R. solanaceanon in white burley.展开更多
Bacterial wilt, caused by Ralstonia solanacearum（Rs） is a serious soil-borne disease and silicon can enhance tomato resistance against this disease. However, few studies have focused on the mechanisms of Si-mediated...Bacterial wilt, caused by Ralstonia solanacearum（Rs） is a serious soil-borne disease and silicon can enhance tomato resistance against this disease. However, few studies have focused on the mechanisms of Si-mediated pathogen resistance from the rhizosphere perspective. In this study, two tomato genotypes, HYT（susceptible） and H7996（resistant）, were used to investigate the effects of silicon application on disease inhibition, root growth, and organic acid content in both roots and root exudates under R. solanacearum infection. The results showed that Si application significantly suppressed bacterial wilt in HYT, but had no effect in H7996. Silicon concentrations in roots, stems and leaves of tomato were significantly increased by Si treatment under R. solanacearum inoculation. In HYT, Si application increased root dry weight by 22.8-51.6% and leaf photosynthesis by 30.6-208.0%, and reduced the concentrations of citric acid in root exudates by 71.4% and in roots by 83.5%. However, organic acids did not influence R. solanacearum growth. Results also demonstrated that salicylic acid（SA） content in roots was significantly increased by silicon addition for H7996 and exogenous SA application could reduce bacterial wilt disease index. Collectively, these results suggest that Si-modulated phenolic compound metabolism in roots or root exudates, especially citric acid and SA, may be a potential mechanism in the amelioration of bacterial wilt disease by Si.展开更多
Silicon(Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil micro...Silicon(Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil microbial community component and diversity is not clear. In this study, effects of Si application under R. solanacearum inoculation with or without plant on soil bacterial and fungal communities were investigated through high-throughput pyrosequencing technique. The results showed that Si addition significantly reduced bacterial wilt incidence. However, Si did not reduce the amount of R. solanacearum in rhizosphere soil. Principal components analysis showed that soil microbial community composition was strongly influenced by Si addition. Total 63.7% bacterial operational taxonomic units(OTUs) and 43.8% fungal OTUs were regulated by Si addition regardless of the presence of tomato plants, indicating the independent effects of Si on soil microbial community. Si-added soil harbored a lower abundance of Fusarium, Pseudomonas, and Faecalibacterium. Our finding further demonstrated that exogenous Si could significantly influence soil microbial community component, and this may provide additional insight into the mechanism of Si-enhanced plant resistance against soil-borne pathogens.展开更多
Ralstonia solanacearum causes a lethal bacterial wilt disease in many crops,leading to huge losses in crop production every year.Understanding of plant-R.solanacearum interactions will aid to develop efficient strateg...Ralstonia solanacearum causes a lethal bacterial wilt disease in many crops,leading to huge losses in crop production every year.Understanding of plant-R.solanacearum interactions will aid to develop efficient strategies to control the disease.As a soilborne pathogen,R.solanacearum naturally infects plants via roots.A huge limitation in studying plant-R.solanacearum interactions is the large variation of R.solanacearum infection assay due to the variable soil conditions and uneven inoculum exposure.Here,we developed a robust and reliable Petri-dish inoculation method which allows consistent and stable infection in young plant seedlings.This method is easy to use,takes about only 10 days from seed germination to the completion of inoculation assay,and requires less inoculum of bacteria as well as growth chamber space.We proved the efficacy of the seedling Petri-dish inoculation method by analyzing plant defense primed by molecular patterns,resistance of defense-related plant mutants,and virulence of R.solanacearum mutants.Furthermore,we demonstrated that the seedling Petri-dish inoculation method can be applied to other host plants such as tobacco and has great potential for high-throughput screening of resistant plant germplasms to bacterial wilt in the future.展开更多
