The nascent polypeptide-associated complex(NAC)plays crucial roles in various biological functions in eukaryotes and has been extensively studied in animals and plants;however,its role in the biocontrol mechanisms of ...The nascent polypeptide-associated complex(NAC)plays crucial roles in various biological functions in eukaryotes and has been extensively studied in animals and plants;however,its role in the biocontrol mechanisms of microorganisms requires further investigation.This study examined the function of TbNACα,a NAC subunit,in the biocontrol activity of Trichoderma breve T069 against Sclerotium rolfsii.Following deletion of the TbNACα gene from T.breve T069,the ΔTbNACα mutant exhibited significantly reduced mycelial growth,spore production,and spore germination.While volatile substances from ΔTbNACα showed no significant effect on S.rolfsii,non-volatile substances demonstrated significant inhibition of S.rolfsii growth.Transcriptome sequencing analysis revealed 3,398 differentially expressed genes in the ΔTbNACα mutant compared to wild-type T069,primarily regulating genes associated with secondary metabolite biosynthetic enzymes,hydrolases,and membrane transport proteins.Untargeted metabolomics identified 50 upregulated metabolites(27 in positive ion mode and 23 in negative ion mode)in crude extracts from ΔTbNACα mutant metabolite broth.Among these metabolic substances,ethyl caffeate demonstrated the strongest activity against S.rolfsii,with an EC_(50) of 107.15μg mL^(-1).Quantitative real-time PCR(qPCR)analysis indicated significant upregulation of genes involved in the ethyl caffeate synthesis pathway in ΔTbNACα strains.This research establishes the negative regulation of ethyl caffeate synthesis and elucidates the antagonistic inhibition mechanism of TbNACα in T.breve T069.展开更多
[Objective]The paper was to culture the plasmodia of Physarum pusillum for obtaining the optimal condition of sporophores and sclerotium,to reduce the agricultural diseases.[Method]Liquid culture combined with oat-aga...[Objective]The paper was to culture the plasmodia of Physarum pusillum for obtaining the optimal condition of sporophores and sclerotium,to reduce the agricultural diseases.[Method]Liquid culture combined with oat-agar culture was used to culture plasmodia of P.pusillum.Then plasmodium was induced to obtain Sporophores in lab by hunger and adjusting light（3 000,6 000,9 000,12 000 lx）and temperature（20,22,24,26 ℃）.[Result]Sporophores and sclerotium of P.pusillum were obtained from both oat-agar media and liquid media.The optimal conditions were 26 ℃,6 000 lx and 22 ℃,3 000 lx.[Conclusion]The result provided theoretical basis for reducing the loss of crops caused by myxomycete as much as possible in agricultural production.展开更多
A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insol...A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insoluble β -(1—>3)-D-glucan, sample PCS3- isolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me 2 SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively, to obtain five water-soluble derivatives coded as S-PCS3- C- PCS3- M-PCS3- HE-PCS3- and HP-PCS3- Their chemical structure and distribution of substitution were characterized by infrared spectroscopy (IR), elementary analysis (EA), 1 H-NMR, 13 C-NMR, 2D-COSY, 2D-TOCSY and 2D- 1 H-detected 1H 13C HMQC spectra. The results reveal that the relative reactivity of hydroxyl groups of the β -(1-?3)-D-glucan is in the order C-6 > C-4 > C-2 on the whole. The substitution of the samples S-PCS3- C-PCS3- and M-PCS3- occurred mainly at C-6 position and secondly at C-4 and C-2 positions, and that of HE-PCS3- occurred at C-6 and C-4 positions and of HP-PCS3- almost completely occurred at C-6 position. The degrees of substitution (DS) obtained from 13 C-NMR range from 0.23 to 1.27. The water solubility of the derivatives is in the order S-PCS3- >C-PCS3- >M-PCS3- >HE-PCS3- >HP-PCS3- This work provides a novel and nonpolluting process for the methylation, hydroxyethylation and hydroxypropylation of β -(1—>3)-D-glucan.展开更多
