[Objective] The paper was to explore the effect of different culture conditions on sporulation quantity of Phytophthora capsici in Capsicum annuum L.var.dactylus M.in Xunhua.[Method] The effects of light hours,pH,medi...[Objective] The paper was to explore the effect of different culture conditions on sporulation quantity of Phytophthora capsici in Capsicum annuum L.var.dactylus M.in Xunhua.[Method] The effects of light hours,pH,medium and temperature on sporulation quantity during isolation and culture process of P.capsici were studied.[Result] The sporulation quantity of P.capsici under the conditions of 24 h/day light,pH 7.0,potato medium（PSA） and 30 ℃ was the largest,and pH,basal medium and temperature had greater impact on sporulation quantity.[Conclusion]The study laid foundation for the study on natural incidence condition of C.annuum in Xunhua.展开更多
Laboratory studies were conducted to evaluate the risk of Phytophthora capsici developing resistance to two morphlines, dimethomorph and flumorph. Metalaxyl, the well-known high risk of resistance fungicides, was used...Laboratory studies were conducted to evaluate the risk of Phytophthora capsici developing resistance to two morphlines, dimethomorph and flumorph. Metalaxyl, the well-known high risk of resistance fungicides, was used as reference fungicide. Resistant mutants for the three fungicides were isolated by treating mycelium with ultraviolet radiation. Metalaxyl-resistant mutants were obtained with high frequency and exhibited high level of resistance with factors more than 100 folds, while mutation frequency for dimethomorph-resistance was relatively low and the resistance factors ranged from 3.0 to 13.9 folds. Most dimethomorph-resistant mutants decreased in hyphal growth rate and the spoulation ability, which have a large impact upon the epidemic development of dimethomorph-resistant populations. These results suggested that the risk of resistant pathogen population was much lower for dimethomorph than for metalaxyl. Both the frequency of developing resistance and level of resistance （resistance factors = 1.8-14.6） to dimethomorph were similar to those of its structure analogue flumorh. Moreover, the cross-resistance were found between them, which suggested the risks of developing resistance to dimethomorph and flumorph in the pathogen were very closely related. As P. capsici can potentially develop resistance to dimethomorph and flumorph, and oomycetes usually have the high risk to develop resistance to fungicides, appropriate management against resistance development should be taken.展开更多
The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus of Glomus intraradices and/or infection with pathogenic strain of Phytophthora capsici, and th...The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus of Glomus intraradices and/or infection with pathogenic strain of Phytophthora capsici, and the biological control effect of G. intraradices on Phytophthora blight in pepper were investigated. The experiment was carried out with four treatments: (1) plants pre-inoculated with G. intraradices (Gi), (2) plants pre-inoculated with G. intraradices and then infected with P. capsici (Gi+Pc), (3) plants infected with P. capsici (Pc), and (4) plants without any of the two microorganisms (C). Mycorrhizal coloni-zation rate was reduced by about 10% in pathogen challenged plants. Root mortality caused by infection of P. capsici was com-pletely eliminated by pre-inoculation with antagonistic G. intraradices. On the ninth day after pathogen infection, Peroxidase (POD) activity increased by 116.9% in Pc-treated roots but by only 21.2% in Gi+Pc-treated roots, compared with the control, respectively. Polyphenol oxidase (PPO) and Phenylalanine ammonia-lyase (PAL) activities gradually increased during the first 3 d and dramatically decreased in Pc-treated roots but slightly decreased in Gi+Pc-treated roots, respectively. On the ninth day after pathogen infection, PPO and PAL decreased by 62.8% and 73.9% in Pc-treated roots but by only 19.8% and 19.5% in Gi+Pc-treated roots, compared with the control, respectively. Three major POD isozymes (45 000, 53 000 and 114 000) were present in Pc-treated roots, while two major bands (53 000 and 114 000) and one minor band (45 000) were present in spectra of Gi+Pc-treated roots, the 45 000 POD isozyme was significantly suppressed by G. intraradices, suggesting that the 45 000 POD isozyme was induced by the pathogen infection but not induced by the antagonistic G. intraradices. A 60 000 PPO isozyme was induced in Pc-treated roots but not induced in Gi+Pc-treated roots. All these results showed the inoculation of antagonistic G. intraradices alleviates root mortality, activates changes of lignification-related enzymes and induces some of the isozymes in pepper plants infected by P. capsici. The results suggested that G. intraradices is a potentially effective protection agent against P. capsici.展开更多