Ralstonia solanacearum is a widespread plant bacterial pathogen that can launch a range of type Ⅲ effectors(T3Es)to cause disease.In this study,we isolate a pathogenic R.solanacearum strain named P380 from tomato rhi...Ralstonia solanacearum is a widespread plant bacterial pathogen that can launch a range of type Ⅲ effectors(T3Es)to cause disease.In this study,we isolate a pathogenic R.solanacearum strain named P380 from tomato rhizosphere.Five out of 12 core T3Es of strain P380 are introduced into Pseudomonas syringae DC3000D36E separately to determine their functions in interacting with plants.DC3000D36E that harbors each effector suppresses FliC-triggered Pti5 and ACRE31 expression,ROS burst,and callose deposition.RipAE,RipU,and RipW elicit cell death as well as upregulate the MAPK cascades in Nicotiana benthamiana.The derivatives RipC1^(△DDXDX(T/V))and RipW^(△DDKXXQ)but not RipAE^(K310R) fail to suppress ROS burst.Moreover,RipAE^(K310R) and RipW^(△DDKXXQ) retain the cell death elicitation ability.RipAE and RipW are associated with salicylic acid and jasmonic acid pathways,respectively.RipAE and RipAQ significantly promote the propagation of DC3000D36E in plants.The five core T3Es localize in diverse subcellular organelles of nucleus,plasma membrane,endoplasmic reticulum,and Golgi network.The suppressor of G2 allele of Skp1 is required for RipAE but not RipU-triggered cell death in N.benthamiana.These results indicate that the core T3Es in R.solanacearum play diverse roles in plantpathogen interactions.展开更多
Brown rot or bacterial wilt of potato caused by Ralstonia solanacearum, is an economically important disease. Potato, cv. Nicola, was found to be relatively highly resistant to the infection with R. solanacearum and s...Brown rot or bacterial wilt of potato caused by Ralstonia solanacearum, is an economically important disease. Potato, cv. Nicola, was found to be relatively highly resistant to the infection with R. solanacearum and showed 15.12% wilt disease index, meantime, cv. Kara showed intermediate resistance with 37.40% disease index while, cv. Spunta was susceptible and showed 80.33% disease index. The role of defense-related enzymes in imparting resistance in potato against R. solanacearum was investigated by quantifying enzymes activity and gene expression of three defense- related enzymes, peroxidase, polyphenol oxidase and catalase. Peroxidase showed maximum activity 0.488 min<sup>-1</sup>·g<sup>-1</sup> early at 12 h after pathogen inoculation in the cv. Nicola, whereas in susceptible cultivar Spunta showed lower activity of maximum 0.226 min<sup>-1</sup>·g<sup>-1</sup> later at 48 h after inoculation. While, the moderately resistant cultivar Kara showed intermediate activity for the peak and its time. Meanwhile, polyphenol oxidase showed similar trends to that of peroxidase. On the contrary, catalase showed the highest activity values in the susceptible, cv. Spunta, while, in relatively highly resistant (cv. Nicola) and the moderately resistant (cv. Kara) showed lower values of activity and up to 96 h after inoculation. Meanwhile, gene expression of related enzymes the RT-PCR was used. At zero time, the relatively highly resistant potato cultivar, Nicola, showed the highest values of gene expression for both Peroxidase (POD) and Poly Phenol Oxidase (PPO). While, the susceptible potato cultivar, Spunta showed the lowest values. On the contrary, Catalase (CAT) gene expression was the highest in the susceptible, cv. Spunta, and was the lowest in the relatively highly resistant, cv. Nicola, while, was of intermediate values in the intermediate resistance, cv. Kara. Results show that peroxidase and polyphenol oxidase activities can be used as biochemical markers to reveal the resistance and susceptibility nature of potato cultivars against bacterial wilt disease of potato caused by R. solanacaerum.展开更多
This study is to investigate the role of lipid transfer protein （LTP1） gene of potato （Solanum tuberosum） in bacterial wilt （Ralstonia solanacearum） resistance. A novel cDNA clone encoding nsLTP was isolated fro...This study is to investigate the role of lipid transfer protein （LTP1） gene of potato （Solanum tuberosum） in bacterial wilt （Ralstonia solanacearum） resistance. A novel cDNA clone encoding nsLTP was isolated from cultivated potato （Solanum tuberosum） infected with R. solanacearum by 5＇-rapid amplification of cDNA ends （RACE）. The temporal and spatial expression of StLTPbl was studied during the early stages of potato-R, solanacearum interaction by reverse transcriptase PCR （RT-PCR） and Northern blotting. The sequence analysis