Aerobiology is the study of airborne biological particles and their movement and impact. Plant pathogen spores can be dispersed actively through mechanisms like bursting structures or passively through wind and rain splash. Spores are transported by wind horizontally over long distances and vertically upward before settling through sedimentation, impaction, or rain deposition. The scale of disease spread can be microscale within a field, mesoscale over many fields in a season, or synoptic scale over continents over years. Concentration gradients decrease spore levels downwind from the source.
Vernalization is the process by which flowering is promoted through a cold treatment given to hydrated seeds or growing plants. Cold exposure cuts short the vegetative period, resulting in early flowering. Two main theories explain vernalization's mechanism: the phasic development theory proposes cold exposure accelerates plant development phases, while hormonal theories suggest cold induces a floral hormone called vernalin. Epigenetic changes in gene expression from cold exposure may also play a role, stably altering flowering gene expression even after the cold is removed. Vernalization has practical applications in agriculture by promoting early flowering, increasing disease resistance, and aiding crop improvement.
This document discusses soil horizons and their components. It describes the key horizons of soil - the O horizon containing organic matter on top, followed by the A horizon containing dark humus, then the B horizon where humus becomes less abundant, and finally the C horizon consisting of unmodified parent material. The A horizon can be further divided into thinner layers containing leaf litter, fermenting litter, humus, and eluviated soil. Soil horizons are important because they show how soil forms and minerals are redistributed over time.
Microbes play an essential role in soil properties and plant growth. They are responsible for decomposing organic matter, fixing nitrogen, and managing soil stability through various biochemical processes. The four main types of microbes found in soil are bacteria, fungi, actinomycetes, and algae. Each group serves important functions like nutrient cycling, organic matter breakdown, and maintaining balances in the soil environment. Microbes also influence soil structure by producing compounds that bind soil particles together and form stable aggregates.
The document discusses various methods for controlling plant diseases, including regulatory, cultural, biological, physical, and chemical methods. Regulatory methods aim to prevent the spread of pathogens through quarantines and inspections. Cultural methods manipulate the environment and genetics of plants, such as host eradication, crop rotation, and improving growing conditions. Biological methods use other organisms like resistant plant varieties and hyperparasites. Physical methods employ heat, refrigeration, and radiation. Chemical methods apply fungicides, bactericides, and insecticides through foliage sprays and dusts.
The document summarizes the process of isolating and purifying plant viruses. It involves homogenizing infected plant leaves and extracting the sap containing viruses. The sap is then fractionated through low and high-speed centrifugation to separate out virus particles from other materials. The virus particles are further purified using density gradient centrifugation, which separates viruses based on their density through ultracentrifugation in layers of sucrose solutions with different densities. The purified virus band is collected and dialyzed to remove sucrose, yielding isolated and purified plant viruses. Key techniques used include density gradient centrifugation and ultracentrifugation.
The document summarizes the life cycle of mushrooms. Mushrooms grow in moist, dark places on decaying organic matter. Their life cycle begins as a spore and progresses through five stages, ending when the fruiting body releases new spores. Key stages include the mycelium, basidium, basidiospore, and basidiocarp. Mushrooms are an important source of protein, vitamins, and minerals. Mushroom farming is common in Nepal and produces around 8-10 tons per day, with oyster and white button mushrooms among the edible varieties grown.
Vernalization is the process by which flowering is promoted through a cold treatment given to hydrated seeds or growing plants. Cold exposure cuts short the vegetative period, resulting in early flowering. Two main theories explain vernalization's mechanism: the phasic development theory proposes cold exposure accelerates plant development phases, while hormonal theories suggest cold induces a floral hormone called vernalin. Epigenetic changes in gene expression from cold exposure may also play a role, stably altering flowering gene expression even after the cold is removed. Vernalization has practical applications in agriculture by promoting early flowering, increasing disease resistance, and aiding crop improvement.
This document discusses soil horizons and their components. It describes the key horizons of soil - the O horizon containing organic matter on top, followed by the A horizon containing dark humus, then the B horizon where humus becomes less abundant, and finally the C horizon consisting of unmodified parent material. The A horizon can be further divided into thinner layers containing leaf litter, fermenting litter, humus, and eluviated soil. Soil horizons are important because they show how soil forms and minerals are redistributed over time.
Microbes play an essential role in soil properties and plant growth. They are responsible for decomposing organic matter, fixing nitrogen, and managing soil stability through various biochemical processes. The four main types of microbes found in soil are bacteria, fungi, actinomycetes, and algae. Each group serves important functions like nutrient cycling, organic matter breakdown, and maintaining balances in the soil environment. Microbes also influence soil structure by producing compounds that bind soil particles together and form stable aggregates.
The document discusses various methods for controlling plant diseases, including regulatory, cultural, biological, physical, and chemical methods. Regulatory methods aim to prevent the spread of pathogens through quarantines and inspections. Cultural methods manipulate the environment and genetics of plants, such as host eradication, crop rotation, and improving growing conditions. Biological methods use other organisms like resistant plant varieties and hyperparasites. Physical methods employ heat, refrigeration, and radiation. Chemical methods apply fungicides, bactericides, and insecticides through foliage sprays and dusts.
