Stomata, the pores formed by a pair of guard cells, are the main gateways for water transpiration and photosynthetic CO2 exchange, as well as pathogen invasion in land plants. Guard cell movement is regulated by a com...Stomata, the pores formed by a pair of guard cells, are the main gateways for water transpiration and photosynthetic CO2 exchange, as well as pathogen invasion in land plants. Guard cell movement is regulated by a combination of environmental factors, including water status, light, CO2 levels and pathogen attack, as well as endogenous signals, such as abscisic acid and apoplastic reactive oxygen species （ROS）. Under abiotic and biotic stress conditions, extracellular ROS are mainly produced by plasma membrane-localized NADPH oxidases, whereas intracellular ROS are produced in multiple organelles. These ROS form a sophisticated cellular signaling network, with the accumulation of apoplastic ROS an early hallmark of stomatal movement. Here, we review recent progress in understanding the molecular mechanisms of the ROS signaling network, primarily during drought stress and pathogen attack. We summarize the roles of apoplastic ROS in regulating stomatal movement, ABA and CO2 signaling, and immunity responses. Finally, we discuss ROS accumulation and communication between organelles and cells. This information provides a conceptual framework for understanding how ROS signaling is integrated with various signaling pathways during plant responses to abiotic and biotic stress stimuli.展开更多
Herein based on literature available a hypothesis is provided about molecular basis for initial events in establishment interactions.This hypothesis asserts that:"recognition and interaction that occur between or...Herein based on literature available a hypothesis is provided about molecular basis for initial events in establishment interactions.This hypothesis asserts that:"recognition and interaction that occur between organisms is prearranged.There are membrane receptors with or without soluble components derived from the respective organisms that bridge specific interactions".Organisms'prearranged recognition theory(OPRT)can be specifically applied to host-microbe interactions where most microbes are coated(opsonised)by soluble components(opsonins)from the host,but there are also some microbes that can bypass host opsonization expressing receptors for the host cells or secreting host’s opsonin-like molecules.The receptors involved in organism's interactions,their specificity and repertoire depend on saccharides from glycoproteins,glycolipids,and polysaccharides(glycans)which are abundant extracellular components.Based in OPRT is possible to explain species-specific interactions and several other phenomena,such as hyper-infectivity,tissue tropism,differential sensitivity to disease depending on type O-blood,and tumoral cell promiscuity.The lipid raft domain in cellular membrane is proposed as the main location where interactions will trigger cellular responses.Possible scientific and biotechnology applications and alternative routes to modify organism's interactions and consequences are discussed.It is a novel hypothesis regarding the degree to which an organism's interactions are prearranged and the role of saccharides epitopes.展开更多
Molecular phylogenetic analyses of LSU rDNA demonstrate monophyly of the genus Melanconiella,and its status as a genus distinct from Melanconis is confirmed.Data of macro-and microscopic morphology,pure cultures and p...Molecular phylogenetic analyses of LSU rDNA demonstrate monophyly of the genus Melanconiella,and its status as a genus distinct from Melanconis is confirmed.Data of macro-and microscopic morphology,pure cultures and phylogenetic analyses of partial SSU-ITS-LSU rDNA,tef1 and rpb2 sequences revealed 13 distinct species of Melanconiella,six of which are described as new(M.chrysodiscosporina,M.chrysomelanconium,M.chrysorientalis,M.echinata,M.elegans,M.meridionalis).Melanconiella hyperopta var.orientalis is described as a new variety.Diaporthe carpinicola,D.ellisii,D.flavovirens,D.hyperopta and D.ostryae are formally combined into Melanconiella.The name Melanconiella chrysostroma is excluded from Melanconiella,as it is an obligate synonym of Wuestneia xanthostroma.The type of Melanconiella is confirmed as M.spodiaea.Several species are lecto-and/or epitypified.A key to all treated species ofMelanconiella is provided,and the circumscriptions of the genera Melanconis and Melanconiella are emended.Most Melanconiella species revealed by molecular phylogenetic analyses can be well characterised by a suite of morphological traits including ascospore shape,length and width,colour,absence/presence and shape of appendages and the anamorph.Anamorph-teleomorph connections were confirmed by pure culture and DNA data,revealing the presence of a single melanconium-or discosporina-like anamorph for each species.Colony growth was found to be characteristic of the respective species.Melanconiella is shown to be confined to the host family Betulaceae,and all species are found to be highly host-specific,mostly confined to a single host species.The biodiversity ofMelanconiella was determined to be centred on the genus Carpinus with nine species,five of which have been confirmed on C.betulus.Europe appears to be the geographic centre of Melanconiella biodiversity.展开更多
