The Salmonella pathogenicity islands(SPIs) play crucial roles in the progression of Salmonella infection. In this study, we constructed an improved λ Red homologous recombination system to prepare single and triple d...The Salmonella pathogenicity islands(SPIs) play crucial roles in the progression of Salmonella infection. In this study, we constructed an improved λ Red homologous recombination system to prepare single and triple deletion mutants of 3 prominent SPIs(SPI-1, 2, and 3), aiming at the impact of deletion on morphology, carbon source metabolism, adhesion and invasion capacity, in vivo colonization, and immune efficacy in chicks. Our examination revealed that the surface of the single deletion mutants(SM6ΔSPI1, ΔSPI2, and ΔSPI3) exhibited a more rugged texture and appeared to be enveloped in a layer of transparent colloid, whereas the morphology of the triple deletion mutant(SM6ΔSPI1&2&3) remained unaltered when compared to the parent strain. The carbon metabolic spectrum of the SPI mutants underwent profound alterations, with a notable and statistically significant modification observed in 30 out of 95 carbon sources, primarily carbohydrates(17 out of 30). Furthermore, the adhesion capacity of the 4 mutants to Caco-2 cells was significantly reduced when compared to that of the parent strain. Moreover,the invasion capacity of mutants SM6ΔSPI1 and SM6ΔSPI1&2&3 exhibited a substantial decrease, while it was enhanced to varying degrees for SM6ΔSPI3 and SM6ΔSPI2. Importantly, none of the 4 mutants induced any clinical symptoms in the chicks. However, they did transiently colonize the spleen and liver. Notably, the SM6ΔSPI1&2&3mutant was rapidly cleared from both the spleen and liver within 8 days post-infection and no notable pathological changes were observed in the organs. Additionally, when challenged, the mutants immunized groups displayed a significant increase in antibody levels and alterations in the CD3+CD4+ and CD3+CD8+ subpopulations, and the levels of IL-4 and IFN-γ cytokines in the SM6ΔSPI1&2&3 immunized chicken serum surpassed those of other groups.In summary, the successful construction of the 4 SPI mutants lays the groundwork for further exploration into the pathogenic(including metabolic) mechanisms of SPIs and the development of safe and effective live attenuated Salmonella vaccines or carriers.展开更多
Coffee wilt represents one of the most devastating diseases of Arabica coffee(Coffea arabica L.)plantations in the primary coffee-producing regions.In this study,coffee trees manifesting wilt symptoms accompanied by t...Coffee wilt represents one of the most devastating diseases of Arabica coffee(Coffea arabica L.)plantations in the primary coffee-producing regions.In this study,coffee trees manifesting wilt symptoms accompanied by the defoliation and drying of the whole tree were observed in the Jazan,El Baha,Najran,and Asir regions.The purpose of this investigation was to isolate and identify the Fusarium species recovered from symptomatic coffee trees.The developed fungi were initially characterized based on their morphological features followed by molecular phylogenetic multi-locus analysis of the combined sequences of ITS,TEF1-α,RPB2,and CaM.Twenty-five isolates were recovered from 28 samples.All fungal isolates were categorized morphologically under the genus Fusarium.Phylogenetic analysis positioned all the representative 15 isolates into one cluster grouping together with Neocosmospora falciformis(formerly F.falciforme)confirming their taxonomic position.Pathogenicity tests of the N.falciformis isolates were subsequently conducted on coffee seedlings,and the results revealed that all isolates induced wilt symptoms resembling those recorded in the field,and the incidence was 100%.The fungicide sensitivity test of seven investigated fungicides revealed that Maxim XL^(®) followed by Moncut^(®) exhibited the highest inhibitory effect against N.falciformis KSA 24-14,reaching 93.33%and 91.67%,respectively.To our knowledge,N.falciformis is a new causal pathogen of coffee wilt in Saudi Arabia.Remarkably,these results offer important insights for devising effective approaches to monitor and control such diseases.展开更多
Magnaporthe oryzae is the causal agent of rice blast. Glycosylation plays key roles in vegetative growth,development, and infection of M. oryzae. However, several glycosylation-related genes have not been characterize...Magnaporthe oryzae is the causal agent of rice blast. Glycosylation plays key roles in vegetative growth,development, and infection of M. oryzae. However, several glycosylation-related genes have not been characterized.In this study, we identified a Glyco_transf_22 domain-containing protein, MoAlg9, and found that MoAlg9 islocalized to the endoplasmic reticulum(ER). Deletion of MoALG9 significantly affected conidial production, normalappressorium formation, responses to stressors, and pathogenicity of M. oryzae. We also found that the ΔMoalg9mutant was defective in glycogen utilization, appressorial penetration, and invasive growth in host cells. Moreover,we further demonstrated that MoALG9 regulates the transcription of several target genes involved in conidiation,appressorium formation, and cell wall integrity. In addition, we found that the Glyco_transf_22 domain is essentialfor normal MoAlg9 function and localization. We also provide evidence that MoAlg9 is involved in N-glycosylationpathway in M. oryzae. Taken together, these results show that MoAlg9 is important for conidiation, appressoriumformation, maintenance of cell wall integrity, and the pathogenesis of M. oryzae.展开更多
Grape white rot caused by Coniella vitis is a global concern in the grape industry.pH regulation is essential for cell growth,reproductive processes and pathogenicity in phytopathogenic fungi.In this study,we observed...Grape white rot caused by Coniella vitis is a global concern in the grape industry.pH regulation is essential for cell growth,reproductive processes and pathogenicity in phytopathogenic fungi.In this study,we observed that the growth rate,spore production and virulence of C.vitis significantly declined in alkaline pH,as well as the suppressive effect on secretion of hydrolytic enzymes.Transcriptomic and metabolomic analyses were used to investigate the responses of C.vitis to acidic(pH 5),neutral(pH 7)and alkaline environments(pH 9).We identified 728,1,780 and 3,386 differentially expressed genes(DEGs)at pH 5,pH 7 and pH 9,when compared with the host pH(pH 3),and 2,122 differently expressed metabolites(DEMs)in negative and positive ion mode.Most DEGs were involved in carbohydrate metabolic process,transmembrane transport,tricarboxylic acid cycle,peptide metabolic process,amide biosynthetic process,and organic acid metabolic process.In addition,metabolomic analysis revealed ABC transporters,indole alkaloid biosynthesis,diterpenoid biosynthesis,and carotenoid biosynthesis pathways in response to the pH change.Furthermore,we found that the aspartate synthesis metabolic route associated with the TCA cycle is a key limiting factor for the growth and development of C.vitis in alkaline environments,and aspartate supplementation enables C.vitis to grow in alkaline environments.Plant cell wall-degrading enzymes(PCWDEs)could contribute to the pathogenicity,when C.vitis infected at pH 3.Importantly,aflatrem biosynthesis in acidic environment might contribute to the virulence of C.vitis and has a risk of causing human health problems due to its acute neurotoxic effects.展开更多