Black pepper is the one of most important export products in Vietnam. As the largest exporter, Vietnam’s pepper commodities account for 58% of total worldwide exporters. However, Vietnam’s pepper production is deali...Black pepper is the one of most important export products in Vietnam. As the largest exporter, Vietnam’s pepper commodities account for 58% of total worldwide exporters. However, Vietnam’s pepper production is dealing with disease problems, especially foot rot/quick death infected by Phytophthora capsici. The disease results in serious and rapid spread and infection in Vietnam, with yearly reduction of about 2% of total pepper area. Disease management is recently challenging scientists and producers. Investigating characteristics of Phytophthora capsici and causes, therefore, play a significant role in treatment. This paper has indicated three main causes, which contribute to serious infection and outbreak of Phytophthora capsici;they are biological characteristics, climatic condition and cultivation. To control this disease, early detection and prevention are the best ways to manage disease. Finding new varieties, which are Phytophthora capsici tolerance or resistance, is significant in black pepper production worldwide.展开更多
By growth rate method, the inhibitory effects of five solvent extracts from Helianthus tuberosus leaves against Phytophthora capsici were studied in the test. The results showed that different solvent extracts all had...By growth rate method, the inhibitory effects of five solvent extracts from Helianthus tuberosus leaves against Phytophthora capsici were studied in the test. The results showed that different solvent extracts all had inhibitory effect against P. capsici, while 12.5 mg/mL of extracts from H. tuberosus leaves with petroleum ether and ethyl acetate as solvents had the highest inhibitory effect against P. capsici, reaching 100%. In case of various solvent extracts with different concentration gradients, ethyl acetate extract had the most significant inhibitory effect; when the concentration was 5 mg/mL, the inhibitory effect of ethyl acetate extract had reached 100% ; when the concentration reduced to 2.5 mg/mL, the inhibitory effect was still （27.91 ±2. 076） %, significantly higher than that of other solvent extracts at the same concentration. The 50 times dilution of ethyl acetate extract from H. tuberosus leaves was selected for pot test against pepper blight. , and the results showed that its control effect against pepper blight reached 100.00%, superior than that of chemical agent 25% metalaxyl WP 400 times dilution.展开更多
Ten random primers with clear amplification profile, significant and stable main band were screened from RAPD （Random Amplified Polymorphie DNAs） primers to analyze the genetic diversity among eight Phytophthora cap...Ten random primers with clear amplification profile, significant and stable main band were screened from RAPD （Random Amplified Polymorphie DNAs） primers to analyze the genetic diversity among eight Phytophthora capsici isolates from Huaxi District, Wudang District and Kaiyang County of Guiyang City, and Zunyi County, Suiyang County and Luodian County of Zunyi City in Guizhou Province. A total of 70 DNA fingerprints were obtained, including 57 polymorphic bands, with a polymorphic percentage of 81.43%, suggesting abundant genetic diversity among experimental Phytophthora capsici isolates. According to the ampli- fied DNA fingerprint profiles, using genetic similarity coefficient 0.5 as the threshold, experimental Phytophthora capsici isolates were clustered into three genetic categories by UPGMA cluster analysis. The analysis result indicated that there was no direct correlation between the genetic similarity and cultivation areas of vari- ous Phytophthora caosici isolates.展开更多
Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phyto...Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phytophthora capsici. Differences in root rot, stem blight and foliar blight severities among accessions were significant. The accessions consistently differentiated into two groups across the three disease syndromes. Simple sequence repeat (SSR) markers showed variability both within and between accessions of California Wonder. The variability in the responses to the three forms of Phytophthora blight does not warrant its usefulness as a standard susceptible control in studies involving the Capsicum-P. capsici patho-system.展开更多
The internal transcribed spacer （ITS） region （ITS1, ITS2 and 5.8S rDNA） of the nuclear ribosomal DNA （nrDNA） was amplified via the PCR method in seventeen different isolates of Phytophthora sojae using the commo...The internal transcribed spacer （ITS） region （ITS1, ITS2 and 5.8S rDNA） of the nuclear ribosomal DNA （nrDNA） was amplified via the PCR method in seventeen different isolates of Phytophthora sojae using the common primers of the ITS of fungi. Around 800 bp- 1,000 bp fragments were obtained based on the DL2000 marker and the sequences of the PCR products were tested. Taking isolate USA as outgroup, the phylogenetic tree was constructed by means of maximum parsimony analysis, and the genetic evolution among isolates was analyzed. The results showed that there is a great difference between the base constitution of ITS 1 and ITS2 among various isolates. The seventeen isolates are classified into three groups, and the isolates from the same region belong to the same group, which shows the variation in geography.展开更多