of the cloned cDNA, named StLTPbl, showed 691 bp which encoded a type 1 nsLTP of 91 amino acids. Construction of a phylogenic tree showed that StLTPbl is well conserved in the coding region with high identity at the amino acid level with other Solanaceae nsLTPs. The temporal and spatial expression of StLTPbl was studied during the early stages of potato-R, solanacearum interaction. StLTPbl transcription is induced faster and transcripts accumulate to higher concentrations in resistant compared with susceptible genotypes by the pathogen. Dominant differences in the pathogen-induced gene expression pattern between the upper and lower leaves and stems were observed within the same genotypes. In situ hybridization results showed that the StLTPbl mRNA was localized in phloem cells of vascular tissues in potato leaf and stem tissues after pathogen infection. Salicylic acid, methyl jasmonate and abscisic acid could induce StLTPbl gene expression without significant difference between the upper and lower tissues. These abiotic elicitors could produce a long-lastingeffect on the StLTPbl during early stages of potato-R, solanacearum interaction. Differential expression of StLTPbl gene between resistance and susceptible potato genotypes in response to R. solanacearum suggests that this gene plays a key role in plant defense mechanisms.展开更多
Bacterial wilt has become an important obstacle restricting high quality and high yield of cherry tomato. In this paper, the antibacterial activities of ex- tracts from Allium sativum, Ginkgo biloba and Lygodium japon...Bacterial wilt has become an important obstacle restricting high quality and high yield of cherry tomato. In this paper, the antibacterial activities of ex- tracts from Allium sativum, Ginkgo biloba and Lygodium japonicum against Ralstonia solanacearum were compared. The results indicated that with the increasing concentrations of three extracts, the antibacterial effect enhanced gradually. The lowest concentrations of three extracts with the inhibitory effects significantly higher than that of pesticide control were 20% A. sativum extract, 40% G. biloba extract and 60% L japonicum extract, and the antibacterial effect of 20% A. sativum extract was significantly higher than those of other two plant extracts. The inhibition zone diameters of R. solanacearum strains B2. 1.2.2, I1.2. 1.1, KS. 1.1.1 and 1.5.3.1.2 were 9.23, 8.30, 8.12 and 9.19 mm, respectively. The antibacterial effects of three plant extracts reached the maximums when the concentration was 100%, but A. sativum extract had the strongest antibacterial effect against test strains. Therefore, A. sativum can be used as the main raw material for development of plant protectant for cherry tomato.展开更多
Ralstonia solanacearum infecting Davana （Artemisia pallens Wall.） from commercial nurseries in India was isolated on modified semi selective media （SMSA）. Here, we report a new host for Ralstonia solanacearum i.e....Ralstonia solanacearum infecting Davana （Artemisia pallens Wall.） from commercial nurseries in India was isolated on modified semi selective media （SMSA）. Here, we report a new host for Ralstonia solanacearum i.e. davana. It has huge demand in medicinal and aromatic industries. Isolate was confirmed as race-l, biovar-3 by morphological, physiological, biochemical and pathogenicity studies. Two sets of primers （OLI 1 ＆ Y2 and Y 1 ＆ Y2） were used in this study. Further, the identity of the isolate was confirmed by serological diagnostic kit obtained from International Potato Research Center, Lima, Peru and single chain variable fragment antibody specific to Ralstonia solanacearum used to confirm the casual organism.展开更多
One thirty samples (fifty-five potato tubers, twenty-seven potato stems, three chili stems, twenty-eight soil samples, five weed samples, three banana leaves, and nine water samples) were examined and one hundred six ...One thirty samples (fifty-five potato tubers, twenty-seven potato stems, three chili stems, twenty-eight soil samples, five weed samples, three banana leaves, and nine water samples) were examined and one hundred six (106) Bangladeshi isolates of <em>Ralstonia solanacearum</em> were isolated and identified. Isolation was made on selective media (Tetrazolium chloride media) and <em>R. solanacearum</em> was identified based on morphological, pathological and biochemical properties and polymerase chain reaction (PCR) by using the species-specific primers. Studies showed that 81.54% (106) samples were positive on tetrazolium chloride solid medium. Among them 90 isolates were virulent and rest of them were avirulent. Fifty isolates were selected for chemical characterization based on hypersensitivity test. <em>R. solanacearum</em> is gram negative, aerobic facultative bacteria on the basis of chemical characterization. Fifty tested isolates expressed as race 3 while in biovar test forty-eight showed as biovar III and the rest two showed as biovar I. In nine tested isolates from the three districts a species-specific band of 280 bp was amplified in PCR that confirmed the identity of <em>R. solanacerum</em>.展开更多