Plant pathogens secrete various cell wall-degrading enzymes that compromise host cell wall integrity and facilitate pathogen invasion.This study identified VdGH7a,a glycoside hydrolase family 7(GH7)cellobiohydrolase f...Plant pathogens secrete various cell wall-degrading enzymes that compromise host cell wall integrity and facilitate pathogen invasion.This study identified VdGH7a,a glycoside hydrolase family 7(GH7)cellobiohydrolase from Verticillium dahliae,which demonstrated hydrolytic activity against 1,4-β-glucan.Notably,VdGH7a induced cell death in Nicotiana benthamiana when signal peptides were present,though this effect was inhibited by the carbohydrate-binding type-1(CBM1)protein domain.The deletion of VdGH7a substantially reduced V.dahliae pathogenicity in cotton plants,as demonstrated by the mutants’inability to penetrate cellophane membrane.These knockout mutants also exhibited reduced carbon source utilization capacity and increased sensitivity to osmotic and cell wall stresses.Through yeast two-hybrid screening,bi-molecular fluorescence complementation(BiFC),and luciferase complementation imaging(LCI),we identified that VdGH7a interacts with an osmotin-like protein(GhOLP1)in cotton.Virus-induced gene silencing of GhOLP1 resulted in decreased salicylic acid(SA)content and reduced resistance to V.dahliae in cotton,while heterologous overexpression of GhOLP1 in Arabidopsis enhanced both resistance and SA signaling pathway gene expression.These results reveal a virulence mechanism wherein the secreted protein VdGH7a from V.dahliae interacts with GhOLP1 to activate host immunity and contribute significantly to plant resistance against V.dahliae.展开更多
In Candida species,the endoplasmic reticulum(ER)stress response—regulated by the unfolded protein response(UPR)—serves as a critical adaptive mechanism affecting both pathogenicity and antifungal resistance.This rev...In Candida species,the endoplasmic reticulum(ER)stress response—regulated by the unfolded protein response(UPR)—serves as a critical adaptive mechanism affecting both pathogenicity and antifungal resistance.This review aims to synthesize current knowledge on ER stress pathways in Candida glabrata and Candida albicans,highlighting their species-specific adaptations and therapeutic implications.We systematically analyzed peer-reviewed literature on ER stress mechanisms in Candida,focusing on comparative studies of UPR signaling.Emphasis was placed on C.glabrata’s inositol-requiring enzyme 1(IRE1)-dependent Regulated IRE1-Dependent Decay(RIDD)pathway and C.albicans’IRE1/HAC1 and calcium-mediated pathways.Connections to virulence and drug resistance were evaluated through genetic,transcriptomic,and phenotypic evidence.Candida species employ divergent UPR strategies:C.glabrata mitigates ER stress primarily via RIDD-mediated mRNA decay to reduce protein load,while C.albicans enhances folding capacity through HAC1 splicing and calcium homeostasis.These adaptations promote survival in hostile host environments(e.g.,oxidative stress,immune attacks)and are linked to resistance against azoles and echinocandins.Pharmacological disruption of UPR components(e.g.,IRE1 inhibitors)sensitizes Candida to antifungals in experimental models.ER stress response pathways are promising targets for antifungal drug development.Understanding species-specific UPR mechanisms in Candida could guide novel therapies to overcome resistance and improve treatment outcomes.展开更多
Background:New variants of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)continue to drive global epidemics and pose significant health risks.The pathogenicity of these variants evolves under immune press...Background:New variants of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)continue to drive global epidemics and pose significant health risks.The pathogenicity of these variants evolves under immune pressure and host factors.Understanding these changes is crucial for epidemic control and variant research.Methods:Human angiotensin-converting enzyme 2(hACE2)transgenic mice were in-tranasally challenged with the original strain WH-09 and the variants Delta,Beta,and Omicron BA.1,while BALB/c mice were challenged with Omicron subvariants BA.5,BF.7,and XBB.1.To compare the pathogenicity differences among variants,we con-ducted a comprehensive analysis that included clinical symptom observation,meas-urement of viral loads in the trachea and lungs,evaluation of pulmonary pathology,analysis of immune cell infiltration,and quantification of cytokine levels.Results:In hACE2 mice,the Beta variant caused significant weight loss,severe lung inflammation,increased inflammatory and chemotactic factor secretion,greater mac-rophage and neutrophil infiltration in the lungs,and higher viral loads with prolonged shedding duration.In contrast,BA.1 showed a significant reduction in pathogenicity.The BA.5,BF.7,and XBB.1 variants were less pathogenic than the WH-09,Beta,and Delta variants when infected in BALB/c mice.This was evidenced by reduced weight loss,diminished pulmonary pathology,decreased secretion of inflammatory factors and chemokines,reduced macrophage and neutrophil infiltration,as well as lower viral loads in both the trachea and lungs.Conclusion:In hACE2 mice,the Omicron variant demonstrated the lowest pathogenic-ity,while the Beta variant exhibited the highest.Pathogenicity of the Delta variant was comparable to the original WH-09 strain.Among BALB/c mice,Omicron subvari-ants BA.5,BF.7,and XBB.1 showed no statistically significant differences in virulence.展开更多
[Objective] This study aimed to investigate the genetic variation of g E gene of an epidemic pseudorabies virus（PRV） strain and its pathogenicity to piglets. [Method] By serial passage in Vero cells, a PRV strain wa...[Objective] This study aimed to investigate the genetic variation of g E gene of an epidemic pseudorabies virus（PRV） strain and its pathogenicity to piglets. [Method] By serial passage in Vero cells, a PRV strain was isolated from the brain tissues of stillborn fetuses delivered by sows with suspected PRV infection and preliminarily identified by PCR. g E gene of the isolated PRV strain was amplified and sequenced for phylogenetic analysis. In addition, the pathogenicity of the isolated PRV strain to 6-week-old piglets was evaluated. [Result] A PRV strain was successfully isolated and named PRV N5 B strain, which could proliferate in Vero cells and TCID50 of the 15 thgeneration virus liquid reached 10^7.125/0.1 ml. Specific bands could be amplified by PCR. g E gene in the isolated PRV strain was 1 740 bp in length. A phylogenetic tree was constructed based on full-length g E sequences, which showed that PRV N5 B strain and PRV strains isolated since 2012 were clustered into the same independent category and shared 99.7%-100% homology of nucleotide sequences. Compared with related sequences published previously, there were insertions of three consecutive bases at two loci. Animal experiments showed that intranasal inoculation of 6-week-old piglets with 2 ml of PRV N5 B strain（10^6/0.1 ml） led to a mortality rate of 100%. [Conclusion] In this study,genetic variability of g E gene in PRV N5 B isolate and its pathogenicity to piglets were analyzed, which provided a theoretical basis for the development of new vaccines to prevent and control porcine pseudorabies.展开更多
[Objective] This study was conducted to investigate the pathogenicity of Plasmodiophora brassicae on cabbage grown under different temperature and soil pH conditions. [Method] The pathogenicity of P. brassicae were te...[Objective] This study was conducted to investigate the pathogenicity of Plasmodiophora brassicae on cabbage grown under different temperature and soil pH conditions. [Method] The pathogenicity of P. brassicae were tested at seven different temperatures and at six different soil pH values with the resting spore concentration of lx108 （spores/g） in the soil. The plant survival rate and incidence rate of clubroot were investigated after 90 d. [Result] The incidence rate of clubroot on cabbage among the different temperature sets varied in a descending order as follows： 30 ℃〉25 ℃〉20 ℃〉35 ℃〉15 ℃〉10 ℃〉5 ℃ at soil pH value of 6, indicating that the pathogenicity of P. brassicae was weak at 5 and 10 ~（3. The incidence rate increased with soil temperature increasing from 15 to 30 ℃, but decreased at 35 ℃. The incidence rates of clubroot were 80.36%, 100%, 65%, 10.77%, 3.23% and 0% at soil pH 4, 5, 6, 7, 8 and 9 at 25 ℃, respectively. The growth of cabbage was inhibited and the survival rate was reduced at pH 4.The incidence rates of clubroot were low at pH value of 7 and 8, and was 0% at pH 9. The Chinese cabbage grew better at pH value of 5 and 6, but had high incidence rates of clubroot. [Conclusion] The results revealed that the incidence rate of clubroot on cabbage was closely related to the temperature and soil pH.展开更多