The document summarizes the process of isolating and purifying plant viruses. It involves homogenizing infected plant leaves and extracting the sap containing viruses. The sap is then fractionated through low and high-speed centrifugation to separate out virus particles from other materials. The virus particles are further purified using density gradient centrifugation, which separates viruses based on their density through ultracentrifugation in layers of sucrose solutions with different densities. The purified virus band is collected and dialyzed to remove sucrose, yielding isolated and purified plant viruses. Key techniques used include density gradient centrifugation and ultracentrifugation.
The document summarizes the life cycle of mushrooms. Mushrooms grow in moist, dark places on decaying organic matter. Their life cycle begins as a spore and progresses through five stages, ending when the fruiting body releases new spores. Key stages include the mycelium, basidium, basidiospore, and basidiocarp. Mushrooms are an important source of protein, vitamins, and minerals. Mushroom farming is common in Nepal and produces around 8-10 tons per day, with oyster and white button mushrooms among the edible varieties grown.
This document discusses principles of disease control in agricultural microbiology. It outlines four main principles: 1) Avoidance/Exclusion to prevent import and spread of pathogens, 2) Eradiation to reduce pathogen amounts, 3) Protection to directly protect plants from infection, and 4) Resistant varieties that hinder pathogen development. Specific control methods are described under each principle, including quarantine, sanitation, crop rotation, biological and chemical controls, and genetic engineering to develop resistant varieties.
The document discusses the symbiotic relationship between plant roots and fungi known as mycorrhizae. Mycorrhizal fungi form structures around and between plant roots called Hartig nets. This increases the plant's absorption of water and nutrients from soil. In exchange, the plant provides the fungus with sugars and amino acids from photosynthesis. There are two types of mycorrhizal associations - ectomycorrhizal where the fungus forms a sheath around the root, and endomycorrhizal where the fungus grows into the root cortex.
mycorrhiza types, distribution and significance.shabnoorshaikh1
This document discusses the types, distribution, and significance of mycorrhiza. It describes the two main types - endomycorrhiza and ectomycorrhiza - and their subtypes, including vesicular arbuscular mycorrhiza (VAM), ericoid mycorrhiza, and orchid mycorrhiza. It notes that over 90% of land plants form mycorrhizal associations, which involve a three-way interaction between the host plant, fungi, and soil factors. The document also outlines the global distribution of different mycorrhizal types and discusses the agricultural significance of mycorrhizae in improving plant nutrient uptake, tolerance to stress, and soil structure.
DEFENCE MECHANISM IN PLANTS AGAINST PATHOGENS (STRUCTURAL & BIOCHEMICAL) ansarishahid786
Plants have both structural and biochemical defense mechanisms against pathogens. Structural defenses include pre-existing traits like thick cuticles and presence of thick-walled cells, as well as induced responses like formation of cork layers and tyloses after infection. Biochemical defenses include pre-existing inhibitory compounds and enzymes, as well as induced responses like phytoalexins, hypersensitive response, and transgenic production of plantibodies after pathogen detection. Together these defenses provide multiple layers of protection against the wide variety of fungi, bacteria, viruses and other pathogens that plants encounter.
This document summarizes information about programmed cell death (PCD) in plants. It discusses how PCD is essential for plant development and defense. There are two main classes of plant PCD - developmental and defensive. Developmental PCD regulates cell division and organ development, while defensive PCD helps destroy infected cells and activate systemic resistance. PCD is controlled by genetically regulated proteases like metacaspases and vacuolar processing enzymes. Hypersensitive response is a form of defensive PCD that rapidly kills cells at infection sites. Necrosis differs from PCD in that it is an unregulated form of cell death caused by injury rather than an active suicide process.
DEFINITION OF PHYLLOSPHERE
PARTS OF PHYLLOSPHERE
MICROORGANISM OF PHYLLOSPHERE
PHYLLOSPHERE MICROORGANISMS OF STEM (CAULOSPHERE)
PHYLLOSPHERE MICROORGANISMS OF LEAVES(PHYLLOPLANE)
PHYLLOSPHERE MICROORGANISMS OF FLOWER (ANTHOSPHERE)
PHYLLOSPHERE MICROORGANISMS OF FRUIT(CARPOSPHERE)
FACTORS INFLUENCING MICROBIAL GROWTH AND ACTIVITIES
POSITIVE EFFECT OF PHYLLOSPHERE MICROORGANISMS
NEGATIVE EFFECT OF PHYLLOSPHERE MICROORGANISMS
The term 'Biofertilizer' itself means 'Live
Fertilizer'.
contain live or latent beneficial microbes
which help to fix atmospheric nitrogen,
solubilize
and
mobilize
phosphorus,
translocate minor elements (Zinc, Copper,
etc.,) to the plants, produce plant growth
promoting hormones, vitamins, amino acids
and control plant pathogenic fungi
This document discusses various methods for controlling plant diseases. The major methods discussed are cultural control methods, biological control methods, and chemical control methods. Cultural control methods include avoiding contact between the pathogen and host plant through proper field selection, resistant varieties, and modifying cultural practices. Biological control uses other organisms like fungi, bacteria, and mycorrhizal fungi to control pathogens. Chemical control involves the use of fungicides, bactericides, and other chemical treatments to directly kill or inhibit pathogens.