A complete cDNA of potato Phytophthora infestans-induced hypersensitive response-related protein gene (POTHR-1) was cloned using rapid amplification of cDNA ends (RACE) strategy according to a fragment sequence which ...A complete cDNA of potato Phytophthora infestans-induced hypersensitive response-related protein gene (POTHR-1) was cloned using rapid amplification of cDNA ends (RACE) strategy according to a fragment sequence which we had cloned using suppression subtractive hybridization (SSH) technique. The potato POTHR-1 gene encodes a protein of 225 amino acids, which shares 81% identity with tobacco hin1 gene-enoded protein (harpin-induced protein). Southern blot revealed that there are two to three copies of POTHR-1 in potato genome. The POTHR-1 gene expression in potato leaves showed that its transcripts accumulated remarkably in leaves after 36 h inoculation with P. infestans. Mechanical wounding and jasmonic acid (JA) could induce the POTHR-1 gene expression and osmotic stress just induce a slight accumulation of POTHR-1 gene mRNA, while salicylic acid (SA) had no detectable function on the induction accumulation of POTHR-1 gene transcripts. The potato POTHR-1 gene may preferentially associate with hypersensitive response (HR) or biotic cell death during interaction between host and pathogen.展开更多
[ Objective ] The paper was to screen bacterial strain with significant antagonistic effect against Phytophthora infestans, so as to provide basis for further development and utilization of antagonistic bacteria to in...[ Objective ] The paper was to screen bacterial strain with significant antagonistic effect against Phytophthora infestans, so as to provide basis for further development and utilization of antagonistic bacteria to inhibit P. infestans and control potato late bright. [ Method] Plate dual culture and filter paper method were used to determine the inhibition effect of strains in vivo, fermentation broth and bacterial liquid of 61 strains against P. infestans and the resistance-induction effect of SR13-2 strain. [ Result] The inhibition rate of 24 strains among 61 tested strains against mycelial growth of P. infestans was greater than 60%, and the inhibi- tion effect of HT-6 strain was the strongest with the inhibition rate of 89.92%. However, fermentation broth of all tested strains had no significant inhibition effect against P. infestans, while the inhibition effect of bacterial liquid of most strains was significantly higher than strain in vivo; the inhibition effect of $34-1 strain was the strongest with inhibition rate of 91.50%. The bacterial liquid of SR13-2 strain was found to have significant resistance-induction effect with protective rate of 60%. [ Conclusion] The inhibition effect of strains in vivo and fermentation broth of antagonistic strains S34-1 and SR13-2 had no relationship with each other, while bacterial liquid had great application potential in controlling potato late bright.展开更多
文摘[Objective] The paper was to explore the effect of different culture conditions on sporulation quantity of Phytophthora capsici in Capsicum annuum L.var.dactylus M.in Xunhua.[Method] The effects of light hours,pH,medium and temperature on sporulation quantity during isolation and culture process of P.capsici were studied.[Result] The sporulation quantity of P.capsici under the conditions of 24 h/day light,pH 7.0,potato medium（PSA） and 30 ℃ was the largest,and pH,basal medium and temperature had greater impact on sporulation quantity.[Conclusion]The study laid foundation for the study on natural incidence condition of C.annuum in Xunhua.
基金This study was supported by China Postdoctoral Science Foundation(20040350377)National Natural Science Foundation of China(30400294).
文摘Laboratory studies were conducted to evaluate the risk of Phytophthora capsici developing resistance to two morphlines, dimethomorph and flumorph. Metalaxyl, the well-known high risk of resistance fungicides, was used as reference fungicide. Resistant mutants for the three fungicides were isolated by treating mycelium with ultraviolet radiation. Metalaxyl-resistant mutants were obtained with high frequency and exhibited high level of resistance with factors more than 100 folds, while mutation frequency for dimethomorph-resistance was relatively low and the resistance factors ranged from 3.0 to 13.9 folds. Most dimethomorph-resistant mutants decreased in hyphal growth rate and the spoulation ability, which have a large impact upon the epidemic development of dimethomorph-resistant populations. These results suggested that the risk of resistant pathogen population was much lower for dimethomorph than for metalaxyl. Both the frequency of developing resistance and level of resistance （resistance factors = 1.8-14.6） to dimethomorph were similar to those of its structure analogue flumorh. Moreover, the cross-resistance were found between them, which suggested the risks of developing resistance to dimethomorph and flumorph in the pathogen were very closely related. As P. capsici can potentially develop resistance to dimethomorph and flumorph, and oomycetes usually have the high risk to develop resistance to fungicides, appropriate management against resistance development should be taken.