Ralstonia solanacearum is an important model phytopathogenic bacterium that causes bacterial wilt disease on many plant species and leads to serious economic losses. The interactions between R. solanacearum and host p...Ralstonia solanacearum is an important model phytopathogenic bacterium that causes bacterial wilt disease on many plant species and leads to serious economic losses. The interactions between R. solanacearum and host plants have become a model system for the study of plants and pathogens interactions. This paper reviews the advances on the molecular mechanisms between R. solanacearum and hosts interaction including the formation of plant innate immunity, the suppression of plant innate immunity by this pathogen and the activation of effector-triggered immunity. Furthermore, we made a prospect on how to utilize the interaction mechanism between R. solanacearum and hosts to control the disease.展开更多
文摘Aim: This study was carried out in order to evaluate the potential of bacteriophages in controlling tomato bacterial wilt disease caused by Ralstonia solanacearum. Study design: A purposive sampling technique was used to collect samples from bacterial wilt hot spot tomato growing areas in Kenya. Place and duration of study: The research work was done at Jomo Kenyatta University of Agriculture and Technology, between June 2020 and July 2021. Methodology: Thirty diseased plants and corresponding soil were collected from five counties, Nyeri, Kajiado, Nyandarua, Kiambu and Taita Taveta. Bacteria were isolated and characterized, and then used as hosts to propagate the phages. Tests done were gram stain, oxidation test, potassium hydroxide solubility test, H2S production test catalase test, NaCl test and sugar fermentation test. Molecular analysis and phenotyping were also done in order to identify the bacteria. The bacteriophages were then isolated through a double overlay method using R. solanacearum as the host. They were characterized and assayed in a greenhouse setting to determine their effectiveness in controlling bacterial wilt. Results: Six host bacteria were isolated and all belonged to biovar II. Four phages were observed based on morphology. Upon characterization the phages were stable at 30˚C, PH range between 6 - 7 and tolerance of more than an hour under UV light. In the greenhouse experiment, treatment of plants with bacteriophage prevented wilting after subsequent inoculation with the pathogen. A bacteriophage mix of SN1 and WT1 were used for efficacy tests due to their efficiency in plating and infection. Phage SN1 and WT1 exhibited high lytic activity and relatively high thermotolerance and acid tolerance, thereby showing great potential in the biocontrol of bacterial wilt infection across a variety of conditions. Conclusion: The results obtained in this research show that bacteriophages offer potential for the biocontrol of bacterial wilt.
基金Supported by Sichuan Tobacco Monopoly Bureau Project ( 200901009)~~
文摘[ Objective ] The paper was to isolate and identify Ralstonia solanacearum from white burley, and determine its susceptibility to 6 fungicides. [ Mcth- od] Using the combination method of semiselective medium （PCCG） and apolymerase chain reaction （PCR） technique, R. solanacearum in stalk of white burley from Dazhou City in Sichnan Province was isolated, and its biochemical type was identified. Through susceptibility test, the susceptibility of R. solanacearum to bismerthiazol, ethylicin, streptomycin, lime sulfur, 47% polylysine, 99% kojic acid was studied in laboratory. [Result] A total of 23 strains OfR. solanacearum were isolated, all belonging to biochemical type Ill. R. solanacearum obtained in the test were more susceptible to ethylicin, streptomycin and bismerthiazol, and ethylicin had good control effect against R. solanacearum with ECso of 0.086 ml/L. [ Conclusion ] The study provide theoretical basis for control of R. solanaceanon in white burley.