This document discusses biological control of plant diseases. Biological control involves using living organisms to control pests. It has received more attention recently. Some advantages are that it is specific to pests and cheaper after initial costs. Disadvantages include narrow effectiveness and high start-up expenses. Biological control agents include parasitoids, pathogens, and predators. Parasitoids lay eggs on or in a host insect and kill it. Pathogens infect insects and kill them or affect future generations. Predators are larger than prey and eat several. The document also discusses antagonists that compete with or produce toxins against plant pathogens. Common release methods are inoculative, where small numbers are released to spread, and augmentation, where organisms are mass
This document summarizes how plant virus infections affect host plant metabolism. It discusses how photosynthesis, respiration, permeability, and other metabolic processes are impacted. Plant viruses are transmitted either horizontally through external means like pruning or vertically through seeds. The virus infection decreases photosynthesis and increases respiration and ethylene production. It also makes cell membranes more permeable and affects protein synthesis, carbohydrate transport, and nucleic acid and amino acid levels. Overall, the virus hijacks the plant's normal metabolic processes to facilitate its replication and spread.
Cyanide-insensitive respiration is a respiratory pathway found in the mitochondria of some plants, yeasts, and bacteria that is unaffected by cyanide. It involves an alternative oxidase (AOX) that allows electrons to bypass the cytochrome c oxidase in the electron transport chain. AOX is a homodimeric integral membrane protein that transfers electrons from ubiquinone directly to oxygen without proton pumping. This pathway releases energy as heat rather than generating a proton gradient for ATP synthesis. Cyanide-insensitive respiration is not found in animal cells.
Effect of pathogen on plant physiologyGowthamfarms
This document discusses the effects of virus, bacterial, and fungal infections on plant physiology. It summarizes that virus infections can reduce chloroplast numbers and chlorophyll content, as well as stimulation of early CO2 incorporation but decline after several days of infection. Bacterial infections can decrease chloroplast stroma and destroy chloroplast integrity, suppressing CO2 fixation. Fungal infections can reduce chloroplast content and inhibit processes like photophosphorylation and electron transport, suppressing CO2 fixation. It also discusses the process of plant respiration and how respiration rates increase in diseased plants as they use reserve carbohydrates faster than healthy tissues.
This document discusses Tobacco Mosaic Virus (TMV), which infects over 350 plant species including economically important crops like tobacco and tomatoes. TMV is a rod-shaped virus composed of RNA and coat proteins. It replicates by translating its RNA inside plant cells and using movement proteins to spread between cells. Infection causes mosaic patterns, necrosis, curling and stunted growth. TMV is transmitted mechanically through contaminated tools or plant material and can overwinter in weeds or debris. Management strategies include using virus-free plants, removing weeds, disinfecting tools, and propagating through seed rather than vegetative material.
Plant hormones are naturally occurring organic substances that affect physiological processes. There are five major groups of plant hormones, such as auxins, gibberellins, cytokinins, abscisic acid and ethylene. In this presentation deals with Cytokinins with its biosynthesis, transport, pathways and physiological effects.
1. The document discusses the defense mechanisms of plants against plant pathogens, including structural and biochemical defenses.
2. Structural defenses include pre-existing structures like wax, thick cuticles, and thick-walled cells, as well as induced structures like cork layers and tyloses formation in response to infection.
3. Biochemical defenses include pre-existing inhibitors and phenolic compounds, as well as induced responses like phytoalexin production, hypersensitive response, and pathogenesis-related protein synthesis post-infection.
4. Both structural and biochemical defenses work together and are influenced by factors like the plant's age, organ infected, and environmental conditions.
The document discusses the rhizosphere and phyllosphere, which are the regions of soil and plant surfaces influenced by microorganisms. The rhizosphere refers to the region of soil directly influenced by root secretions and microbes. It includes the inner and outer rhizosphere zones. Microbes in the rhizosphere play important roles in plant nutrition, growth promotion, and disease suppression. The phyllosphere refers to the interface between leaves and air, and is inhabited by bacteria, yeast and fungi that can benefit plants through nutrient management, disease control and stress tolerance.
The document discusses host-pathogen interactions and plant parasitism. It begins by defining key terms like host-pathogen interaction and parasitism. It then describes how pathogens can infect hosts on a molecular and cellular level. It discusses the disease cycle, including inoculation, penetration, infection, and dissemination. It explains different types of pathogen interactions with hosts, including obligate and nonobligate parasites. It also discusses symbiotic relationships between some microbes and plants. In summary, the document provides an overview of host-pathogen interactions, the disease cycle, and different types of parasitic relationships between microbes and plants.
photoperiodism its discovery,significance,classifications,mechanism,critical day length,quality of light, night break phenomenon,phytochrome.florigen,floering genes, circadian rhythm
Ultrastructure of fungal cell and different type ofjeeva raj
This document is a seminar report submitted by Jeeva Raj Joseph on the ultrastructure of fungal cells and different types of spores. It discusses the key components of the fungal cell, including the cell wall, plasma membrane, cytoplasm, organelles, and inclusions. It describes the different types of septa that can divide fungal hyphae. The report also examines the two main types of asexual spores - sporangiospores and conidia - and provides details on different subtypes like arthrospores, blastospores, and phialospores. Finally, it briefly discusses sexually produced spores and how certain spore types are characteristic of different fungal taxa.