In plant pathology,the correct naming of a species is essential for determining the causal agents of disease.Species names not only serve the general purpose of concise communication,but also are critical for effectiv...In plant pathology,the correct naming of a species is essential for determining the causal agents of disease.Species names not only serve the general purpose of concise communication,but also are critical for effective plant quarantine,prevent-ing the introduction of new pathogens into a territory.Many phytopathogenic genera have multiple species and,in several genera,disagreements between the multiple prevailing species concept definitions result in numerous cryptic species.Some of these species were previously called by various names;forma speciales(specialised forms),subspecies,or pathotypes.However,based on new molecular evidence they are being assigned into new species.The frequent name changes and lack of consistent criteria to delineate cryptic species,species,subspecies,forms,and races create increasing confusion,often making communication among biologists arduous.Furthermore,such ambiguous information can convey misleading evo-lutionary concepts and species boundaries.The aim of this paper is to review these concepts,clarify their use,and evaluate them by referring to existing examples.We specifically address the question,“Do plant pathogens require a different ranking system?”We conclude that it is necessary to identify phytopathogens to species level based on data from multiple approaches.Furthermore,this identification must go beyond species level to clearly classify hitherto known subspecies,forms and races.In addition,when naming phytopathogenic genera,plant pathologists should provide more information about geographic locations and host ranges as well as host specificities for individual species,cryptic species,forms or races.When describing a new phytopathogen,we suggest that authors provide at least three representative strains together with pathogenicity test results.If Koch’s postulates cannot be fulfilled,it is necessary to provide complementary data such as associated disease severity on the host plant.Moreover,more sequenced collections of species causing diseases should be published i展开更多
Seeds from maize (Z. mays) plants whose stems received various treatment combinations of pathogen (F. verticillioides) and four antagonists (i.e. Trichoderma harzianum strain 2, T. hamatum, T. pseudokoningii strains 2...Seeds from maize (Z. mays) plants whose stems received various treatment combinations of pathogen (F. verticillioides) and four antagonists (i.e. Trichoderma harzianum strain 2, T. hamatum, T. pseudokoningii strains 2 and 5) in the field were subjected to fumonisin analysis. Three pairing methods were employed for the inoculation of pathogen and the antagonists into stem of the maize plant, viz., “Pathogen inoculated before Antagonist”, “Antagonist inoculated before Pathogen”, and “Antagonist and Pathogen inoculated simultaneously”. Controls include “Inoculation of pathogen alone”, “Inoculation of antagonist alone”, and “Inoculation of sterile toothpicks”. Inoculation method used was the toothpick method. Seeds were harvested five weeks after inoculation and subjected to fumonisin analysis. Resulting data were subjected to ANOVA using the GLM procedure of SAS. There was a high significance among treatments i.e. there were varying levels of fumonisin occurrence among the treatments and varying Fusarium occurrences within the blocks. Seeds from treatments involving “Inoculating T. pseudokoningii strain 5 alone” and “Inoculating T. harzianum strain 2 alone” had the highest mean fumonisin content (P > 0.01) which were not significantly higher than in control. Seeds from treatments involving “Inoculating T. pseudokoningii strain 5 and pathogen simultaneously” and “Inoculating T. harzianum strain 2 before pathogen” were significantly low in fumonisin content compared to seeds from other treatments. Seeds which received “Inoculation of T. hamatum alone” were also significantly low (P > 0.01) in fumonisin content compared to others. It could thus be said that treatments involving Trichoderma species applied in the maize stem might have an effect on the fumonisin content and hence Fusarium occurrence in the seeds depending on the occurrence pattern of the Trichoderma within the maize stem.展开更多