Sclerotium rolfsii Sacc. is a destructive soilborne fungal pathogen with a wide host range that includes peanuts. Biological control offers an interesting alternative to fungicides for sustainable management of soilbo...Sclerotium rolfsii Sacc. is a destructive soilborne fungal pathogen with a wide host range that includes peanuts. Biological control offers an interesting alternative to fungicides for sustainable management of soilborne diseases. The current investigation is aimed at evaluating one potential biocontrol agent Streptomyces sp. RP1 A-12 for growth promotion and the management of peanut stem rot disease caused by S. rolfsii under field conditions. Preliminary studies conducted under in vitro and the greenhouse conditions showed promising results against the stem rot pathogen. Further in vitro and pot experiments conducted to assess Streptomyces sp. RP1 A-12 for its growth promoting abilities using whole organisms have shown an increase in seed germination, root and shoot length. Other parameters like nodule number and plant biomass were also significantly increased over control treatments indicating that the test bioagent possesses growth promoting abilities along with disease suppression capabilities. Subsequently field studies were carried out for two consecutive rainy seasons. The bioagent was applied as whole organism and partially purified crude metabolites. Results indicate the bioagent reduced stem rot disease incidence by 64–67% and 22–49% respectively in two field trials conducted with notable increase in yield. Partially purified Streptomyces sp. RP1 A-12 metabolites exhibited an even greater effect in reducing the incidence and severity of stem rot compared to the pathogen inoculated control.展开更多
本文通过温室盆栽试验,以鳢肠Eclipta prostrata为例,研究杂草叶龄、不同含菌丝体基质接种量以及温度、土壤湿度、保湿期时间等环境因子对菌株SC64侵染鳢肠的影响。在此基础上,温室条件下模拟旱直播水稻田环境下菌株SC64防治节节菜Rotal...本文通过温室盆栽试验,以鳢肠Eclipta prostrata为例,研究杂草叶龄、不同含菌丝体基质接种量以及温度、土壤湿度、保湿期时间等环境因子对菌株SC64侵染鳢肠的影响。在此基础上,温室条件下模拟旱直播水稻田环境下菌株SC64防治节节菜Rotala indica、异型莎草Cyperus difformis、鸭舌草Monochoria vaginalis和耳叶水苋Ammannia arenaria的试验。结果表明,鳢肠幼苗在5叶期以下,接种含菌丝体固体基质剂量在100g m 2以上,温度范围27～33℃,土壤相对饱水90%左右,并且接菌后湿度保持至少24 h,是菌株SC64达到理想除草效果的必需条件。温室模拟试验结果显示,接种含菌丝体固体基质剂量在120 g m 2时,28 d可引起节节菜和鸭舌草81%和74%的植株死亡率及83.8%和82.5%的鲜重抑制率;对异型莎草和耳叶水苋的防效稍差,仅能引起约50%的植株死亡率及60%～65%的鲜重抑制率。这表明菌株SC64可有效控制阔叶杂草,具有开发作为生物除草剂的潜力。展开更多
In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was...In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysisor partially hydrolysis, the derivatives have obvious antitumor activities. The decreasein molecular weight of glucans after periodate modification hardly affects their antitumoractions, but on the other hand, the decrease of molecular weight without periodate modi-fication could lead to an enhancement of the antitumor activities. Moreover, the glucansand these derivatives have much higher enhancement ratios of body weight of mice thanthat of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.展开更多
In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were inve...In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.展开更多
Tomato(Solanum lycopersicum)is one of the most widely grown and consumed as fresh vegetable in the world.Sclerotium rolfsii Sacc.is one of the most destructive diseases and affects more than 500 plant species.This stu...Tomato(Solanum lycopersicum)is one of the most widely grown and consumed as fresh vegetable in the world.Sclerotium rolfsii Sacc.is one of the most destructive diseases and affects more than 500 plant species.This study was conducted for“Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistant to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato”.The experiment was conducted at the Royal University of Agriculture and divided into two sections.The first section conducted under in vitro condition consists of four treatments T1 control treatment,T2 copper hydroxide,T3 azoxystrobin+difenoconazole,T4 metalaxyl+mancozeb in Nagoya Laboratory,and had been starting from 11st May to 15th May 2020.Section two was conducted in a pot in net-house which started from 1st January 2019 to 19th February 2019 and 1st January to 19th February 2020 and