This document discusses the sources and forms of discharge of airborne microbes. It outlines that microbes can become airborne from soil, water, wind and tides, and human activities like coughing or sneezing. Microbes are expelled in three forms: droplets from sneezing or coughing that are large and fall quickly from the air; droplet nuclei that remain after droplets evaporate and are very small, remaining airborne for hours; and infectious dust particles that form when droplets dry on surfaces and become re-aerosolized. The size and moisture content of expelled particles determines how long microbes remain suspended in the air.
Aerobiology is the study of biological materials that are aerosolized and transmitted through the air. It involves the study of life in the air, the dispersal of substances like viruses in aerosol form, and diseases transmitted via respiratory routes. Key aspects include the composition and size of bioaerosols, effects of particulate matter inhalation, atmospheric layers involved in transporting particles, and the launching and deposition processes by which microbes become airborne and land in new environments. An example is the Spanish flu pandemic of 1918-1920, which spread rapidly worldwide and caused 50-100 million deaths.
This document discusses principles of disease control in agricultural microbiology. It outlines four main principles: 1) Avoidance/Exclusion to prevent import and spread of pathogens, 2) Eradiation to reduce pathogen amounts, 3) Protection to directly protect plants from infection, and 4) Resistant varieties that hinder pathogen development. Specific control methods are described under each principle, including quarantine, sanitation, crop rotation, biological and chemical controls, and genetic engineering to develop resistant varieties.
The document discusses the symbiotic relationship between plant roots and fungi known as mycorrhizae. Mycorrhizal fungi form structures around and between plant roots called Hartig nets. This increases the plant's absorption of water and nutrients from soil. In exchange, the plant provides the fungus with sugars and amino acids from photosynthesis. There are two types of mycorrhizal associations - ectomycorrhizal where the fungus forms a sheath around the root, and endomycorrhizal where the fungus grows into the root cortex.
mycorrhiza types, distribution and significance.shabnoorshaikh1
This document discusses the types, distribution, and significance of mycorrhiza. It describes the two main types - endomycorrhiza and ectomycorrhiza - and their subtypes, including vesicular arbuscular mycorrhiza (VAM), ericoid mycorrhiza, and orchid mycorrhiza. It notes that over 90% of land plants form mycorrhizal associations, which involve a three-way interaction between the host plant, fungi, and soil factors. The document also outlines the global distribution of different mycorrhizal types and discusses the agricultural significance of mycorrhizae in improving plant nutrient uptake, tolerance to stress, and soil structure.
DEFENCE MECHANISM IN PLANTS AGAINST PATHOGENS (STRUCTURAL & BIOCHEMICAL) ansarishahid786
Plants have both structural and biochemical defense mechanisms against pathogens. Structural defenses include pre-existing traits like thick cuticles and presence of thick-walled cells, as well as induced responses like formation of cork layers and tyloses after infection. Biochemical defenses include pre-existing inhibitory compounds and enzymes, as well as induced responses like phytoalexins, hypersensitive response, and transgenic production of plantibodies after pathogen detection. Together these defenses provide multiple layers of protection against the wide variety of fungi, bacteria, viruses and other pathogens that plants encounter.
This document summarizes information about programmed cell death (PCD) in plants. It discusses how PCD is essential for plant development and defense. There are two main classes of plant PCD - developmental and defensive. Developmental PCD regulates cell division and organ development, while defensive PCD helps destroy infected cells and activate systemic resistance. PCD is controlled by genetically regulated proteases like metacaspases and vacuolar processing enzymes. Hypersensitive response is a form of defensive PCD that rapidly kills cells at infection sites. Necrosis differs from PCD in that it is an unregulated form of cell death caused by injury rather than an active suicide process.