Fungal phytopathogens pose a serious threat to global crop production.Only a handful of strategies are available to combat these fungal infections,and the increasing incidence of fungicide resistance is making the sit...Fungal phytopathogens pose a serious threat to global crop production.Only a handful of strategies are available to combat these fungal infections,and the increasing incidence of fungicide resistance is making the situation worse.Hence,the molecular understanding of plant–fungus interactions remains a primary focus of plant pathology.One of the hallmarks of host–pathogen interactions is the overproduction of reactive oxygen species(ROS)as a plant defense mechanism,collectively termed the oxidative burst.In general,high accumulation of ROS restricts the growth of pathogenic organisms by causing localized cell death around the site of infection.To survive the oxidative burst and achieve successful host colonization,fungal phytopathogens employ intricate mechanisms for ROS perception,ROS neutralization,and protection from ROS-mediated damage.Together,these countermeasures maintain the physiological redox homeostasis that is essential for cell viability.In addition to intracellular antioxidant systems,phytopathogenic fungi also deploy interesting effector-mediated mechanisms for extracellular ROS modulation.This aspect of plant–pathogen interactions is significantly under-studied and provides enormous scope for future research.These adaptive responses,broadly categorized into“escape”and“exploitation”mechanisms,are poorly understood.In this review,we discuss the oxidative stress response of filamentous fungi,their perception signaling,and recent insights that provide a comprehensive understanding of the distinct survival mechanisms of fungal pathogens in response to the host-generated oxidative burst.展开更多
黔东南州的猕猴桃Actinidia chinensis产业对当地的经济发展起重要作用。为减少病害危害保证产品质量,对其野生猕猴桃和红心猕猴桃的病害发生情况进行调查研究,采用组织分离法对野生猕猴桃(wild species of Actinidia chinensis)和红心...黔东南州的猕猴桃Actinidia chinensis产业对当地的经济发展起重要作用。为减少病害危害保证产品质量,对其野生猕猴桃和红心猕猴桃的病害发生情况进行调查研究,采用组织分离法对野生猕猴桃(wild species of Actinidia chinensis)和红心猕猴桃(cultivated species of Actinidia chinensis)的病叶和病果进行病原真菌分离,使用核糖体rDNA-ITS(Internal transcribed spacer)区序列分析法进行DNA测序,使用MEGA4.0软件构建分子进化树,最后结合形态学观察对致病菌进行分类鉴定。结果表明:当前主要真菌病害有野生猕猴桃炭疽病(胶孢炭疽菌Colletotrichum gloeosporioides)、红心猕猴桃果实炭疽病(尖孢炭疽菌Colletotrichum acutatum)、红心猕猴桃叶片软腐病(变红镰刀菌Fusarium incarnatum)和红心猕猴桃褐斑病(互隔交链孢霉Alternaria alternata)。展开更多
基金supported by the National Key Scientific Research Project(2011CB915400)supported by the National Natural Science Foundation of China(31730007)
文摘Stomata, the pores formed by a pair of guard cells, are the main gateways for water transpiration and photosynthetic CO2 exchange, as well as pathogen invasion in land plants. Guard cell movement is regulated by a combination of environmental factors, including water status, light, CO2 levels and pathogen attack, as well as endogenous signals, such as abscisic acid and apoplastic reactive oxygen species （ROS）. Under abiotic and biotic stress conditions, extracellular ROS are mainly produced by plasma membrane-localized NADPH oxidases, whereas intracellular ROS are produced in multiple organelles. These ROS form a sophisticated cellular signaling network, with the accumulation of apoplastic ROS an early hallmark of stomatal movement. Here, we review recent progress in understanding the molecular mechanisms of the ROS signaling network, primarily during drought stress and pathogen attack. We summarize the roles of apoplastic ROS in regulating stomatal movement, ABA and CO2 signaling, and immunity responses. Finally, we discuss ROS accumulation and communication between organelles and cells. This information provides a conceptual framework for understanding how ROS signaling is integrated with various signaling pathways during plant responses to abiotic and biotic stress stimuli.
文摘Herein based on literature available a hypothesis is provided about molecular basis for initial events in establishment interactions.This hypothesis asserts that:"recognition and interaction that occur between organisms is prearranged.There are membrane receptors with or without soluble components derived from the respective organisms that bridge specific interactions".Organisms'prearranged recognition theory(OPRT)can be specifically applied to host-microbe interactions where most microbes are coated(opsonised)by soluble components(opsonins)from the host,but there are also some microbes that can bypass host opsonization expressing receptors for the host cells or secreting host’s opsonin-like molecules.The receptors involved in organism's interactions,their specificity and repertoire depend on saccharides from glycoproteins,glycolipids,and polysaccharides(glycans)which are abundant extracellular components.Based in OPRT is possible to explain species-specific interactions and several other phenomena,such as hyper-infectivity,tissue tropism,differential sensitivity to disease depending on type O-blood,and tumoral cell promiscuity.The lipid raft domain in cellular membrane is proposed as the main location where interactions will trigger cellular responses.Possible scientific and biotechnology applications and alternative routes to modify organism's interactions and consequences are discussed.It is a novel hypothesis regarding the degree to which an organism's interactions are prearranged and the role of saccharides epitopes.