arranged in RCBD(Randomized Completely Block Design)with six replications and nine treatments.T0 negative control,T1 inoculate but not treatment,T2 metalaxyl+mancozeb,T3 azoxystrobin+difenoconazole,T4 copper hydroxide,T5 acibenzolar-S-methyl,T6 chicken dung+Trichoderma harzianum,T7 acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,T8 acibenzolar-S-methyl+metalaxyl+mancozeb.Data were collected on colonizing diameter in vitro.For pot experiment collected on disease incidence,incubation period Based on the result under in vitro condition metalaxyl+mancozeb highly inhibited germination of Sclerotium rolfsii when compared with another treatment.However,the application of copper hydroxide seems less effective compared with control.For in pot experiment,when treated after symptom of southern blight appeared to seem less effective on the severity of southern blight.In contrast,when applied as a protectant and curative when symptoms appeared only systemic fungicide azoxystrobin+difenoconazole significantly reduced the severity of Sclerotium rolfsii and delayed incubation period while compared with other treatments(p<0.05)and was followed by metalaxyl+mancozeb,whereas,copper hydroxide,acibenzolar-S-methyl,chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+metalaxyl+mancozeb were less effective(p>0.05).Based on the three experiments we can assume that fungicide is more effective in reducing the growth of the pathogen and delaying the incubation period of fungal colonization when compared with biological control and induced resistance.展开更多
Scleroglucan is an extracellular polysaccharide produced by the fungi Sclerotium.Scleroglucan is stable over a broad range of temperatures,pH and salt concentration,thus having great potential in many diverse applicat...Scleroglucan is an extracellular polysaccharide produced by the fungi Sclerotium.Scleroglucan is stable over a broad range of temperatures,pH and salt concentration,thus having great potential in many diverse applications.Common media for scleroglucan production contain expensive components,such as yeast extract,that make the medium cost-ineffective for some industrial applications.Thus we developed a medium which uses Condensed Corn Solubles(CCS),a nutrient-rich byproduct of corn-based ethanol production,to replace expensive components.Methods typically used to recover scleroglucan are also expensive,and can limit commercialization.To evaluate alternative processes for scleroglucan recovery,we prepared scleroglucan in a modified version of Wang’s medium and a CCS-glucose medium.Broth samples were initially subjected to the standard recovery method to develop a complete mass balance,and then we evaluated various treatments to improve scleroglucan recovery.These included heat treatments to lyse cells,using different alcohol precipitants,freezing or refrigerating before recovery,and diluting broth to enhance cell separation.The CCS medium produced 14.2 g/L scleroglucan,compared to 10.1 g/L in the modified Wang’s medium.Based on the standard recovery protocol,we determined that 96%of the scleroglucan was recovered from the initial centrifugation and precipitation.Washing the cell pellet with water and recentrifuging only recovered a minimal amount of scleroglucan,and thus it could be eliminated from protocol to save energy and costs.Lysing cells by boiling or autoclaving did not release more scleroglucan than un-heated samples,and we also found no statistical difference between ethanol,isopopanol,and methanol as scleroglucan precipitants.Refrigerating the broth prior to scleroglucan recovery had no significant effect,while freezing actually decreased scleroglucan recovery.Initially diluting the broth by 0.50 or 0.34 resulted in the greatest scleroglucan recovery,while higher or lower dilutions decreased recovery.The optimum protocol for scleroglucan recovery was a 0.50 dilution of broth prior to centrifugation,no washing of the cell pellet,and use of the least expensive alcohol to precipitate scleroglucan from the supernatant.展开更多
基金supported by the National Natural Science Foundation of China(32060589).