基金financially supported by grants from the National Natural Science Foundation of China (31370456)the Natural Science Foundation of Guangdong Province, China (2017A030313177)
文摘Bacterial wilt, caused by Ralstonia solanacearum（Rs） is a serious soil-borne disease and silicon can enhance tomato resistance against this disease. However, few studies have focused on the mechanisms of Si-mediated pathogen resistance from the rhizosphere perspective. In this study, two tomato genotypes, HYT（susceptible） and H7996（resistant）, were used to investigate the effects of silicon application on disease inhibition, root growth, and organic acid content in both roots and root exudates under R. solanacearum infection. The results showed that Si application significantly suppressed bacterial wilt in HYT, but had no effect in H7996. Silicon concentrations in roots, stems and leaves of tomato were significantly increased by Si treatment under R. solanacearum inoculation. In HYT, Si application increased root dry weight by 22.8-51.6% and leaf photosynthesis by 30.6-208.0%, and reduced the concentrations of citric acid in root exudates by 71.4% and in roots by 83.5%. However, organic acids did not influence R. solanacearum growth. Results also demonstrated that salicylic acid（SA） content in roots was significantly increased by silicon addition for H7996 and exogenous SA application could reduce bacterial wilt disease index. Collectively, these results suggest that Si-modulated phenolic compound metabolism in roots or root exudates, especially citric acid and SA, may be a potential mechanism in the amelioration of bacterial wilt disease by Si.
基金financially supported by grants from the National Natural Science Foundation of China (31370456)the Doctoral Foundation of the Ministry of Education of China (20124404110007)+1 种基金the Natural Science Foundation of Guangdong Province of China (S2012010010331 and 2017A030313177)the Project of International, as well as Hong Kong, Macao & Taiwan Science and Technology Cooperation Innovation Platform in Universities in Guangdong Province, China (2014KGJHZ004)
文摘Silicon(Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil microbial community component and diversity is not clear. In this study, effects of Si application under R. solanacearum inoculation with or without plant on soil bacterial and fungal communities were investigated through high-throughput pyrosequencing technique. The results showed that Si addition significantly reduced bacterial wilt incidence. However, Si did not reduce the amount of R. solanacearum in rhizosphere soil. Principal components analysis showed that soil microbial community composition was strongly influenced by Si addition. Total 63.7% bacterial operational taxonomic units(OTUs) and 43.8% fungal OTUs were regulated by Si addition regardless of the presence of tomato plants, indicating the independent effects of Si on soil microbial community. Si-added soil harbored a lower abundance of Fusarium, Pseudomonas, and Faecalibacterium. Our finding further demonstrated that exogenous Si could significantly influence soil microbial community component, and this may provide additional insight into the mechanism of Si-enhanced plant resistance against soil-borne pathogens.
基金This work was supported by the National Natural Science Foundation of China(32072399 and 32272641)the Fundamental Research Funds for the Central Universities(GK202201017 and GK202207024)the Program of Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests,China(MIMCP-202203).
文摘Ralstonia solanacearum causes a lethal bacterial wilt disease in many crops,leading to huge losses in crop production every year.Understanding of plant-R.solanacearum interactions will aid to develop efficient strategies to control the disease.As a soilborne pathogen,R.solanacearum naturally infects plants via roots.A huge limitation in studying plant-R.solanacearum interactions is the large variation of R.solanacearum infection assay due to the variable soil conditions and uneven inoculum exposure.Here,we developed a robust and reliable Petri-dish inoculation method which allows consistent and stable infection in young plant seedlings.This method is easy to use,takes about only 10 days from seed germination to the completion of inoculation assay,and requires less inoculum of bacteria as well as growth chamber space.We proved the efficacy of the seedling Petri-dish inoculation method by analyzing plant defense primed by molecular patterns,resistance of defense-related plant mutants,and virulence of R.solanacearum mutants.Furthermore,we demonstrated that the seedling Petri-dish inoculation method can be applied to other host plants such as tobacco and has great potential for high-throughput screening of resistant plant germplasms to bacterial wilt in the future.
基金supported by the National Key R&D Program of China(2019YFD1002000)the Science and Technology Programs of the Shandong Tobacco(KN273)Zunyi Tobacco(2021XM03).