DEFINITION OF PHYLLOSPHERE
PARTS OF PHYLLOSPHERE
MICROORGANISM OF PHYLLOSPHERE
PHYLLOSPHERE MICROORGANISMS OF STEM (CAULOSPHERE)
PHYLLOSPHERE MICROORGANISMS OF LEAVES(PHYLLOPLANE)
PHYLLOSPHERE MICROORGANISMS OF FLOWER (ANTHOSPHERE)
PHYLLOSPHERE MICROORGANISMS OF FRUIT(CARPOSPHERE)
FACTORS INFLUENCING MICROBIAL GROWTH AND ACTIVITIES
POSITIVE EFFECT OF PHYLLOSPHERE MICROORGANISMS
NEGATIVE EFFECT OF PHYLLOSPHERE MICROORGANISMS
The term 'Biofertilizer' itself means 'Live
Fertilizer'.
contain live or latent beneficial microbes
which help to fix atmospheric nitrogen,
solubilize
and
mobilize
phosphorus,
translocate minor elements (Zinc, Copper,
etc.,) to the plants, produce plant growth
promoting hormones, vitamins, amino acids
and control plant pathogenic fungi
This document discusses various methods for controlling plant diseases. The major methods discussed are cultural control methods, biological control methods, and chemical control methods. Cultural control methods include avoiding contact between the pathogen and host plant through proper field selection, resistant varieties, and modifying cultural practices. Biological control uses other organisms like fungi, bacteria, and mycorrhizal fungi to control pathogens. Chemical control involves the use of fungicides, bactericides, and other chemical treatments to directly kill or inhibit pathogens.
This document discusses biological control of plant diseases. Biological control involves using living organisms to control pests. It has received more attention recently. Some advantages are that it is specific to pests and cheaper after initial costs. Disadvantages include narrow effectiveness and high start-up expenses. Biological control agents include parasitoids, pathogens, and predators. Parasitoids lay eggs on or in a host insect and kill it. Pathogens infect insects and kill them or affect future generations. Predators are larger than prey and eat several. The document also discusses antagonists that compete with or produce toxins against plant pathogens. Common release methods are inoculative, where small numbers are released to spread, and augmentation, where organisms are mass
This document summarizes how plant virus infections affect host plant metabolism. It discusses how photosynthesis, respiration, permeability, and other metabolic processes are impacted. Plant viruses are transmitted either horizontally through external means like pruning or vertically through seeds. The virus infection decreases photosynthesis and increases respiration and ethylene production. It also makes cell membranes more permeable and affects protein synthesis, carbohydrate transport, and nucleic acid and amino acid levels. Overall, the virus hijacks the plant's normal metabolic processes to facilitate its replication and spread.
Cyanide-insensitive respiration is a respiratory pathway found in the mitochondria of some plants, yeasts, and bacteria that is unaffected by cyanide. It involves an alternative oxidase (AOX) that allows electrons to bypass the cytochrome c oxidase in the electron transport chain. AOX is a homodimeric integral membrane protein that transfers electrons from ubiquinone directly to oxygen without proton pumping. This pathway releases energy as heat rather than generating a proton gradient for ATP synthesis. Cyanide-insensitive respiration is not found in animal cells.
Effect of pathogen on plant physiologyGowthamfarms
This document discusses the effects of virus, bacterial, and fungal infections on plant physiology. It summarizes that virus infections can reduce chloroplast numbers and chlorophyll content, as well as stimulation of early CO2 incorporation but decline after several days of infection. Bacterial infections can decrease chloroplast stroma and destroy chloroplast integrity, suppressing CO2 fixation. Fungal infections can reduce chloroplast content and inhibit processes like photophosphorylation and electron transport, suppressing CO2 fixation. It also discusses the process of plant respiration and how respiration rates increase in diseased plants as they use reserve carbohydrates faster than healthy tissues.
This document discusses Tobacco Mosaic Virus (TMV), which infects over 350 plant species including economically important crops like tobacco and tomatoes. TMV is a rod-shaped virus composed of RNA and coat proteins. It replicates by translating its RNA inside plant cells and using movement proteins to spread between cells. Infection causes mosaic patterns, necrosis, curling and stunted growth. TMV is transmitted mechanically through contaminated tools or plant material and can overwinter in weeds or debris. Management strategies include using virus-free plants, removing weeds, disinfecting tools, and propagating through seed rather than vegetative material.
Plant hormones are naturally occurring organic substances that affect physiological processes. There are five major groups of plant hormones, such as auxins, gibberellins, cytokinins, abscisic acid and ethylene. In this presentation deals with Cytokinins with its biosynthesis, transport, pathways and physiological effects.
1. The document discusses the defense mechanisms of plants against plant pathogens, including structural and biochemical defenses.
2. Structural defenses include pre-existing structures like wax, thick cuticles, and thick-walled cells, as well as induced structures like cork layers and tyloses formation in response to infection.
3. Biochemical defenses include pre-existing inhibitors and phenolic compounds, as well as induced responses like phytoalexin production, hypersensitive response, and pathogenesis-related protein synthesis post-infection.
4. Both structural and biochemical defenses work together and are influenced by factors like the plant's age, organ infected, and environmental conditions.
The document discusses the rhizosphere and phyllosphere, which are the regions of soil and plant surfaces influenced by microorganisms. The rhizosphere refers to the region of soil directly influenced by root secretions and microbes. It includes the inner and outer rhizosphere zones. Microbes in the rhizosphere play important roles in plant nutrition, growth promotion, and disease suppression. The phyllosphere refers to the interface between leaves and air, and is inhabited by bacteria, yeast and fungi that can benefit plants through nutrient management, disease control and stress tolerance.