基金Project supported by Korea Science and Engineering Foundation(KOSEF) through the Agricultural Plants Stress Research Center(APSRC) at Chonnam National University, Korea
文摘The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus of Glomus intraradices and/or infection with pathogenic strain of Phytophthora capsici, and the biological control effect of G. intraradices on Phytophthora blight in pepper were investigated. The experiment was carried out with four treatments: (1) plants pre-inoculated with G. intraradices (Gi), (2) plants pre-inoculated with G. intraradices and then infected with P. capsici (Gi+Pc), (3) plants infected with P. capsici (Pc), and (4) plants without any of the two microorganisms (C). Mycorrhizal coloni-zation rate was reduced by about 10% in pathogen challenged plants. Root mortality caused by infection of P. capsici was com-pletely eliminated by pre-inoculation with antagonistic G. intraradices. On the ninth day after pathogen infection, Peroxidase (POD) activity increased by 116.9% in Pc-treated roots but by only 21.2% in Gi+Pc-treated roots, compared with the control, respectively. Polyphenol oxidase (PPO) and Phenylalanine ammonia-lyase (PAL) activities gradually increased during the first 3 d and dramatically decreased in Pc-treated roots but slightly decreased in Gi+Pc-treated roots, respectively. On the ninth day after pathogen infection, PPO and PAL decreased by 62.8% and 73.9% in Pc-treated roots but by only 19.8% and 19.5% in Gi+Pc-treated roots, compared with the control, respectively. Three major POD isozymes (45 000, 53 000 and 114 000) were present in Pc-treated roots, while two major bands (53 000 and 114 000) and one minor band (45 000) were present in spectra of Gi+Pc-treated roots, the 45 000 POD isozyme was significantly suppressed by G. intraradices, suggesting that the 45 000 POD isozyme was induced by the pathogen infection but not induced by the antagonistic G. intraradices. A 60 000 PPO isozyme was induced in Pc-treated roots but not induced in Gi+Pc-treated roots. All these results showed the inoculation of antagonistic G. intraradices alleviates root mortality, activates changes of lignification-related enzymes and induces some of the isozymes in pepper plants infected by P. capsici. The results suggested that G. intraradices is a potentially effective protection agent against P. capsici.
文摘Black pepper is the one of most important export products in Vietnam. As the largest exporter, Vietnam’s pepper commodities account for 58% of total worldwide exporters. However, Vietnam’s pepper production is dealing with disease problems, especially foot rot/quick death infected by Phytophthora capsici. The disease results in serious and rapid spread and infection in Vietnam, with yearly reduction of about 2% of total pepper area. Disease management is recently challenging scientists and producers. Investigating characteristics of Phytophthora capsici and causes, therefore, play a significant role in treatment. This paper has indicated three main causes, which contribute to serious infection and outbreak of Phytophthora capsici;they are biological characteristics, climatic condition and cultivation. To control this disease, early detection and prevention are the best ways to manage disease. Finding new varieties, which are Phytophthora capsici tolerance or resistance, is significant in black pepper production worldwide.
基金Supported by Applied Basic Research Project of Qinghai Provincial Science and Technology Department(2014-ZJ-735)
文摘By growth rate method, the inhibitory effects of five solvent extracts from Helianthus tuberosus leaves against Phytophthora capsici were studied in the test. The results showed that different solvent extracts all had inhibitory effect against P. capsici, while 12.5 mg/mL of extracts from H. tuberosus leaves with petroleum ether and ethyl acetate as solvents had the highest inhibitory effect against P. capsici, reaching 100%. In case of various solvent extracts with different concentration gradients, ethyl acetate extract had the most significant inhibitory effect; when the concentration was 5 mg/mL, the inhibitory effect of ethyl acetate extract had reached 100% ; when the concentration reduced to 2.5 mg/mL, the inhibitory effect was still （27.91 ±2. 076） %, significantly higher than that of other solvent extracts at the same concentration. The 50 times dilution of ethyl acetate extract from H. tuberosus leaves was selected for pot test against pepper blight. , and the results showed that its control effect against pepper blight reached 100.00%, superior than that of chemical agent 25% metalaxyl WP 400 times dilution.
基金Supported by International Cooperation Project of Guizhou Science and Technology Department "Analysis of biological characteristics and genetic diversity of Phytophthora capsici isolates from Guizhou Province by RAPD"(QKHWGZ[2013]No.7032)
文摘Ten random primers with clear amplification profile, significant and stable main band were screened from RAPD （Random Amplified Polymorphie DNAs） primers to analyze the genetic diversity among eight Phytophthora capsici isolates from Huaxi District, Wudang District and Kaiyang County of Guiyang City, and Zunyi County, Suiyang County and Luodian County of Zunyi City in Guizhou Province. A total of 70 DNA fingerprints were obtained, including 57 polymorphic bands, with a polymorphic percentage of 81.43%, suggesting abundant genetic diversity among experimental Phytophthora capsici isolates. According to the ampli- fied DNA fingerprint profiles, using genetic similarity coefficient 0.5 as the threshold, experimental Phytophthora capsici isolates were clustered into three genetic categories by UPGMA cluster analysis. The analysis result indicated that there was no direct correlation between the genetic similarity and cultivation areas of vari- ous Phytophthora caosici isolates.