[Objective] This study was to investigate the relationship between biological characteristics of Beauveria bassiana （Bals.） Vuill and pathogenicity to Bombyx rnori L, with the aim to provide scientific basis for the...[Objective] This study was to investigate the relationship between biological characteristics of Beauveria bassiana （Bals.） Vuill and pathogenicity to Bombyx rnori L, with the aim to provide scientific basis for the control of white muscardine in Bombyx mori L. [Method] The strains isolated and purified from the 6 Beauveria bassiana biocontrol agents from all over the country and the 3 white muscardine silkworms collected from Guangxi provincial silkworm rearing areas were identified by the morphological observation and molecular biology technology. The pathogenicity of B. bassaina to silkworms was determined, and the biological characteristics such as growth diameter, sporulation and the extracellular protease activity of the different B. bassiana strains were compared. [Result] The isolated 9 strains were all B. bassaina （Bals.） Vuillemin, and all strains had high pathogenicity to silkworm, but with different pathogenicities. The growth diameter, sporulation and extracellular protease activity of different B. bassiana strains were also different, and showed correlation with the patheogenicity to silkworms. [Conclusion] B. bassiana spores production amount and exocellular protease activity had significant positive correlation with their pathogenicity to silkworm.展开更多
In order to determine population genetic structure and pathogenicity of Ustilaginoidea virens in the major rice-growing areas of Anhui Province, total 92 U. virens strains were collected from 28 rice-planting counties...In order to determine population genetic structure and pathogenicity of Ustilaginoidea virens in the major rice-growing areas of Anhui Province, total 92 U. virens strains were collected from 28 rice-planting counties （cities） of Anhui Province. Their genetic diversity was analyzed by using REP-PCR （repetitive extragenic palindromic sequence PCR）, and pathogenicity was determined with artificial inoculation method. The results showed that U. virens in rice-growing regions of Anhui Province had a rich genetic diversity. At the similarity level of 0.76, the 92 U. virens strains could be classified into 7 groups. Significant differences were found in pathogenicity among the 24 U. virens strains belonging to different groups, which showed no association with territorial source of U. virens strain or cluster method adopted by this study. Strain pathogenicity and rice varieties showed significant specificity.展开更多
[ Objective] The paper was to study the cultural characteristic of the pathogen of Rice Sheath Blight （ Rhizoctonia solani Kuhn） and its pathogenicity in Sichuan regions. [ Method] The samples of rice sheath blight ...[ Objective] The paper was to study the cultural characteristic of the pathogen of Rice Sheath Blight （ Rhizoctonia solani Kuhn） and its pathogenicity in Sichuan regions. [ Method] The samples of rice sheath blight collected from six main rice planting areas in Sichuan regions were separated. The separated pathogen of rice sheath blight was cultured on PDA medium, and its cultural characteristic was recorded. Meanwhile, the pathogenicity of the obtained 23 strains was determined. [ Result] The growth rates among different strains had significant difference. According to the growth rate, only one strain belonged to medium strain（colony diameter： 40 mm≤（Ф≤60 mm）, the rest were all slow-type strains （colony diam- eter Ф〈40 mm）, and there was no strain with fast growth rate （colony diameter Ф 〉 60 mm）. Pathogenicity test showed that the pathogenicity among strains was significantly different, only one strain had strong pathogenicity, and the others all had moderate or weak pathogenicity. [ Conclu- sion] The study confirmed the basic biological characteristics of the pathogen of rice sheath blight in Sichuan region, which would provide theoretical basis for effective control of rice sheath blight in the region.展开更多
[Objective] In order to find the pathogenic microorganisms suitable for biological control of filth flies, the pathogenic microorganism was isolated from the dead fly, Boettcherisca peregrine. [Method] The conidia and...[Objective] In order to find the pathogenic microorganisms suitable for biological control of filth flies, the pathogenic microorganism was isolated from the dead fly, Boettcherisca peregrine. [Method] The conidia and mycelia were observed by optical microscope. The pathogenic microorganism was identified on the basis of its culture characters and the optical morphologies of the conidia and mycelia, and its biological characteristics and pathogenicity were preliminarily studied. [Result] The pathogenic microorganism isolated from the dead fly was a new strain of Verticillium lecanii. The new strain of V. lecanii was numbered as KMZW-1. The colonies of V. lecanii KMZW-1 grew fastest on potato dextrose agar medium （PDA） at 29 ℃ and pH 6.0. The LC50 of its spore suspension to the adults of B. peregrine, Lucilia sericata, Musca domestic, Piophila casei and Drosophila melanogaster were 9.50×10^5, 4.58×10^7, 4.06×10^7, 4.10×10^3 and 1.05×10^7 conidia/ml, respectively. The LT50 were 6.86, 8.17, 8.16, 8.12 and 3.22 d, respectively. [Conclusion] V. lecanii KMZW-1 is an active pathogenic microorganism to control the adults of five fly species.展开更多
[ Objective ] The paper was to confirrm the effect of hrpZpsg12 gene on the pathogenicity of Pseudomonas syringae pv. glycinea. [ Method ] hrpZpsg12 gene was cloned from P. syringae using PCR method. The knockout plas...[ Objective ] The paper was to confirrm the effect of hrpZpsg12 gene on the pathogenicity of Pseudomonas syringae pv. glycinea. [ Method ] hrpZpsg12 gene was cloned from P. syringae using PCR method. The knockout plasmid pKNOCK-Cm with suicide characteristics and cosmid pUFR034 with complementation func- tion were used to construct the mutation vector pKNOCK477-7 and complementary vector pUFR1026-68 of hrpZpsg12 gene, the mutant 477-1 and the functional com- plementation unit 1026-5 of the gene was also screened out. Three strains including wild-type Psg12, mutant 477-1 and complementary unit 1026-5 were simultane- ously inoculated into soybean leaves and tobacco leaves, then pathogenicity determination and hypersensitive reaction analysis were carried out. [ Result] All the inoculated leaves of soybean and tobacco produced reaction lesion. However, the sizes of reaction lesion were different. The lesion in the leaves inoculated with Psgl2 was relatively large, while the lesion in the leaves inoculated with 477-1 was relatively small; the lesion of complementary unit 1026-5 was similar to wild- type Psgl2. Analysis of reproduction quantity of bacteria in lesions showed that the reproduction quantity of wild-type Psg12 was the highest, while that of mutant 477-1 was the lowest. The reproduction quantity of complementary unit 1026-5 was similar to that of wild-type Psg12. [ Conclusion] hrpZpsg12 gene could enhance the pathogenicity of P. syrimgae on Soybean and produce hypersensitive response in tobacco.展开更多