The document discusses host-pathogen interactions and plant parasitism. It begins by defining key terms like host-pathogen interaction and parasitism. It then describes how pathogens can infect hosts on a molecular and cellular level. It discusses the disease cycle, including inoculation, penetration, infection, and dissemination. It explains different types of pathogen interactions with hosts, including obligate and nonobligate parasites. It also discusses symbiotic relationships between some microbes and plants. In summary, the document provides an overview of host-pathogen interactions, the disease cycle, and different types of parasitic relationships between microbes and plants.
photoperiodism its discovery,significance,classifications,mechanism,critical day length,quality of light, night break phenomenon,phytochrome.florigen,floering genes, circadian rhythm
Ultrastructure of fungal cell and different type ofjeeva raj
This document is a seminar report submitted by Jeeva Raj Joseph on the ultrastructure of fungal cells and different types of spores. It discusses the key components of the fungal cell, including the cell wall, plasma membrane, cytoplasm, organelles, and inclusions. It describes the different types of septa that can divide fungal hyphae. The report also examines the two main types of asexual spores - sporangiospores and conidia - and provides details on different subtypes like arthrospores, blastospores, and phialospores. Finally, it briefly discusses sexually produced spores and how certain spore types are characteristic of different fungal taxa.
This document discusses the sources and forms of discharge of airborne microbes. It outlines that microbes can become airborne from soil, water, wind and tides, and human activities like coughing or sneezing. Microbes are expelled in three forms: droplets from sneezing or coughing that are large and fall quickly from the air; droplet nuclei that remain after droplets evaporate and are very small, remaining airborne for hours; and infectious dust particles that form when droplets dry on surfaces and become re-aerosolized. The size and moisture content of expelled particles determines how long microbes remain suspended in the air.
Aerobiology is the study of biological materials that are aerosolized and transmitted through the air. It involves the study of life in the air, the dispersal of substances like viruses in aerosol form, and diseases transmitted via respiratory routes. Key aspects include the composition and size of bioaerosols, effects of particulate matter inhalation, atmospheric layers involved in transporting particles, and the launching and deposition processes by which microbes become airborne and land in new environments. An example is the Spanish flu pandemic of 1918-1920, which spread rapidly worldwide and caused 50-100 million deaths.
A SEMINAR REPORT ON AIR MICROFLORA.
In addition to gases, dust particles and water vapour, air also contains microorganisms. There are vegetative cells and spores of bacteria, fungi and algae, viruses and protozoan cysts (Rintala et al., 2018).
Since air is often exposed to sunlight, it has a higher temperature and less moisture. So, if not protected from desiccation, most of these microbial forms will die. Air is mainly it transport or dispersal medium for microorganisms (Rintala et al., 2018).
They occur in relatively small numbers in air when compared with soil or water. The microflora of air can be studied under two headings outdoor and indoor microflora (Rintala et al., 2018).
The use of high efficient particulate air filters and immunization should be employed to control the spread of these airborne diseases. Obviously, the presence of a good ventilation system inside buildings eliminates to some extent the influence of indoor and outdoor sources. Proper ventilation helps to dilute the negative effects of indoor and outdoor air.
The document provides an introduction to aeromicrobiology, which is the study of microorganisms present in air. It discusses the composition of air and how it lacks nutrients and water, making it an unfavorable environment for microbial growth. However, microbes can become suspended in air within water droplets or dust particles. The document outlines the different physical habitats of microbes in the air, including the layers of the atmosphere and clouds. It also describes the types of microorganisms that can be found as bioaerosols and discusses their potential to cause disease. Sources of airborne microbes and factors influencing their survival are summarized.
This document provides an overview of a course on plant pathology and diseases of field crops. The course is taught by K. M. Golam Dastogeer in the Department of Plant Pathology at Bangladesh Agricultural University. The document discusses various topics that will be covered in the course, including the definition and necessity of pathogen dissemination, types of dispersal, and modes of pathogen dissemination such as wind, water, humans, birds, insects, and animals. It provides examples of different pathogens dispersed by these various modes and factors affecting wind dissemination. The role of insects, humans, birds, farm animals, and other agents in pathogen dispersal is also summarized. Finally, recommended textbooks on plant pathology are listed.
This document discusses microbiology in the air or atmosphere. It defines air microbiology as the scientific study of microorganisms like bacteria, archaea, fungi and viruses found in the atmospheric air. Microorganisms are normally present within 300 to 10,000 feet above land. Specific microbes found at different altitudes are mentioned. Places like hospitals and schools housing infected individuals contain pathogens like tuberculosis bacteria or influenza viruses. Factors like temperature, light, moisture and nutrients make the atmosphere inhospitable for microbial growth. The document further discusses the definition and composition of air, sources of airborne microorganisms, their significance and methods to study and control microbes in air.
The document discusses the microbiology of air and bioaerosols. It defines bioaerosols as microorganisms and their byproducts suspended in the atmosphere. It describes the history of the field beginning with Darwin's observations of dust particles and Pasteur's early research isolating airborne microbes. It also outlines the types of microbes found indoors and outdoors, how they are transmitted through the air, and factors like temperature, humidity and altitude that influence their presence. Finally, it discusses bioaerosols as human health hazards and different sampling methods used to study airborne microbes.