文摘Ralstonia solanacearum is a widespread plant bacterial pathogen that can launch a range of type Ⅲ effectors(T3Es)to cause disease.In this study,we isolate a pathogenic R.solanacearum strain named P380 from tomato rhizosphere.Five out of 12 core T3Es of strain P380 are introduced into Pseudomonas syringae DC3000D36E separately to determine their functions in interacting with plants.DC3000D36E that harbors each effector suppresses FliC-triggered Pti5 and ACRE31 expression,ROS burst,and callose deposition.RipAE,RipU,and RipW elicit cell death as well as upregulate the MAPK cascades in Nicotiana benthamiana.The derivatives RipC1^(△DDXDX(T/V))and RipW^(△DDKXXQ)but not RipAE^(K310R) fail to suppress ROS burst.Moreover,RipAE^(K310R) and RipW^(△DDKXXQ) retain the cell death elicitation ability.RipAE and RipW are associated with salicylic acid and jasmonic acid pathways,respectively.RipAE and RipAQ significantly promote the propagation of DC3000D36E in plants.The five core T3Es localize in diverse subcellular organelles of nucleus,plasma membrane,endoplasmic reticulum,and Golgi network.The suppressor of G2 allele of Skp1 is required for RipAE but not RipU-triggered cell death in N.benthamiana.These results indicate that the core T3Es in R.solanacearum play diverse roles in plantpathogen interactions.
文摘Brown rot or bacterial wilt of potato caused by Ralstonia solanacearum, is an economically important disease. Potato, cv. Nicola, was found to be relatively highly resistant to the infection with R. solanacearum and showed 15.12% wilt disease index, meantime, cv. Kara showed intermediate resistance with 37.40% disease index while, cv. Spunta was susceptible and showed 80.33% disease index. The role of defense-related enzymes in imparting resistance in potato against R. solanacearum was investigated by quantifying enzymes activity and gene expression of three defense- related enzymes, peroxidase, polyphenol oxidase and catalase. Peroxidase showed maximum activity 0.488 min<sup>-1</sup>·g<sup>-1</sup> early at 12 h after pathogen inoculation in the cv. Nicola, whereas in susceptible cultivar Spunta showed lower activity of maximum 0.226 min<sup>-1</sup>·g<sup>-1</sup> later at 48 h after inoculation. While, the moderately resistant cultivar Kara showed intermediate activity for the peak and its time. Meanwhile, polyphenol oxidase showed similar trends to that of peroxidase. On the contrary, catalase showed the highest activity values in the susceptible, cv. Spunta, while, in relatively highly resistant (cv. Nicola) and the moderately resistant (cv. Kara) showed lower values of activity and up to 96 h after inoculation. Meanwhile, gene expression of related enzymes the RT-PCR was used. At zero time, the relatively highly resistant potato cultivar, Nicola, showed the highest values of gene expression for both Peroxidase (POD) and Poly Phenol Oxidase (PPO). While, the susceptible potato cultivar, Spunta showed the lowest values. On the contrary, Catalase (CAT) gene expression was the highest in the susceptible, cv. Spunta, and was the lowest in the relatively highly resistant, cv. Nicola, while, was of intermediate values in the intermediate resistance, cv. Kara. Results show that peroxidase and polyphenol oxidase activities can be used as biochemical markers to reveal the resistance and susceptibility nature of potato cultivars against bacterial wilt disease of potato caused by R. solanacaerum.
基金grateful to Ren Caihong(College of Life Science,Shanxi Normal University of China)for technical assistance.This work was supported by National 863 Program(2003AA207130)Natural Science Foundation of Shanxi Province of China(20051042).
文摘This study is to investigate the role of lipid transfer protein （LTP1） gene of potato （Solanum tuberosum） in bacterial wilt （Ralstonia solanacearum） resistance. A novel cDNA clone encoding nsLTP was isolated from cultivated potato （Solanum tuberosum） infected with R. solanacearum by 5＇-rapid amplification of cDNA ends （RACE）. The temporal and spatial expression of StLTPbl was studied during the early stages of potato-R, solanacearum interaction by reverse transcriptase PCR （RT-PCR） and Northern blotting. The sequence analysis of the cloned cDNA, named StLTPbl, showed 691 bp which encoded a type 1 nsLTP of 91 amino acids. Construction of a phylogenic tree showed that StLTPbl is well conserved in the coding region with high identity at the amino acid level with other Solanaceae nsLTPs. The temporal and spatial expression of StLTPbl was studied during the early stages of potato-R, solanacearum interaction. StLTPbl transcription is induced faster and transcripts accumulate to higher concentrations in resistant compared with susceptible genotypes by the pathogen. Dominant differences in the pathogen-induced gene expression pattern between the upper and lower leaves and stems were observed within the same genotypes. In situ hybridization results showed that the StLTPbl mRNA was localized in phloem cells of vascular tissues in potato leaf and stem tissues after pathogen infection. Salicylic acid, methyl jasmonate and abscisic acid could induce StLTPbl gene expression without significant difference between the upper and lower tissues. These abiotic elicitors could produce a long-lastingeffect on the StLTPbl during early stages of potato-R, solanacearum interaction. Differential expression of StLTPbl gene between resistance and susceptible potato genotypes in response to R. solanacearum suggests that this gene plays a key role in plant defense mechanisms.