基金We thank Walter Gams for hospitality and excursion support in Italy,Jacques Fournier,Enrique Rubio Domínguez,Sven-Åke Hanson and Larissa Vasilyeva for collecting and communicating Melanconiella specimens,Irmgard Greilhuber and her family for organising and participating in numerous collecting trips together with HV,the fungarium curators of B,BPI,DAOM,G,GZU,K,M,NY,UPS andWfor the loan of specimens,Scott Redhead(DAOM)for providing notes of L.E.Wehmeyer and for allowing DNA extraction from the type specimen of M.echinata,Walter Till(WU)for managing the herbarium loans,and the British Mycological Society for invitation to the BMS Spring Foray 2011 in Yorkshire.
文摘Molecular phylogenetic analyses of LSU rDNA demonstrate monophyly of the genus Melanconiella,and its status as a genus distinct from Melanconis is confirmed.Data of macro-and microscopic morphology,pure cultures and phylogenetic analyses of partial SSU-ITS-LSU rDNA,tef1 and rpb2 sequences revealed 13 distinct species of Melanconiella,six of which are described as new(M.chrysodiscosporina,M.chrysomelanconium,M.chrysorientalis,M.echinata,M.elegans,M.meridionalis).Melanconiella hyperopta var.orientalis is described as a new variety.Diaporthe carpinicola,D.ellisii,D.flavovirens,D.hyperopta and D.ostryae are formally combined into Melanconiella.The name Melanconiella chrysostroma is excluded from Melanconiella,as it is an obligate synonym of Wuestneia xanthostroma.The type of Melanconiella is confirmed as M.spodiaea.Several species are lecto-and/or epitypified.A key to all treated species ofMelanconiella is provided,and the circumscriptions of the genera Melanconis and Melanconiella are emended.Most Melanconiella species revealed by molecular phylogenetic analyses can be well characterised by a suite of morphological traits including ascospore shape,length and width,colour,absence/presence and shape of appendages and the anamorph.Anamorph-teleomorph connections were confirmed by pure culture and DNA data,revealing the presence of a single melanconium-or discosporina-like anamorph for each species.Colony growth was found to be characteristic of the respective species.Melanconiella is shown to be confined to the host family Betulaceae,and all species are found to be highly host-specific,mostly confined to a single host species.The biodiversity ofMelanconiella was determined to be centred on the genus Carpinus with nine species,five of which have been confirmed on C.betulus.Europe appears to be the geographic centre of Melanconiella biodiversity.
基金We would like to thank the Thailand Research Fund,Grant RDG6130001 entitled“Impact of climate change on fungal diversity and biogeography in the Greater Mekong Subregion”.Kevin D Hyde thanks Chiang Mai University for the award of a Visiting Professor.Ishara S Manawasinghe thank Prof Marco Thines for guiding the development of this paper by providing valuable ideas and comments.Alan JL Phillips acknowledges the support from UIDB/04046/2020 and UIDP/04046/2020 Centre grants from FCT,Portugal(to BioISI).
文摘In plant pathology,the correct naming of a species is essential for determining the causal agents of disease.Species names not only serve the general purpose of concise communication,but also are critical for effective plant quarantine,prevent-ing the introduction of new pathogens into a territory.Many phytopathogenic genera have multiple species and,in several genera,disagreements between the multiple prevailing species concept definitions result in numerous cryptic species.Some of these species were previously called by various names;forma speciales(specialised forms),subspecies,or pathotypes.However,based on new molecular evidence they are being assigned into new species.The frequent name changes and lack of consistent criteria to delineate cryptic species,species,subspecies,forms,and races create increasing confusion,often making communication among biologists arduous.Furthermore,such ambiguous information can convey misleading evo-lutionary concepts and species boundaries.The aim of this paper is to review these concepts,clarify their use,and evaluate them by referring to existing examples.We specifically address the question,“Do plant pathogens require a different ranking system?”We conclude that it is necessary to identify phytopathogens to species level based on data from multiple approaches.Furthermore,this identification must go beyond species level to clearly classify hitherto known subspecies,forms and races.In addition,when naming phytopathogenic genera,plant pathologists should provide more information about geographic locations and host ranges as well as host specificities for individual species,cryptic species,forms or races.When describing a new phytopathogen,we suggest that authors provide at least three representative strains together with pathogenicity test results.If Koch’s postulates cannot be fulfilled,it is necessary to provide complementary data such as associated disease severity on the host plant.Moreover,more sequenced collections of species causing diseases should be published i