[Objective] The study was to isolate and identify the pathogen of Pandora neoaphidis and to determine its pathogenicity against turnip aphid （Lipaphis erysimi）.[Method] Based on the morphological characteristics,the...[Objective] The study was to isolate and identify the pathogen of Pandora neoaphidis and to determine its pathogenicity against turnip aphid （Lipaphis erysimi）.[Method] Based on the morphological characteristics,the species of pathogenic fungus was identified.Spore shower method was used to carry out bioassay on the pathogen against turnip aphid.[Result] Primary conidia were ovoid,bitunicate and uninucleate,（24.7±1.4）μm×（10.7±0.9）μm,L/D=2.3±0.2.Secondary conidia had the similar shape with the primary ones,（18.6±2.1）μm×（13.3±1.3）μm,L/D=1.4±0.2.Hyphal body was like mycelium with the diameter of （10.6±0.8）μm.Conidiophores had palmate branch with the diameter of （10.0±0.9）μm.Pseudocystidia was not branched,which had rough base with the diameter of （19.2±1.7）μm,and gradually became more angular towards the apex with the diameter of （8.0±0.9）μm at tips.Rhizoid was like monohyphal shape with the diameter of （21.0±3.0）μm at base,the terminal apex had regular discoid holdfast.No resting spores were observed.The lethal dose of the pathogen against turnip aphid was 18.2/mm2.[Conclusion] The entomopathogenic fungus against turnip aphid was identified to be Pandora neoaphidis,and the pathogen was confirmed to have strong pathogenicity against turnip aphid.展开更多
Biological nature of the bacterial pathogenicity phenomenon is based on the interaction of prokaryotic and eukaryotic organisms. The phenomenon is the poly-functional biological potency of germs that are realized by f...Biological nature of the bacterial pathogenicity phenomenon is based on the interaction of prokaryotic and eukaryotic organisms. The phenomenon is the poly-functional biological potency of germs that are realized by factors (determinants) of pathogenicity. Some fundamental biological functions are responsible for bacterial pathogenicity in a multi-cellular host organism: the adhesive function, the function of invasion and penetration into the cell, the function of evasion of host defense, and the damage function. The action of adhesion, invasion and evasionis directed to towards establishing an ecological niche in multi-cellular host while the aim of the damaging function is destruction of the environment.展开更多
Fowl adenovirus serotype 4(FAdV-4)strain SD1511 was isolated from chickens with severe inclusion body hepatitis and hydropericardium syndrome in Shandong Province,China.The isolate was cultured in primary chicken embr...Fowl adenovirus serotype 4(FAdV-4)strain SD1511 was isolated from chickens with severe inclusion body hepatitis and hydropericardium syndrome in Shandong Province,China.The isolate was cultured in primary chicken embryo kidney cells.A study of pathogenicity indicated that SD1511 readily infected 7–35-d-old chickens by intramuscular injection and intranasal and oral routes,causing 50%–100%mortality.The 35-d-old chickens suffered more severe infection than 7-and 21-d-old chickens with mortality highest in the intramuscular injection group.The serum from surviving chickens showed potent viral neutralizing capability.The complete genome of SD1511 was sequenced and analyzed.The strain was found to belong to the FAdV-4 cluster with more than 99%identity with the virulent FAdV-4 strains isolated in China in recent years except for some distinct variations,including deletions of open reading frame 27(ORF27),ORF48,and part of ORF19.Our findings suggest that SD1511 might be used as a prototype strain for the study of pathogenesis and vaccine development.展开更多
The mitogen-activated protein kinase （MAPK）, a key signal transduction component in the MAPK cascade pathway, regulates a variety of physiological activities in eukaryotes. However, little is known of the role MAPK ...The mitogen-activated protein kinase （MAPK）, a key signal transduction component in the MAPK cascade pathway, regulates a variety of physiological activities in eukaryotes. However, little is known of the role MAPK plays in phytopathogenic fungi. In this research, we cloned the MAPK gene STK1 from the northern corn leaf blight pathogen Setosphaeria turcica and found that the gene shared high homology with the high osmolality glycerol （HOG） MAPK gene HOG1 of Saccharomy- ces cerevisiae. In addition, gene knockout technology was employed to investigate the function of STKI. Gene knockout mutants （KOs） were found to have altered hyphae morphology and no conidiogenesis, though they did show similar radial growth rate compared to the wild-type strain （WT）. Furthermore, microscope observations indicated that STK1 KOs did not form normal appressoria at 48 h post-inoculation on a hydrophobic surface. STK1 KOs had reduced virulence, a significantly altered Helminthosporium turcicum （HT）-toxin composition, and diminished pathogenicity on the leaves of susceptible inbred corn OH43. Mycelium morphology appeared to be significantly swollen and the radial growth rates of STK1 KOs declined in comparison with WT under high osmotic stress. These results suggested that STK1 affects the hyphae development, conidiogenesis, and pathogenicity of S. turcica by regulating appressorium development and HT-toxin biosynthesis. Moreover, the gene appears to be involved in the hypertonic stress response in S. turcica.展开更多
Obligate biotrophic fungi cause serious and widespread diseases of crop plants, but are challenging to investigate because they cannot be cultured in vitro. The two economically important groups of biotrophic fungi pa...Obligate biotrophic fungi cause serious and widespread diseases of crop plants, but are challenging to investigate because they cannot be cultured in vitro. The two economically important groups of biotrophic fungi parasitizing wheat are the rust and powdery mildew pathogens, but their obligate biotrophic lifestyles and pathogenicity mechanisms are not well understood at the molecular level. With the advent of next generation sequencing technology, increasing numbers of pathogen genomes are becoming available. Research in plant pathology has entered a new genomics era. This review summarizes recent progress in understanding the biology and pathogenesis of biotrophic fungal pathogens attacking wheat based on pathogen genomics. We particularly focus on the three wheat rust and the powdery mildew fungi in regard to genome sequencing, avirulence gene cloning, effector discovery, and pathogenomics. We predict that coordinated study of both wheat and its pathogens should reveal new insights in biotrophic adaptation, pathogenicity mechanisms,and population dynamics of these fungi that will assist in development of new strategies for breeding wheat varieties with durable resistance.展开更多
Recently, a new bacterial top rot disease of maize has frequently appeared in many areas of Yunnan Province, China. The pathogen of the disease was identified as Klebsiella pneumoniae （KpC4）, which is well known to ...Recently, a new bacterial top rot disease of maize has frequently appeared in many areas of Yunnan Province, China. The pathogen of the disease was identified as Klebsiella pneumoniae （KpC4）, which is well known to cause pulmonary and urinary diseases in humans and animals and occasionally exists as a harmless endophyte in plants. To evaluate the viru- lence of the maize pathogen to maize and mice, we inoculated maize and mice with routine inoculation and intraperitoneal injection respectively according to Koch＇s postulates. The results showed that KpC4 and the clinical strain K. pneumoniae 138 （Kp138） were all highly pathogenic to maize and mice and the strain re-isolated from diseased mice also caused typical top rot symptoms on maize by artificial inoculation. It is highlighting that a seemingly dedicated human/animal pathogen could cause plant disease. This is the first report of K. pneumoniae, an opportunistic pathogen of human/animal, could infect maize and mice. The findings serve as an alert to plant, medical and veterinarian scientists regarding a potentially dangerous bacterial pathogen infecting both plants and animals/humans. The maize plants in the field could serve as a reservoir for K. pneumoniae which might infect animals and probably humans when conditions are favorable. The new findings not only are significant in the developing control strategy for the new disease in Yunnan, but also serve as a starting point for further studies on the mechanism of pathogenesis and epidemiology of K. pneumoniae.展开更多
基金supported by the National KeyR&DProgramof China(2022YFF0710500)the National Natural Science Foundation of China(32172853 and 32373013)the Central Public-interest Scientific Institution Basal Research Fund,China(1610302022001).