文摘Bacterial wilt has become an important obstacle restricting high quality and high yield of cherry tomato. In this paper, the antibacterial activities of ex- tracts from Allium sativum, Ginkgo biloba and Lygodium japonicum against Ralstonia solanacearum were compared. The results indicated that with the increasing concentrations of three extracts, the antibacterial effect enhanced gradually. The lowest concentrations of three extracts with the inhibitory effects significantly higher than that of pesticide control were 20% A. sativum extract, 40% G. biloba extract and 60% L japonicum extract, and the antibacterial effect of 20% A. sativum extract was significantly higher than those of other two plant extracts. The inhibition zone diameters of R. solanacearum strains B2. 1.2.2, I1.2. 1.1, KS. 1.1.1 and 1.5.3.1.2 were 9.23, 8.30, 8.12 and 9.19 mm, respectively. The antibacterial effects of three plant extracts reached the maximums when the concentration was 100%, but A. sativum extract had the strongest antibacterial effect against test strains. Therefore, A. sativum can be used as the main raw material for development of plant protectant for cherry tomato.
文摘Ralstonia solanacearum infecting Davana （Artemisia pallens Wall.） from commercial nurseries in India was isolated on modified semi selective media （SMSA）. Here, we report a new host for Ralstonia solanacearum i.e. davana. It has huge demand in medicinal and aromatic industries. Isolate was confirmed as race-l, biovar-3 by morphological, physiological, biochemical and pathogenicity studies. Two sets of primers （OLI 1 ＆ Y2 and Y 1 ＆ Y2） were used in this study. Further, the identity of the isolate was confirmed by serological diagnostic kit obtained from International Potato Research Center, Lima, Peru and single chain variable fragment antibody specific to Ralstonia solanacearum used to confirm the casual organism.
文摘One thirty samples (fifty-five potato tubers, twenty-seven potato stems, three chili stems, twenty-eight soil samples, five weed samples, three banana leaves, and nine water samples) were examined and one hundred six (106) Bangladeshi isolates of <em>Ralstonia solanacearum</em> were isolated and identified. Isolation was made on selective media (Tetrazolium chloride media) and <em>R. solanacearum</em> was identified based on morphological, pathological and biochemical properties and polymerase chain reaction (PCR) by using the species-specific primers. Studies showed that 81.54% (106) samples were positive on tetrazolium chloride solid medium. Among them 90 isolates were virulent and rest of them were avirulent. Fifty isolates were selected for chemical characterization based on hypersensitivity test. <em>R. solanacearum</em> is gram negative, aerobic facultative bacteria on the basis of chemical characterization. Fifty tested isolates expressed as race 3 while in biovar test forty-eight showed as biovar III and the rest two showed as biovar I. In nine tested isolates from the three districts a species-specific band of 280 bp was amplified in PCR that confirmed the identity of <em>R. solanacerum</em>.
基金Supported by Fundamental Research Funds for the Central Universities(110201202002)
文摘Ralstonia solanacearum is an important model phytopathogenic bacterium that causes bacterial wilt disease on many plant species and leads to serious economic losses. The interactions between R. solanacearum and host plants have become a model system for the study of plants and pathogens interactions. This paper reviews the advances on the molecular mechanisms between R. solanacearum and hosts interaction including the formation of plant innate immunity, the suppression of plant innate immunity by this pathogen and the activation of effector-triggered immunity. Furthermore, we made a prospect on how to utilize the interaction mechanism between R. solanacearum and hosts to control the disease.