This document discusses plant virus epidemiology. It defines epidemiology as the study of disease development in plant populations over time and space, influenced by environmental and human factors. The key components of virus epidemiology are the virus, host, vector, and environment. Disease development is studied through disease progress curves and disease gradient curves. Monitoring methods include visual inspection, indexing of infected plants, and use of bait plants. Environmental factors like temperature, rainfall, and wind influence the virus, vector, and host.
The document discusses sources of microorganisms in air. It states that the main sources are soil, water, plant and animal surfaces, and human beings. Microbes from these sources enter the air through environmental factors like wind and water, or human activities like digging and talking. Once airborne, microbes can exist as droplets, droplet nuclei, or infectious dust, with droplet nuclei able to remain suspended the longest. The largest source is human beings through sneezing, coughing, and other activities that expel microbes from our respiratory tracts in bioaerosols.
Pythium aphanidermatum and Pythium debaryanum are soil-borne fungal pathogens that cause damping off disease in tobacco seedlings, leading to pre-emergence and post-emergence damping off that kills seedlings. The pathogens favor high soil moisture and humidity and can be managed through cultural practices like sanitation and drainage as well as fungicide drenches.
Survival and dissemination of phytopathogenic bacteria RitwikSahoo1
The document discusses the survival and dissemination of phytopathogenic bacteria. It explains that bacteria can survive in plant residues, soil, insects, and seeds. Some bacteria like Bacillus and Clostridium form endospores to survive, while others survive as metabolically inactive cells in dry plant tissues. Bacteria can disseminate through various agents like wind, water, soil, seeds, animals, humans, machinery, and transportation. Common examples provided are dissemination of Xanthomonas by wind and various bacteria through rain splash onto neighboring plants.
The document discusses aeromicrobiology, which is the study of airborne microorganisms and their effects on human health and the environment. It defines aeromicrobiology and describes the various microbes that can be found in air, such as viruses, bacteria, fungi, and protozoa. The document also discusses how these microbes can be transmitted through the air and cause diseases in humans and other organisms. It provides examples of common airborne pathogens and the diseases they cause. Furthermore, the document discusses the sizes of airborne biological particles known as bioaerosols and different methods for sampling and analyzing bioaerosols in air, including various impactor and impinger sampling devices.
The document provides an overview of plant disease epidemiology and summarizes key concepts. It defines an epidemic as "a change in disease intensity in a host population over time and space" and explains that epidemiology is the study of disease in populations, including the spread and factors influencing epidemic occurrence. It discusses different types of pathogens like monocyclic, polycyclic, and polyetic pathogens and how they impact disease cycles. Elements that influence epidemics like the host, pathogen, environment, time, and human factors are presented. Disease progress curves and methods of measuring disease in populations are also summarized.
This document provides an introduction to the course PPATH 503: Epidemiology and Forecasting of plant disease. It defines key epidemiological terms like epidemic, defines the basic components of a disease epidemic including the host, pathogen, environment and how they interact. It discusses different types of pathogen cycles including monocyclic, polycyclic and polyetic. It explains disease progress curves and how to measure disease severity and incidence. The importance of epidemiology for disease management is highlighted. New molecular tools for epidemiological studies are also introduced.
The document discusses the disease triangle and disease cycle in plants. The disease triangle illustrates the three factors required for disease: a susceptible host, a pathogen, and a favorable environment. The disease cycle describes the stages a pathogen goes through when infecting a host plant, including inoculation, penetration, infection, invasion, colonization, dissemination, and overwintering/oversummering. It explains each step and how pathogens are able to survive between seasons and continue their life cycles.
air is not a natural environment for microorganisms. Physical & chemical parameters of air do not support the growth and multiplication of microorganisms. Microbes present in the troposphere are actually liberated into air from other sources like soil, water, plant & animal surfaces and human beings. Air acts mainly as a medium for dispersion and transmission of microorganisms. Several infectious diseases are transmitted through air.
- A plant disease develops when a pathogen attacks a plant under favorable environmental conditions. The development of disease is represented by the disease triangle, with the three components being the host plant, pathogen, and environment.
- For a disease to occur, all three components of the disease triangle must be present. The length of each side represents how conducive each component is to disease development.
- The disease cycle refers to the series of events like infection, colonization, reproduction, and survival that allow a pathogen to perpetuate disease over time on or within a host. It spans a growing season or between seasons.
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Aerobiology of Plant Pathogens........................pptx
1. Aerobiology of Plant Pathogens:
Mechanisms, Gradients and Spatial Patterns
Pravin Kumar Bagaria
L-2018-A-58-D
2. • Aerobiology (Greek: aēr = “air” + bios = “life” + logia = “to study”)
- a branch of biology that studies organic particles, such as bacteria, fungal
spores, very small insects, pollen grains and viruses, which are passively
transported by the air (Anonymous, 2017).
- the study of airborne biological particles and their movement and impact on
human, animal and plant health.