文摘The Salmonella pathogenicity islands(SPIs) play crucial roles in the progression of Salmonella infection. In this study, we constructed an improved λ Red homologous recombination system to prepare single and triple deletion mutants of 3 prominent SPIs(SPI-1, 2, and 3), aiming at the impact of deletion on morphology, carbon source metabolism, adhesion and invasion capacity, in vivo colonization, and immune efficacy in chicks. Our examination revealed that the surface of the single deletion mutants(SM6ΔSPI1, ΔSPI2, and ΔSPI3) exhibited a more rugged texture and appeared to be enveloped in a layer of transparent colloid, whereas the morphology of the triple deletion mutant(SM6ΔSPI1&2&3) remained unaltered when compared to the parent strain. The carbon metabolic spectrum of the SPI mutants underwent profound alterations, with a notable and statistically significant modification observed in 30 out of 95 carbon sources, primarily carbohydrates(17 out of 30). Furthermore, the adhesion capacity of the 4 mutants to Caco-2 cells was significantly reduced when compared to that of the parent strain. Moreover,the invasion capacity of mutants SM6ΔSPI1 and SM6ΔSPI1&2&3 exhibited a substantial decrease, while it was enhanced to varying degrees for SM6ΔSPI3 and SM6ΔSPI2. Importantly, none of the 4 mutants induced any clinical symptoms in the chicks. However, they did transiently colonize the spleen and liver. Notably, the SM6ΔSPI1&2&3mutant was rapidly cleared from both the spleen and liver within 8 days post-infection and no notable pathological changes were observed in the organs. Additionally, when challenged, the mutants immunized groups displayed a significant increase in antibody levels and alterations in the CD3+CD4+ and CD3+CD8+ subpopulations, and the levels of IL-4 and IFN-γ cytokines in the SM6ΔSPI1&2&3 immunized chicken serum surpassed those of other groups.In summary, the successful construction of the 4 SPI mutants lays the groundwork for further exploration into the pathogenic(including metabolic) mechanisms of SPIs and the development of safe and effective live attenuated Salmonella vaccines or carriers.
基金funded by the Deanship of Scientific Research,Vice Presidency for Graduate Studies and Scientific Research,King Faisal University,Saudi Arabia,for supporting this work for work through grant number KFU242134.
文摘Coffee wilt represents one of the most devastating diseases of Arabica coffee(Coffea arabica L.)plantations in the primary coffee-producing regions.In this study,coffee trees manifesting wilt symptoms accompanied by the defoliation and drying of the whole tree were observed in the Jazan,El Baha,Najran,and Asir regions.The purpose of this investigation was to isolate and identify the Fusarium species recovered from symptomatic coffee trees.The developed fungi were initially characterized based on their morphological features followed by molecular phylogenetic multi-locus analysis of the combined sequences of ITS,TEF1-α,RPB2,and CaM.Twenty-five isolates were recovered from 28 samples.All fungal isolates were categorized morphologically under the genus Fusarium.Phylogenetic analysis positioned all the representative 15 isolates into one cluster grouping together with Neocosmospora falciformis(formerly F.falciforme)confirming their taxonomic position.Pathogenicity tests of the N.falciformis isolates were subsequently conducted on coffee seedlings,and the results revealed that all isolates induced wilt symptoms resembling those recorded in the field,and the incidence was 100%.The fungicide sensitivity test of seven investigated fungicides revealed that Maxim XL^(®) followed by Moncut^(®) exhibited the highest inhibitory effect against N.falciformis KSA 24-14,reaching 93.33%and 91.67%,respectively.To our knowledge,N.falciformis is a new causal pathogen of coffee wilt in Saudi Arabia.Remarkably,these results offer important insights for devising effective approaches to monitor and control such diseases.
基金supported by the National Natural Science Foundation of China (32202253)the Natural Science Foundation of Anhui Higher Education Institutions, China (KJ2020A0102)the Talent Research Project of Anhui Agricultural University, China (rc342001)。
文摘Magnaporthe oryzae is the causal agent of rice blast. Glycosylation plays key roles in vegetative growth,development, and infection of M. oryzae. However, several glycosylation-related genes have not been characterized.In this study, we identified a Glyco_transf_22 domain-containing protein, MoAlg9, and found that MoAlg9 islocalized to the endoplasmic reticulum(ER). Deletion of MoALG9 significantly affected conidial production, normalappressorium formation, responses to stressors, and pathogenicity of M. oryzae. We also found that the ΔMoalg9mutant was defective in glycogen utilization, appressorial penetration, and invasive growth in host cells. Moreover,we further demonstrated that MoALG9 regulates the transcription of several target genes involved in conidiation,appressorium formation, and cell wall integrity. In addition, we found that the Glyco_transf_22 domain is essentialfor normal MoAlg9 function and localization. We also provide evidence that MoAlg9 is involved in N-glycosylationpathway in M. oryzae. Taken together, these results show that MoAlg9 is important for conidiation, appressoriumformation, maintenance of cell wall integrity, and the pathogenesis of M. oryzae.
基金supported by the Shandong Provincial Natural Science Foundation,China(ZR2021QC131)the Shandong Province Key Research and Development Plan,China(2022TZXD001102)+1 种基金the Shandong Province Demonstration Project for Model Construction in Rural Revitalization Service,China(2022DXAL0226)the Innovation Project of Shandong Academy of Agricultural Sciences,China(CXGC2023F15,CXGC2023A41,and CXGC2023A47)。
文摘Grape white rot caused by Coniella vitis is a global concern in the grape industry.pH regulation is essential for cell growth,reproductive processes and pathogenicity in phytopathogenic fungi.In this study,we observed that the growth rate,spore production and virulence of C.vitis significantly declined in alkaline pH,as well as the suppressive effect on secretion of hydrolytic enzymes.Transcriptomic and metabolomic analyses were used to investigate the responses of C.vitis to acidic(pH 5),neutral(pH 7)and alkaline environments(pH 9).We identified 728,1,780 and 3,386 differentially expressed genes(DEGs)at pH 5,pH 7 and pH 9,when compared with the host pH(pH 3),and 2,122 differently expressed metabolites(DEMs)in negative and positive ion mode.Most DEGs were involved in carbohydrate metabolic process,transmembrane transport,tricarboxylic acid cycle,peptide metabolic process,amide biosynthetic process,and organic acid metabolic process.In addition,metabolomic analysis revealed ABC transporters,indole alkaloid biosynthesis,diterpenoid biosynthesis,and carotenoid biosynthesis pathways in response to the pH change.Furthermore,we found that the aspartate synthesis metabolic route associated with the TCA cycle is a key limiting factor for the growth and development of C.vitis in alkaline environments,and aspartate supplementation enables C.vitis to grow in alkaline environments.Plant cell wall-degrading enzymes(PCWDEs)could contribute to the pathogenicity,when C.vitis infected at pH 3.Importantly,aflatrem biosynthesis in acidic environment might contribute to the virulence of C.vitis and has a risk of causing human health problems due to its acute neurotoxic effects.