文摘Seeds from maize (Z. mays) plants whose stems received various treatment combinations of pathogen (F. verticillioides) and four antagonists (i.e. Trichoderma harzianum strain 2, T. hamatum, T. pseudokoningii strains 2 and 5) in the field were subjected to fumonisin analysis. Three pairing methods were employed for the inoculation of pathogen and the antagonists into stem of the maize plant, viz., “Pathogen inoculated before Antagonist”, “Antagonist inoculated before Pathogen”, and “Antagonist and Pathogen inoculated simultaneously”. Controls include “Inoculation of pathogen alone”, “Inoculation of antagonist alone”, and “Inoculation of sterile toothpicks”. Inoculation method used was the toothpick method. Seeds were harvested five weeks after inoculation and subjected to fumonisin analysis. Resulting data were subjected to ANOVA using the GLM procedure of SAS. There was a high significance among treatments i.e. there were varying levels of fumonisin occurrence among the treatments and varying Fusarium occurrences within the blocks. Seeds from treatments involving “Inoculating T. pseudokoningii strain 5 alone” and “Inoculating T. harzianum strain 2 alone” had the highest mean fumonisin content (P > 0.01) which were not significantly higher than in control. Seeds from treatments involving “Inoculating T. pseudokoningii strain 5 and pathogen simultaneously” and “Inoculating T. harzianum strain 2 before pathogen” were significantly low in fumonisin content compared to seeds from other treatments. Seeds which received “Inoculation of T. hamatum alone” were also significantly low (P > 0.01) in fumonisin content compared to others. It could thus be said that treatments involving Trichoderma species applied in the maize stem might have an effect on the fumonisin content and hence Fusarium occurrence in the seeds depending on the occurrence pattern of the Trichoderma within the maize stem.
基金supported by a core grant from the National Institute of Plant Genome Research,New Delhi and Department of Biotechnology(DBT),Goverment of Indiathe DBT and the Department of Science and Technology(DST),Government of India,for DBT-SRF and DST-INSPIRE research fellowships,respectively.
文摘Fungal phytopathogens pose a serious threat to global crop production.Only a handful of strategies are available to combat these fungal infections,and the increasing incidence of fungicide resistance is making the situation worse.Hence,the molecular understanding of plant–fungus interactions remains a primary focus of plant pathology.One of the hallmarks of host–pathogen interactions is the overproduction of reactive oxygen species(ROS)as a plant defense mechanism,collectively termed the oxidative burst.In general,high accumulation of ROS restricts the growth of pathogenic organisms by causing localized cell death around the site of infection.To survive the oxidative burst and achieve successful host colonization,fungal phytopathogens employ intricate mechanisms for ROS perception,ROS neutralization,and protection from ROS-mediated damage.Together,these countermeasures maintain the physiological redox homeostasis that is essential for cell viability.In addition to intracellular antioxidant systems,phytopathogenic fungi also deploy interesting effector-mediated mechanisms for extracellular ROS modulation.This aspect of plant–pathogen interactions is significantly under-studied and provides enormous scope for future research.These adaptive responses,broadly categorized into“escape”and“exploitation”mechanisms,are poorly understood.In this review,we discuss the oxidative stress response of filamentous fungi,their perception signaling,and recent insights that provide a comprehensive understanding of the distinct survival mechanisms of fungal pathogens in response to the host-generated oxidative burst.
文摘黔东南州的猕猴桃Actinidia chinensis产业对当地的经济发展起重要作用。为减少病害危害保证产品质量,对其野生猕猴桃和红心猕猴桃的病害发生情况进行调查研究,采用组织分离法对野生猕猴桃(wild species of Actinidia chinensis)和红心猕猴桃(cultivated species of Actinidia chinensis)的病叶和病果进行病原真菌分离,使用核糖体rDNA-ITS(Internal transcribed spacer)区序列分析法进行DNA测序,使用MEGA4.0软件构建分子进化树,最后结合形态学观察对致病菌进行分类鉴定。结果表明:当前主要真菌病害有野生猕猴桃炭疽病(胶孢炭疽菌Colletotrichum gloeosporioides)、红心猕猴桃果实炭疽病(尖孢炭疽菌Colletotrichum acutatum)、红心猕猴桃叶片软腐病(变红镰刀菌Fusarium incarnatum)和红心猕猴桃褐斑病(互隔交链孢霉Alternaria alternata)。