文摘The nascent polypeptide-associated complex(NAC)plays crucial roles in various biological functions in eukaryotes and has been extensively studied in animals and plants;however,its role in the biocontrol mechanisms of microorganisms requires further investigation.This study examined the function of TbNACα,a NAC subunit,in the biocontrol activity of Trichoderma breve T069 against Sclerotium rolfsii.Following deletion of the TbNACα gene from T.breve T069,the ΔTbNACα mutant exhibited significantly reduced mycelial growth,spore production,and spore germination.While volatile substances from ΔTbNACα showed no significant effect on S.rolfsii,non-volatile substances demonstrated significant inhibition of S.rolfsii growth.Transcriptome sequencing analysis revealed 3,398 differentially expressed genes in the ΔTbNACα mutant compared to wild-type T069,primarily regulating genes associated with secondary metabolite biosynthetic enzymes,hydrolases,and membrane transport proteins.Untargeted metabolomics identified 50 upregulated metabolites(27 in positive ion mode and 23 in negative ion mode)in crude extracts from ΔTbNACα mutant metabolite broth.Among these metabolic substances,ethyl caffeate demonstrated the strongest activity against S.rolfsii,with an EC_(50) of 107.15μg mL^(-1).Quantitative real-time PCR(qPCR)analysis indicated significant upregulation of genes involved in the ethyl caffeate synthesis pathway in ΔTbNACα strains.This research establishes the negative regulation of ethyl caffeate synthesis and elucidates the antagonistic inhibition mechanism of TbNACα in T.breve T069.
基金Supported by National Natural Science Foundation of China(70670015,71070012)~~
文摘[Objective]The paper was to culture the plasmodia of Physarum pusillum for obtaining the optimal condition of sporophores and sclerotium,to reduce the agricultural diseases.[Method]Liquid culture combined with oat-agar culture was used to culture plasmodia of P.pusillum.Then plasmodium was induced to obtain Sporophores in lab by hunger and adjusting light（3 000,6 000,9 000,12 000 lx）and temperature（20,22,24,26 ℃）.[Result]Sporophores and sclerotium of P.pusillum were obtained from both oat-agar media and liquid media.The optimal conditions were 26 ℃,6 000 lx and 22 ℃,3 000 lx.[Conclusion]The result provided theoretical basis for reducing the loss of crops caused by myxomycete as much as possible in agricultural production.
基金This work was supported by the National Natural Science Foundation of China (No. 20074025), the Area of Excellence(AoE) on Plant and Fungal Biotechnology Project of the Hong Kong SAR Government and Key Laboratory of Cellulose andLignocellulosic Chemistry of Chinese Academy of Sciences.
文摘A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insoluble β -(1—>3)-D-glucan, sample PCS3- isolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me 2 SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively, to obtain five water-soluble derivatives coded as S-PCS3- C- PCS3- M-PCS3- HE-PCS3- and HP-PCS3- Their chemical structure and distribution of substitution were characterized by infrared spectroscopy (IR), elementary analysis (EA), 1 H-NMR, 13 C-NMR, 2D-COSY, 2D-TOCSY and 2D- 1 H-detected 1H 13C HMQC spectra. The results reveal that the relative reactivity of hydroxyl groups of the β -(1-?3)-D-glucan is in the order C-6 > C-4 > C-2 on the whole. The substitution of the samples S-PCS3- C-PCS3- and M-PCS3- occurred mainly at C-6 position and secondly at C-4 and C-2 positions, and that of HE-PCS3- occurred at C-6 and C-4 positions and of HP-PCS3- almost completely occurred at C-6 position. The degrees of substitution (DS) obtained from 13 C-NMR range from 0.23 to 1.27. The water solubility of the derivatives is in the order S-PCS3- >C-PCS3- >M-PCS3- >HE-PCS3- >HP-PCS3- This work provides a novel and nonpolluting process for the methylation, hydroxyethylation and hydroxypropylation of β -(1—>3)-D-glucan.