基金supported by the Project of Sanya Yazhou Bay Science and Technology City,China(SCKJ-JYRC-2022-75)the Natural Science Foundation of Hainan Province,China(322QN398).
文摘Plant pathogens secrete various cell wall-degrading enzymes that compromise host cell wall integrity and facilitate pathogen invasion.This study identified VdGH7a,a glycoside hydrolase family 7(GH7)cellobiohydrolase from Verticillium dahliae,which demonstrated hydrolytic activity against 1,4-β-glucan.Notably,VdGH7a induced cell death in Nicotiana benthamiana when signal peptides were present,though this effect was inhibited by the carbohydrate-binding type-1(CBM1)protein domain.The deletion of VdGH7a substantially reduced V.dahliae pathogenicity in cotton plants,as demonstrated by the mutants’inability to penetrate cellophane membrane.These knockout mutants also exhibited reduced carbon source utilization capacity and increased sensitivity to osmotic and cell wall stresses.Through yeast two-hybrid screening,bi-molecular fluorescence complementation(BiFC),and luciferase complementation imaging(LCI),we identified that VdGH7a interacts with an osmotin-like protein(GhOLP1)in cotton.Virus-induced gene silencing of GhOLP1 resulted in decreased salicylic acid(SA)content and reduced resistance to V.dahliae in cotton,while heterologous overexpression of GhOLP1 in Arabidopsis enhanced both resistance and SA signaling pathway gene expression.These results reveal a virulence mechanism wherein the secreted protein VdGH7a from V.dahliae interacts with GhOLP1 to activate host immunity and contribute significantly to plant resistance against V.dahliae.
文摘In Candida species,the endoplasmic reticulum(ER)stress response—regulated by the unfolded protein response(UPR)—serves as a critical adaptive mechanism affecting both pathogenicity and antifungal resistance.This review aims to synthesize current knowledge on ER stress pathways in Candida glabrata and Candida albicans,highlighting their species-specific adaptations and therapeutic implications.We systematically analyzed peer-reviewed literature on ER stress mechanisms in Candida,focusing on comparative studies of UPR signaling.Emphasis was placed on C.glabrata’s inositol-requiring enzyme 1(IRE1)-dependent Regulated IRE1-Dependent Decay(RIDD)pathway and C.albicans’IRE1/HAC1 and calcium-mediated pathways.Connections to virulence and drug resistance were evaluated through genetic,transcriptomic,and phenotypic evidence.Candida species employ divergent UPR strategies:C.glabrata mitigates ER stress primarily via RIDD-mediated mRNA decay to reduce protein load,while C.albicans enhances folding capacity through HAC1 splicing and calcium homeostasis.These adaptations promote survival in hostile host environments(e.g.,oxidative stress,immune attacks)and are linked to resistance against azoles and echinocandins.Pharmacological disruption of UPR components(e.g.,IRE1 inhibitors)sensitizes Candida to antifungals in experimental models.ER stress response pathways are promising targets for antifungal drug development.Understanding species-specific UPR mechanisms in Candida could guide novel therapies to overcome resistance and improve treatment outcomes.
基金National Science and Technology Infrastructure of China,Grant/Award Number:National Pathogen Resource Center-NPRC-32National Key Research and Development Program of China,Grant/Award Number:2023YFF0724800CAMS Innovation Fund for Medical Sciences,Grant/Award Number:2021-I2M-1-035。
文摘Background:New variants of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)continue to drive global epidemics and pose significant health risks.The pathogenicity of these variants evolves under immune pressure and host factors.Understanding these changes is crucial for epidemic control and variant research.Methods:Human angiotensin-converting enzyme 2(hACE2)transgenic mice were in-tranasally challenged with the original strain WH-09 and the variants Delta,Beta,and Omicron BA.1,while BALB/c mice were challenged with Omicron subvariants BA.5,BF.7,and XBB.1.To compare the pathogenicity differences among variants,we con-ducted a comprehensive analysis that included clinical symptom observation,meas-urement of viral loads in the trachea and lungs,evaluation of pulmonary pathology,analysis of immune cell infiltration,and quantification of cytokine levels.Results:In hACE2 mice,the Beta variant caused significant weight loss,severe lung inflammation,increased inflammatory and chemotactic factor secretion,greater mac-rophage and neutrophil infiltration in the lungs,and higher viral loads with prolonged shedding duration.In contrast,BA.1 showed a significant reduction in pathogenicity.The BA.5,BF.7,and XBB.1 variants were less pathogenic than the WH-09,Beta,and Delta variants when infected in BALB/c mice.This was evidenced by reduced weight loss,diminished pulmonary pathology,decreased secretion of inflammatory factors and chemokines,reduced macrophage and neutrophil infiltration,as well as lower viral loads in both the trachea and lungs.Conclusion:In hACE2 mice,the Omicron variant demonstrated the lowest pathogenic-ity,while the Beta variant exhibited the highest.Pathogenicity of the Delta variant was comparable to the original WH-09 strain.Among BALB/c mice,Omicron subvari-ants BA.5,BF.7,and XBB.1 showed no statistically significant differences in virulence.
基金Supported by Natural Science Foundation of Jiangsu Province(BK20131334)Fund for Independent Innovation of Agricultural Science and Technology in Jiangsu Province[CX(13)3069]~~
文摘[Objective] This study aimed to investigate the genetic variation of g E gene of an epidemic pseudorabies virus（PRV） strain and its pathogenicity to piglets. [Method] By serial passage in Vero cells, a PRV strain was isolated from the brain tissues of stillborn fetuses delivered by sows with suspected PRV infection and preliminarily identified by PCR. g E gene of the isolated PRV strain was amplified and sequenced for phylogenetic analysis. In addition, the pathogenicity of the isolated PRV strain to 6-week-old piglets was evaluated. [Result] A PRV strain was successfully isolated and named PRV N5 B strain, which could proliferate in Vero cells and TCID50 of the 15 thgeneration virus liquid reached 10^7.125/0.1 ml. Specific bands could be amplified by PCR. g E gene in the isolated PRV strain was 1 740 bp in length. A phylogenetic tree was constructed based on full-length g E sequences, which showed that PRV N5 B strain and PRV strains isolated since 2012 were clustered into the same independent category and shared 99.7%-100% homology of nucleotide sequences. Compared with related sequences published previously, there were insertions of three consecutive bases at two loci. Animal experiments showed that intranasal inoculation of 6-week-old piglets with 2 ml of PRV N5 B strain（10^6/0.1 ml） led to a mortality rate of 100%. [Conclusion] In this study,genetic variability of g E gene in PRV N5 B isolate and its pathogenicity to piglets were analyzed, which provided a theoretical basis for the development of new vaccines to prevent and control porcine pseudorabies.
