Horizontal gene transfer(HGT)has been proved a major driving force in prokaryotic evolution.However,the molecular functions of these transferred genes in pathogenic bacteria especially plant pathogenic bacteria are st...Horizontal gene transfer(HGT)has been proved a major driving force in prokaryotic evolution.However,the molecular functions of these transferred genes in pathogenic bacteria especially plant pathogenic bacteria are still not fully investigated.In this study,the whole-genome in silico analysis was performed and found a syringopeptin synthetase(syp)homolog in Burkholderia glumae,which can cause bacterial panicle blight in rice,was predicted to be horizontally transferred from Pseudomonas ancestor with solid confidence by phylogenetic analysis.The comprehensive molecular experiments were performed to study the potential role of this gene in B.glumae.Inoculation of rice panicles with the syp mutant resulted in 60%lower disease index compared with the wild type(WT)parent strain,suggesting the requirement of syp for the full virulence of B.glumae.Chromatography analysis of exudates from B.glumae showed suppression of synthesis of metabolites analogous to syringopeptin in the mutants.All these data raise the possibility of HGT phenomenon in shaping the virulence and adaptation of B.glumae over evolutionary time.展开更多
MicroRNA-based gene silencing is a functional genomics tool for a wide range of eukaryotes. As a basis for broader application of virus-induced gene silencing (VIGS) to photosynthesis research, we employed a tobacco r...MicroRNA-based gene silencing is a functional genomics tool for a wide range of eukaryotes. As a basis for broader application of virus-induced gene silencing (VIGS) to photosynthesis research, we employed a tobacco rattle virus (TRV) vector to silence expression of the nuclear psbS gene in Nicotiana benthamiana. The 22-kiloDalton psbS protein is essential for xanthophyll- and H+-dependent thermal dissipation of excitation in higher plants widely known as nonphotochemical quenching (NPQ). Controls treated with the TRV-VIGS vector containing a bacterial chloramphenicol resistance gene as the silencing target were included to test for non-silencing effects of the viral vector system. PsbS protein was undetectable and both psbS mRNA transcript levels and NPQ capacity were dramatically reduced in new leaf tissue of VIGS-psbS plants only. Photosynthetic performance in TRV-VIGS-treated and uninfiltrated plants was assessed by application of CO2 exchange, chlorophyll fluorescence, and in vivo absorbance changes at 810 nm. TRV-VIGS caused a mild stress based on pigment content and light absorption characteristics in some cases. To assess transient complementation of NPQ, the endogenous psbS gene was silenced using only the transit sequence in the TRV vector followed by Agrobacterium-mediated transient expression of a modified gene consisting of an altered transit sequence fused to the native mature protein sequence. Nevertheless, NPQ in infused fully expanded leaves that expressed this re-introduced form was not fully restored indicating the possible importance of psbS incorporation prior to formation of grana stacks.展开更多
Worldwide, wild birds play a vital role in the dispersal of ticks that harbour tick-borne pathogens, including Borrelia burgdorferi, the Lyme disease bacterium. Using PCR testing, we found 124 (31%) of 405 ticks (4 sp...Worldwide, wild birds play a vital role in the dispersal of ticks that harbour tick-borne pathogens, including Borrelia burgdorferi, the Lyme disease bacterium. Using PCR testing, we found 124 (31%) of 405 ticks (4 species), which were collected from 21 species of birds in far-western Canada, to be infected with B. burgdorferi. Transstadial transmission of B. burgdorferi occurred from larva to nymph, plus nymph to adult, in the avian coastal tick, Ixodes auritulus, collected from songbirds in British Columbia (B.C). Collectively, all 3 motile life stages (larva, nymph, adult) of this tick had an infection prevalence of 31% for B. burgdorferi, which suggests vector competency. A Pacific Wren was highly infested with I. auritulus immatures, and 20 (44%) of 45 ticks (2 nymphs, 43 larvae) were infected with B. burgdorferi. This heavy infestation shows the high potential to initiate a new population of ticks and to disseminate Lyme spirochetes. Epidemiologically, B. burgdorferi-infected I. auritulus larvae collected from the Spotted Towhee, Swainson’s Thrush, Pacific Wren, and Fox Sparrow suggest that these avian hosts act as reservoirs for B. burgdorferi. In this study, the western blacklegged tick, Ixodes pacificus, and Ixodes spinipalpis played a limited role in the enzootic transmission cycle of B. burgdorferi along coastal B.C. We document the first record of I. spinipalpis on a bird in Alberta. Because songbirds widely disperse Lyme disease vector ticks, primary health providers and the general public must be vigilant that outdoors people may be bitten by B. burgdorferi-infected ticks throughout far-western Canada.展开更多
Stachybotrys(asexual Hypocreales)has a worldwide distribution.This genus inhabits substrates rich in cellulose and is closely related to Memnoniella.Classification of species has previously been based on morphology,wi...Stachybotrys(asexual Hypocreales)has a worldwide distribution.This genus inhabits substrates rich in cellulose and is closely related to Memnoniella.Classification of species has previously been based on morphology,with conidial characters being considered as important.This study reevaluates Stachybotrys and Memnoniella,which is shown to include at least seven species-groups;while Memnoniella is a synonym of Stachybotrys.The sexual genera Ornatispora and Melanopsamma are also synonyms of Stachybotrys.With the exception of Stachybotrys subsimplex,species formed a wellsupported monophyletic group in LSU data analysis belonging to Stachybotriaceae.Seventy-four accepted Stachybotrys species are discussed,while eight species are considered to belong to other genera or are doubtful in this paper and a key to these species provided.Twelve new combinations and 1 nomina nova is proposed.The status of Stachybotrys species on health,as human or animal pathogens,in indoor environments,and use as biocontrol agents and compound discovery are also discussed.展开更多
基金the National Key R&D Program of China(2018YFD0201202 and 2017YFD0201108)the Agri-X Interdisciplinary Fund of Shanghai Jiao Tong University,China(Agri-X2017010)+3 种基金the State Key Laboratory for Biology of Plant Diseases and Insect Pests of Shanghai Jiao Tong University(SKLOF201802)the Shanghai Committee of Science and Technology(19390743300)the National Natural Science Foundation of China(31200003 and 31770772)Joint Research Funds for Translational Medicine at Shanghai Jiao Tong University(ZH2018ZDA06).
文摘Horizontal gene transfer(HGT)has been proved a major driving force in prokaryotic evolution.However,the molecular functions of these transferred genes in pathogenic bacteria especially plant pathogenic bacteria are still not fully investigated.In this study,the whole-genome in silico analysis was performed and found a syringopeptin synthetase(syp)homolog in Burkholderia glumae,which can cause bacterial panicle blight in rice,was predicted to be horizontally transferred from Pseudomonas ancestor with solid confidence by phylogenetic analysis.The comprehensive molecular experiments were performed to study the potential role of this gene in B.glumae.Inoculation of rice panicles with the syp mutant resulted in 60%lower disease index compared with the wild type(WT)parent strain,suggesting the requirement of syp for the full virulence of B.glumae.Chromatography analysis of exudates from B.glumae showed suppression of synthesis of metabolites analogous to syringopeptin in the mutants.All these data raise the possibility of HGT phenomenon in shaping the virulence and adaptation of B.glumae over evolutionary time.