文摘Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phytophthora capsici. Differences in root rot, stem blight and foliar blight severities among accessions were significant. The accessions consistently differentiated into two groups across the three disease syndromes. Simple sequence repeat (SSR) markers showed variability both within and between accessions of California Wonder. The variability in the responses to the three forms of Phytophthora blight does not warrant its usefulness as a standard susceptible control in studies involving the Capsicum-P. capsici patho-system.
基金This work was supported by National Natural Science Fundation of China (No.30400285, 30671317), Postdoctoral Grant from Ag-riculture Sciences Academy of Heilongjiang Province (No. LRB06-010), China Postdoctoral Grant, Item for Teachers from Heilongjiang University (No. 140022), Young People’s Science Fund of Heilongjiang Province (No. QC06C012), 973(No. 2004CB117203-4), the Opening Fund of Key Opening Laboratory of Physiology and Ecology of Crop in Cold Terra of Agriculture Ministry "the Cloning and Mapping of cDNA Sequence from Related Gene Resistant to Phytophthora sojae and International Tech-nology Cooperation Item (No. 2005DFA30340).
文摘The internal transcribed spacer （ITS） region （ITS1, ITS2 and 5.8S rDNA） of the nuclear ribosomal DNA （nrDNA） was amplified via the PCR method in seventeen different isolates of Phytophthora sojae using the common primers of the ITS of fungi. Around 800 bp- 1,000 bp fragments were obtained based on the DL2000 marker and the sequences of the PCR products were tested. Taking isolate USA as outgroup, the phylogenetic tree was constructed by means of maximum parsimony analysis, and the genetic evolution among isolates was analyzed. The results showed that there is a great difference between the base constitution of ITS 1 and ITS2 among various isolates. The seventeen isolates are classified into three groups, and the isolates from the same region belong to the same group, which shows the variation in geography.
文摘A complete cDNA of potato Phytophthora infestans-induced hypersensitive response-related protein gene (POTHR-1) was cloned using rapid amplification of cDNA ends (RACE) strategy according to a fragment sequence which we had cloned using suppression subtractive hybridization (SSH) technique. The potato POTHR-1 gene encodes a protein of 225 amino acids, which shares 81% identity with tobacco hin1 gene-enoded protein (harpin-induced protein). Southern blot revealed that there are two to three copies of POTHR-1 in potato genome. The POTHR-1 gene expression in potato leaves showed that its transcripts accumulated remarkably in leaves after 36 h inoculation with P. infestans. Mechanical wounding and jasmonic acid (JA) could induce the POTHR-1 gene expression and osmotic stress just induce a slight accumulation of POTHR-1 gene mRNA, while salicylic acid (SA) had no detectable function on the induction accumulation of POTHR-1 gene transcripts. The potato POTHR-1 gene may preferentially associate with hypersensitive response (HR) or biotic cell death during interaction between host and pathogen.
基金Supported by Natural Science Foundation of Heibei Province(C2011201003)~~
文摘[ Objective ] The paper was to screen bacterial strain with significant antagonistic effect against Phytophthora infestans, so as to provide basis for further development and utilization of antagonistic bacteria to inhibit P. infestans and control potato late bright. [ Method] Plate dual culture and filter paper method were used to determine the inhibition effect of strains in vivo, fermentation broth and bacterial liquid of 61 strains against P. infestans and the resistance-induction effect of SR13-2 strain. [ Result] The inhibition rate of 24 strains among 61 tested strains against mycelial growth of P. infestans was greater than 60%, and the inhibi- tion effect of HT-6 strain was the strongest with the inhibition rate of 89.92%. However, fermentation broth of all tested strains had no significant inhibition effect against P. infestans, while the inhibition effect of bacterial liquid of most strains was significantly higher than strain in vivo; the inhibition effect of $34-1 strain was the strongest with inhibition rate of 91.50%. The bacterial liquid of SR13-2 strain was found to have significant resistance-induction effect with protective rate of 60%. [ Conclusion] The inhibition effect of strains in vivo and fermentation broth of antagonistic strains S34-1 and SR13-2 had no relationship with each other, while bacterial liquid had great application potential in controlling potato late bright.