基金Supported by Science and Technology Project of Yunnan Province(2014RA061)Special Fund for Modern Agriculture Research System for Rape of Yunnan Province~~
文摘[Objective] This study was conducted to investigate the pathogenicity of Plasmodiophora brassicae on cabbage grown under different temperature and soil pH conditions. [Method] The pathogenicity of P. brassicae were tested at seven different temperatures and at six different soil pH values with the resting spore concentration of lx108 （spores/g） in the soil. The plant survival rate and incidence rate of clubroot were investigated after 90 d. [Result] The incidence rate of clubroot on cabbage among the different temperature sets varied in a descending order as follows： 30 ℃〉25 ℃〉20 ℃〉35 ℃〉15 ℃〉10 ℃〉5 ℃ at soil pH value of 6, indicating that the pathogenicity of P. brassicae was weak at 5 and 10 ~（3. The incidence rate increased with soil temperature increasing from 15 to 30 ℃, but decreased at 35 ℃. The incidence rates of clubroot were 80.36%, 100%, 65%, 10.77%, 3.23% and 0% at soil pH 4, 5, 6, 7, 8 and 9 at 25 ℃, respectively. The growth of cabbage was inhibited and the survival rate was reduced at pH 4.The incidence rates of clubroot were low at pH value of 7 and 8, and was 0% at pH 9. The Chinese cabbage grew better at pH value of 5 and 6, but had high incidence rates of clubroot. [Conclusion] The results revealed that the incidence rate of clubroot on cabbage was closely related to the temperature and soil pH.
基金Supported by the Scientific Research and Technology Development Planning Program of Guangxi Province(10169-08)the Program for the Construction of Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection(Guikeneng1001Z014)~~
文摘[Objective] This study was to investigate the relationship between biological characteristics of Beauveria bassiana （Bals.） Vuill and pathogenicity to Bombyx rnori L, with the aim to provide scientific basis for the control of white muscardine in Bombyx mori L. [Method] The strains isolated and purified from the 6 Beauveria bassiana biocontrol agents from all over the country and the 3 white muscardine silkworms collected from Guangxi provincial silkworm rearing areas were identified by the morphological observation and molecular biology technology. The pathogenicity of B. bassaina to silkworms was determined, and the biological characteristics such as growth diameter, sporulation and the extracellular protease activity of the different B. bassiana strains were compared. [Result] The isolated 9 strains were all B. bassaina （Bals.） Vuillemin, and all strains had high pathogenicity to silkworm, but with different pathogenicities. The growth diameter, sporulation and extracellular protease activity of different B. bassiana strains were also different, and showed correlation with the patheogenicity to silkworms. [Conclusion] B. bassiana spores production amount and exocellular protease activity had significant positive correlation with their pathogenicity to silkworm.
基金Supported by Agricultural Science and Technology Innovation Fund of Anhui Province(14B1148)Special Fund for Talent Development in Anhui Province(13C1109)Science and Technology Major Project of Anhui Province(15CZZ03132)~~
文摘In order to determine population genetic structure and pathogenicity of Ustilaginoidea virens in the major rice-growing areas of Anhui Province, total 92 U. virens strains were collected from 28 rice-planting counties （cities） of Anhui Province. Their genetic diversity was analyzed by using REP-PCR （repetitive extragenic palindromic sequence PCR）, and pathogenicity was determined with artificial inoculation method. The results showed that U. virens in rice-growing regions of Anhui Province had a rich genetic diversity. At the similarity level of 0.76, the 92 U. virens strains could be classified into 7 groups. Significant differences were found in pathogenicity among the 24 U. virens strains belonging to different groups, which showed no association with territorial source of U. virens strain or cluster method adopted by this study. Strain pathogenicity and rice varieties showed significant specificity.
基金Supported by Public Service Sector (Agriculture) Projects (nyhyzx07-049)~~
文摘[ Objective] The paper was to study the cultural characteristic of the pathogen of Rice Sheath Blight （ Rhizoctonia solani Kuhn） and its pathogenicity in Sichuan regions. [ Method] The samples of rice sheath blight collected from six main rice planting areas in Sichuan regions were separated. The separated pathogen of rice sheath blight was cultured on PDA medium, and its cultural characteristic was recorded. Meanwhile, the pathogenicity of the obtained 23 strains was determined. [ Result] The growth rates among different strains had significant difference. According to the growth rate, only one strain belonged to medium strain（colony diameter： 40 mm≤（Ф≤60 mm）, the rest were all slow-type strains （colony diam- eter Ф〈40 mm）, and there was no strain with fast growth rate （colony diameter Ф 〉 60 mm）. Pathogenicity test showed that the pathogenicity among strains was significantly different, only one strain had strong pathogenicity, and the others all had moderate or weak pathogenicity. [ Conclu- sion] The study confirmed the basic biological characteristics of the pathogen of rice sheath blight in Sichuan region, which would provide theoretical basis for effective control of rice sheath blight in the region.
基金Supported by Yunnan Provincial Department of Education,Fund Projects of Young Teachers(06y15SB)Yunnan Science and Technology Project(2006NG16)~~
文摘[Objective] In order to find the pathogenic microorganisms suitable for biological control of filth flies, the pathogenic microorganism was isolated from the dead fly, Boettcherisca peregrine. [Method] The conidia and mycelia were observed by optical microscope. The pathogenic microorganism was identified on the basis of its culture characters and the optical morphologies of the conidia and mycelia, and its biological characteristics and pathogenicity were preliminarily studied. [Result] The pathogenic microorganism isolated from the dead fly was a new strain of Verticillium lecanii. The new strain of V. lecanii was numbered as KMZW-1. The colonies of V. lecanii KMZW-1 grew fastest on potato dextrose agar medium （PDA） at 29 ℃ and pH 6.0. The LC50 of its spore suspension to the adults of B. peregrine, Lucilia sericata, Musca domestic, Piophila casei and Drosophila melanogaster were 9.50×10^5, 4.58×10^7, 4.06×10^7, 4.10×10^3 and 1.05×10^7 conidia/ml, respectively. The LT50 were 6.86, 8.17, 8.16, 8.12 and 3.22 d, respectively. [Conclusion] V. lecanii KMZW-1 is an active pathogenic microorganism to control the adults of five fly species.
基金Supported by Scientific Research Foundation Project of Jilin Agricultural University" hrpZ Psg12 Protein Function of Pseudomonas syringae pv.glycinea" (384)Major Project of Cultivation of Genetically Modified Biological New Varieties of "Eleventh Five-Year Plan" of Ministry of Agriculture"Cultivation of New Transgenic Varieties of Soybean with Diseases and Pests Resistance"(2008ZX08004-004)~~
文摘[ Objective ] The paper was to confirrm the effect of hrpZpsg12 gene on the pathogenicity of Pseudomonas syringae pv. glycinea. [ Method ] hrpZpsg12 gene was cloned from P. syringae using PCR method. The knockout plasmid pKNOCK-Cm with suicide characteristics and cosmid pUFR034 with complementation func- tion were used to construct the mutation vector pKNOCK477-7 and complementary vector pUFR1026-68 of hrpZpsg12 gene, the mutant 477-1 and the functional com- plementation unit 1026-5 of the gene was also screened out. Three strains including wild-type Psg12, mutant 477-1 and complementary unit 1026-5 were simultane- ously inoculated into soybean leaves and tobacco leaves, then pathogenicity determination and hypersensitive reaction analysis were carried out. [ Result] All the inoculated leaves of soybean and tobacco produced reaction lesion. However, the sizes of reaction lesion were different. The lesion in the leaves inoculated with Psgl2 was relatively large, while the lesion in the leaves inoculated with 477-1 was relatively small; the lesion of complementary unit 1026-5 was similar to wild- type Psgl2. Analysis of reproduction quantity of bacteria in lesions showed that the reproduction quantity of wild-type Psg12 was the highest, while that of mutant 477-1 was the lowest. The reproduction quantity of complementary unit 1026-5 was similar to that of wild-type Psg12. [ Conclusion] hrpZpsg12 gene could enhance the pathogenicity of P. syrimgae on Soybean and produce hypersensitive response in tobacco.