文摘MicroRNA-based gene silencing is a functional genomics tool for a wide range of eukaryotes. As a basis for broader application of virus-induced gene silencing (VIGS) to photosynthesis research, we employed a tobacco rattle virus (TRV) vector to silence expression of the nuclear psbS gene in Nicotiana benthamiana. The 22-kiloDalton psbS protein is essential for xanthophyll- and H+-dependent thermal dissipation of excitation in higher plants widely known as nonphotochemical quenching (NPQ). Controls treated with the TRV-VIGS vector containing a bacterial chloramphenicol resistance gene as the silencing target were included to test for non-silencing effects of the viral vector system. PsbS protein was undetectable and both psbS mRNA transcript levels and NPQ capacity were dramatically reduced in new leaf tissue of VIGS-psbS plants only. Photosynthetic performance in TRV-VIGS-treated and uninfiltrated plants was assessed by application of CO2 exchange, chlorophyll fluorescence, and in vivo absorbance changes at 810 nm. TRV-VIGS caused a mild stress based on pigment content and light absorption characteristics in some cases. To assess transient complementation of NPQ, the endogenous psbS gene was silenced using only the transit sequence in the TRV vector followed by Agrobacterium-mediated transient expression of a modified gene consisting of an altered transit sequence fused to the native mature protein sequence. Nevertheless, NPQ in infused fully expanded leaves that expressed this re-introduced form was not fully restored indicating the possible importance of psbS incorporation prior to formation of grana stacks.
文摘Worldwide, wild birds play a vital role in the dispersal of ticks that harbour tick-borne pathogens, including Borrelia burgdorferi, the Lyme disease bacterium. Using PCR testing, we found 124 (31%) of 405 ticks (4 species), which were collected from 21 species of birds in far-western Canada, to be infected with B. burgdorferi. Transstadial transmission of B. burgdorferi occurred from larva to nymph, plus nymph to adult, in the avian coastal tick, Ixodes auritulus, collected from songbirds in British Columbia (B.C). Collectively, all 3 motile life stages (larva, nymph, adult) of this tick had an infection prevalence of 31% for B. burgdorferi, which suggests vector competency. A Pacific Wren was highly infested with I. auritulus immatures, and 20 (44%) of 45 ticks (2 nymphs, 43 larvae) were infected with B. burgdorferi. This heavy infestation shows the high potential to initiate a new population of ticks and to disseminate Lyme spirochetes. Epidemiologically, B. burgdorferi-infected I. auritulus larvae collected from the Spotted Towhee, Swainson’s Thrush, Pacific Wren, and Fox Sparrow suggest that these avian hosts act as reservoirs for B. burgdorferi. In this study, the western blacklegged tick, Ixodes pacificus, and Ixodes spinipalpis played a limited role in the enzootic transmission cycle of B. burgdorferi along coastal B.C. We document the first record of I. spinipalpis on a bird in Alberta. Because songbirds widely disperse Lyme disease vector ticks, primary health providers and the general public must be vigilant that outdoors people may be bitten by B. burgdorferi-infected ticks throughout far-western Canada.
基金Project supported by the US Department of Agriculture-Agriculture and Food Research Initiative(USDA-AFRI)(No.2011-67006-30181)the USDA-AFRI Hatch Program(No.MAS 00978)
基金Authors are appreciative to Dr.John Haines for allowing us access to type specimen of Stachybotrys elongata.The authors are also very grateful to Drs.Walter Gams,Rafael F.Castañeda Ruíz,Hongxin Mao,Weidong Wu,and Ariunaa Jalsrai for their assistance in finding literatures,especially the ones in Japan,Russia,and Ukraine.Without their assistance some references would not be available to us.This project was supported by the International Scientific Cooperated Project of Guizhou Province(No[2013]7004).
文摘Stachybotrys(asexual Hypocreales)has a worldwide distribution.This genus inhabits substrates rich in cellulose and is closely related to Memnoniella.Classification of species has previously been based on morphology,with conidial characters being considered as important.This study reevaluates Stachybotrys and Memnoniella,which is shown to include at least seven species-groups;while Memnoniella is a synonym of Stachybotrys.The sexual genera Ornatispora and Melanopsamma are also synonyms of Stachybotrys.With the exception of Stachybotrys subsimplex,species formed a wellsupported monophyletic group in LSU data analysis belonging to Stachybotriaceae.Seventy-four accepted Stachybotrys species are discussed,while eight species are considered to belong to other genera or are doubtful in this paper and a key to these species provided.Twelve new combinations and 1 nomina nova is proposed.The status of Stachybotrys species on health,as human or animal pathogens,in indoor environments,and use as biocontrol agents and compound discovery are also discussed.