基金Biotechnology Industry Research Assistance Council (BIRAC), a government of India enterprise, for providing financial support under Biotechnology Industry Partnership Programme (BIPP) (BT/BIPP0429/11/10)
文摘Sclerotium rolfsii Sacc. is a destructive soilborne fungal pathogen with a wide host range that includes peanuts. Biological control offers an interesting alternative to fungicides for sustainable management of soilborne diseases. The current investigation is aimed at evaluating one potential biocontrol agent Streptomyces sp. RP1 A-12 for growth promotion and the management of peanut stem rot disease caused by S. rolfsii under field conditions. Preliminary studies conducted under in vitro and the greenhouse conditions showed promising results against the stem rot pathogen. Further in vitro and pot experiments conducted to assess Streptomyces sp. RP1 A-12 for its growth promoting abilities using whole organisms have shown an increase in seed germination, root and shoot length. Other parameters like nodule number and plant biomass were also significantly increased over control treatments indicating that the test bioagent possesses growth promoting abilities along with disease suppression capabilities. Subsequently field studies were carried out for two consecutive rainy seasons. The bioagent was applied as whole organism and partially purified crude metabolites. Results indicate the bioagent reduced stem rot disease incidence by 64–67% and 22–49% respectively in two field trials conducted with notable increase in yield. Partially purified Streptomyces sp. RP1 A-12 metabolites exhibited an even greater effect in reducing the incidence and severity of stem rot compared to the pathogen inoculated control.
文摘本文通过温室盆栽试验,以鳢肠Eclipta prostrata为例,研究杂草叶龄、不同含菌丝体基质接种量以及温度、土壤湿度、保湿期时间等环境因子对菌株SC64侵染鳢肠的影响。在此基础上,温室条件下模拟旱直播水稻田环境下菌株SC64防治节节菜Rotala indica、异型莎草Cyperus difformis、鸭舌草Monochoria vaginalis和耳叶水苋Ammannia arenaria的试验。结果表明,鳢肠幼苗在5叶期以下,接种含菌丝体固体基质剂量在100g m 2以上,温度范围27～33℃,土壤相对饱水90%左右,并且接菌后湿度保持至少24 h,是菌株SC64达到理想除草效果的必需条件。温室模拟试验结果显示,接种含菌丝体固体基质剂量在120 g m 2时,28 d可引起节节菜和鸭舌草81%和74%的植株死亡率及83.8%和82.5%的鲜重抑制率;对异型莎草和耳叶水苋的防效稍差,仅能引起约50%的植株死亡率及60%～65%的鲜重抑制率。这表明菌株SC64可有效控制阔叶杂草,具有开发作为生物除草剂的潜力。
基金This work was supported by the National Natural Science Foundation of China
文摘In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysisor partially hydrolysis, the derivatives have obvious antitumor activities. The decreasein molecular weight of glucans after periodate modification hardly affects their antitumoractions, but on the other hand, the decrease of molecular weight without periodate modi-fication could lead to an enhancement of the antitumor activities. Moreover, the glucansand these derivatives have much higher enhancement ratios of body weight of mice thanthat of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.
基金supported by Central Public-interest Scientific Institution Basal Research Fund (1610172021003)Supported by the earmarked fund for CARS-13Key Area Research and Development Program of Hubei Province (2021BBA077)
文摘In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.
基金iDE Cambodia(International Development Enterprises)and the Integrated Pest Management Innovation Lab funding my thesis experiments.