基金Supported by Key Projects in Shaoguang Institute (200402)~~
文摘[Objective] The study was to isolate and identify the pathogen of Pandora neoaphidis and to determine its pathogenicity against turnip aphid （Lipaphis erysimi）.[Method] Based on the morphological characteristics,the species of pathogenic fungus was identified.Spore shower method was used to carry out bioassay on the pathogen against turnip aphid.[Result] Primary conidia were ovoid,bitunicate and uninucleate,（24.7±1.4）μm×（10.7±0.9）μm,L/D=2.3±0.2.Secondary conidia had the similar shape with the primary ones,（18.6±2.1）μm×（13.3±1.3）μm,L/D=1.4±0.2.Hyphal body was like mycelium with the diameter of （10.6±0.8）μm.Conidiophores had palmate branch with the diameter of （10.0±0.9）μm.Pseudocystidia was not branched,which had rough base with the diameter of （19.2±1.7）μm,and gradually became more angular towards the apex with the diameter of （8.0±0.9）μm at tips.Rhizoid was like monohyphal shape with the diameter of （21.0±3.0）μm at base,the terminal apex had regular discoid holdfast.No resting spores were observed.The lethal dose of the pathogen against turnip aphid was 18.2/mm2.[Conclusion] The entomopathogenic fungus against turnip aphid was identified to be Pandora neoaphidis,and the pathogen was confirmed to have strong pathogenicity against turnip aphid.
文摘Biological nature of the bacterial pathogenicity phenomenon is based on the interaction of prokaryotic and eukaryotic organisms. The phenomenon is the poly-functional biological potency of germs that are realized by factors (determinants) of pathogenicity. Some fundamental biological functions are responsible for bacterial pathogenicity in a multi-cellular host organism: the adhesive function, the function of invasion and penetration into the cell, the function of evasion of host defense, and the damage function. The action of adhesion, invasion and evasionis directed to towards establishing an ecological niche in multi-cellular host while the aim of the damaging function is destruction of the environment.
基金the National Key Technology Research and Development Program of China(No.2015BAD12B01)the China Agriculture Research System(No.CARS-40-K13)
文摘Fowl adenovirus serotype 4(FAdV-4)strain SD1511 was isolated from chickens with severe inclusion body hepatitis and hydropericardium syndrome in Shandong Province,China.The isolate was cultured in primary chicken embryo kidney cells.A study of pathogenicity indicated that SD1511 readily infected 7–35-d-old chickens by intramuscular injection and intranasal and oral routes,causing 50%–100%mortality.The 35-d-old chickens suffered more severe infection than 7-and 21-d-old chickens with mortality highest in the intramuscular injection group.The serum from surviving chickens showed potent viral neutralizing capability.The complete genome of SD1511 was sequenced and analyzed.The strain was found to belong to the FAdV-4 cluster with more than 99%identity with the virulent FAdV-4 strains isolated in China in recent years except for some distinct variations,including deletions of open reading frame 27(ORF27),ORF48,and part of ORF19.Our findings suggest that SD1511 might be used as a prototype strain for the study of pathogenesis and vaccine development.
基金supported by the National Natural Science Foundation of China (31171805 and 31371897)
文摘The mitogen-activated protein kinase （MAPK）, a key signal transduction component in the MAPK cascade pathway, regulates a variety of physiological activities in eukaryotes. However, little is known of the role MAPK plays in phytopathogenic fungi. In this research, we cloned the MAPK gene STK1 from the northern corn leaf blight pathogen Setosphaeria turcica and found that the gene shared high homology with the high osmolality glycerol （HOG） MAPK gene HOG1 of Saccharomy- ces cerevisiae. In addition, gene knockout technology was employed to investigate the function of STKI. Gene knockout mutants （KOs） were found to have altered hyphae morphology and no conidiogenesis, though they did show similar radial growth rate compared to the wild-type strain （WT）. Furthermore, microscope observations indicated that STK1 KOs did not form normal appressoria at 48 h post-inoculation on a hydrophobic surface. STK1 KOs had reduced virulence, a significantly altered Helminthosporium turcicum （HT）-toxin composition, and diminished pathogenicity on the leaves of susceptible inbred corn OH43. Mycelium morphology appeared to be significantly swollen and the radial growth rates of STK1 KOs declined in comparison with WT under high osmotic stress. These results suggested that STK1 affects the hyphae development, conidiogenesis, and pathogenicity of S. turcica by regulating appressorium development and HT-toxin biosynthesis. Moreover, the gene appears to be involved in the hypertonic stress response in S. turcica.
基金supported by the National Basic Research Program of China (2013CB127700)National Natural ScienceFoundation of China (31371882, 31401693)the 111 Project of the Ministry of Education of China (B07049)
文摘Obligate biotrophic fungi cause serious and widespread diseases of crop plants, but are challenging to investigate because they cannot be cultured in vitro. The two economically important groups of biotrophic fungi parasitizing wheat are the rust and powdery mildew pathogens, but their obligate biotrophic lifestyles and pathogenicity mechanisms are not well understood at the molecular level. With the advent of next generation sequencing technology, increasing numbers of pathogen genomes are becoming available. Research in plant pathology has entered a new genomics era. This review summarizes recent progress in understanding the biology and pathogenesis of biotrophic fungal pathogens attacking wheat based on pathogen genomics. We particularly focus on the three wheat rust and the powdery mildew fungi in regard to genome sequencing, avirulence gene cloning, effector discovery, and pathogenomics. We predict that coordinated study of both wheat and its pathogens should reveal new insights in biotrophic adaptation, pathogenicity mechanisms,and population dynamics of these fungi that will assist in development of new strategies for breeding wheat varieties with durable resistance.
基金funded by the Maize Production System of Yunnan Province,China(2015KJTX002)
文摘Recently, a new bacterial top rot disease of maize has frequently appeared in many areas of Yunnan Province, China. The pathogen of the disease was identified as Klebsiella pneumoniae （KpC4）, which is well known to cause pulmonary and urinary diseases in humans and animals and occasionally exists as a harmless endophyte in plants. To evaluate the viru- lence of the maize pathogen to maize and mice, we inoculated maize and mice with routine inoculation and intraperitoneal injection respectively according to Koch＇s postulates. The results showed that KpC4 and the clinical strain K. pneumoniae 138 （Kp138） were all highly pathogenic to maize and mice and the strain re-isolated from diseased mice also caused typical top rot symptoms on maize by artificial inoculation. It is highlighting that a seemingly dedicated human/animal pathogen could cause plant disease. This is the first report of K. pneumoniae, an opportunistic pathogen of human/animal, could infect maize and mice. The findings serve as an alert to plant, medical and veterinarian scientists regarding a potentially dangerous bacterial pathogen infecting both plants and animals/humans. The maize plants in the field could serve as a reservoir for K. pneumoniae which might infect animals and probably humans when conditions are favorable. The new findings not only are significant in the developing control strategy for the new disease in Yunnan, but also serve as a starting point for further studies on the mechanism of pathogenesis and epidemiology of K. pneumoniae.