文摘Tomato(Solanum lycopersicum)is one of the most widely grown and consumed as fresh vegetable in the world.Sclerotium rolfsii Sacc.is one of the most destructive diseases and affects more than 500 plant species.This study was conducted for“Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistant to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato”.The experiment was conducted at the Royal University of Agriculture and divided into two sections.The first section conducted under in vitro condition consists of four treatments T1 control treatment,T2 copper hydroxide,T3 azoxystrobin+difenoconazole,T4 metalaxyl+mancozeb in Nagoya Laboratory,and had been starting from 11st May to 15th May 2020.Section two was conducted in a pot in net-house which started from 1st January 2019 to 19th February 2019 and 1st January to 19th February 2020 and arranged in RCBD(Randomized Completely Block Design)with six replications and nine treatments.T0 negative control,T1 inoculate but not treatment,T2 metalaxyl+mancozeb,T3 azoxystrobin+difenoconazole,T4 copper hydroxide,T5 acibenzolar-S-methyl,T6 chicken dung+Trichoderma harzianum,T7 acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,T8 acibenzolar-S-methyl+metalaxyl+mancozeb.Data were collected on colonizing diameter in vitro.For pot experiment collected on disease incidence,incubation period Based on the result under in vitro condition metalaxyl+mancozeb highly inhibited germination of Sclerotium rolfsii when compared with another treatment.However,the application of copper hydroxide seems less effective compared with control.For in pot experiment,when treated after symptom of southern blight appeared to seem less effective on the severity of southern blight.In contrast,when applied as a protectant and curative when symptoms appeared only systemic fungicide azoxystrobin+difenoconazole significantly reduced the severity of Sclerotium rolfsii and delayed incubation period while compared with other treatments(p<0.05)and was followed by metalaxyl+mancozeb,whereas,copper hydroxide,acibenzolar-S-methyl,chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+metalaxyl+mancozeb were less effective(p>0.05).Based on the three experiments we can assume that fungicide is more effective in reducing the growth of the pathogen and delaying the incubation period of fungal colonization when compared with biological control and induced resistance.
基金supported by the South Dakota Corn Utilization Council and by the South Dakota Agricultural Experiment Station,grant no.SD00151-H.
文摘Scleroglucan is an extracellular polysaccharide produced by the fungi Sclerotium.Scleroglucan is stable over a broad range of temperatures,pH and salt concentration,thus having great potential in many diverse applications.Common media for scleroglucan production contain expensive components,such as yeast extract,that make the medium cost-ineffective for some industrial applications.Thus we developed a medium which uses Condensed Corn Solubles(CCS),a nutrient-rich byproduct of corn-based ethanol production,to replace expensive components.Methods typically used to recover scleroglucan are also expensive,and can limit commercialization.To evaluate alternative processes for scleroglucan recovery,we prepared scleroglucan in a modified version of Wang’s medium and a CCS-glucose medium.Broth samples were initially subjected to the standard recovery method to develop a complete mass balance,and then we evaluated various treatments to improve scleroglucan recovery.These included heat treatments to lyse cells,using different alcohol precipitants,freezing or refrigerating before recovery,and diluting broth to enhance cell separation.The CCS medium produced 14.2 g/L scleroglucan,compared to 10.1 g/L in the modified Wang’s medium.Based on the standard recovery protocol,we determined that 96%of the scleroglucan was recovered from the initial centrifugation and precipitation.Washing the cell pellet with water and recentrifuging only recovered a minimal amount of scleroglucan,and thus it could be eliminated from protocol to save energy and costs.Lysing cells by boiling or autoclaving did not release more scleroglucan than un-heated samples,and we also found no statistical difference between ethanol,isopopanol,and methanol as scleroglucan precipitants.Refrigerating the broth prior to scleroglucan recovery had no significant effect,while freezing actually decreased scleroglucan recovery.Initially diluting the broth by 0.50 or 0.34 resulted in the greatest scleroglucan recovery,while higher or lower dilutions decreased recovery.The optimum protocol for scleroglucan recovery was a 0.50 dilution of broth prior to centrifugation,no washing of the cell pellet,and use of the least expensive alcohol to precipitate scleroglucan from the supernatant.