- a scientific multidisciplinary biological science, which deals with the source,
release, dispersion, and deposition of different micro-organisms found in the air
and their impact on the ecosystem or life of plants, animals and human beings
(Edmonds, 1979).
3. • 1935 - Term "Aerobiology" by F.C. Meier (USA)
• 1952 - Term 'Air Spora' by P.H. Gregory published in Nature which describe the
airborne pollen grains and fungal spores as:
“The population of air-borne particles of plant or animal origin, which will
here be called the air ‘spora’ (taking the Greek σπορ′α as a word of similar
usage to ‘flora’ and ‘fauna’), contains spores and pollens of various shapes
ranging in size from 100 μm in diameter for some tree pollens to 3-5 μm
with some of the smallest fungus spores” (Gregory, 1952).
4. Spores collected from air of Calcutta
by Cunningham in 1873.
(Figure collected from the book “The Air Spora” by Maureen E. Lacey and
Jonathan S. West, Springer Pub.2006)
• 1873 - In India, first aerobiological study by D.D.
Cunningham (British physician at Calcutta). The
book entitled, ‘Microscopic examination of air’.
• 1933-52 - Prof. K. C. Mehta collected
uredospores of three rusts of wheat and barley.
Reported the presence of teleutospores, smut
spores, Alternaria and different species of
Puccinia.
7. • According to geometry, inoculum source can be classified as
Point source
Individuals or small groups of infected plants;
A diameter of less than 1% of the length of the gradient
Line source
Hedges containing infected alternative host plants or
Strips of a susceptible cultivar
Area source
Infected fields
Although such area sources may become point sources if the distance over which
the gradient is measured is kilometres rather than metres
• According to vertical position, inoculum source may be
Above ground level
Ground level sources
McCartney et al 2006
Source of Inoculum
8. Spore liberation/ discharge (Take off)
(process of detachment of spores from the spore-bearing structure)
I. Active Spore Discharge in Fungi: Spores may be violently discharged by the
mechanisms like:
(i) Bursting of spore-producing structures
(ii) Sudden changes in shape of turgid spores or of turgid structures associated with
the spores;
(iii) Rapid twisting movements produced as a result of drying in filamentous
sporangiophores or by hygroscopic movement;
(iv) Sudden breaking of tensile water in conidia or conidiophores, distorted on drying,
which are thereby permitted to return to their original form; and
(v) Impaction
9. II. Passive Spore Liberation:
(i) Liberation of Dry Spores - Through rain drop and winds (Mechanical momentum
and Blowing away:- Rust uredospore)
(ii) Liberation of Slime Spores- Through rain drop
• Spores may also be removed from the leaf surface by puffing action of raindrops
• Occurs when the first raindrops fall
• Release of puffball spores from the mature fruiting bodies has a similar action
• Strong gusts of wind or contact with animals can also result in spore puffs
10. I. Active Spore Discharge in Fungi:
A-C - Trigger device in Sphaerobolus sp.
D-H – Syringe device, D-E in Sphaerotheca sp., F-J in
Pilobolus sp.
Drop-excretion mechanism
A - Basidiospore discharge.
B-E – Successive stage in the fluid drop excretion
and basidiospore discharge
11. I. Active Spore Discharge in Fungi:
A-B – Change in condition of turgid structures in Sclerospora sp.
C-F – Hygroscopic movements of sporangiophores in
Peronospora tabacina.
G-K – Gas bubble mechanism in Deightoniella torulosa
Spore liberation mechanism by impact of rain
A-F – In Niduriales
G-J – Lycoperdon sp.
12. Dispersal of Plant Pathogen
• Transport of spores or infectious bodies, acting as inoculum, from one host to
another host at various distances resulting in the spread of the disease
OR
• Displacement of a plant pathogen from its place of production or origin to a
suitable place where it can grow/ established
• Fundamental step for repeated cycles of infection and multiplication
• Dependent on the method of discharge by individual taxa as well as
environmental factors, such as temperature, humidity, and wind speed
• Strong gusts disperse spores even when the average wind speeds are too low
• Wind dispersal is promoted by warm and dry weather
• Peak during afternoon hours, when humidity is low and wind speeds are
increased
McCartney et al 2006; Levetin, 2016
13. Mechanism of Spore Dispersion
• Active dispersion
• Passive dispersion:-
Dispersion by Wind
High temperatures & low relative humidity
Long range dissemination – b/w fields or regions
Dispersion by Rain splash
Also provides moisture required for germination
Short range dissemination – within plant or nearby
plants
14. Movement in the Atmosphere
• Wind is the major factor, with gusts and lulls affecting
take off, transport, and deposition
• In a crop, spores have to pass from the laminar layer
close to the leaf surface into the turbulent layer
within the crop
• Gusts and turbulence enhance spore removal from
leaves by sweeping away the layer of slow-moving air
next to the leaf surface
• Spores must pass through the crop boundary layer
surrounding the crop
Levetin 2016
The ground is black.
Above ground is thin layer of laminar air (L)
and on top of this turbulent air (T).
Discharged spores are disseminated by wind.
15. • Carried by wind, spores are transported both horizontally and vertically
• Horizontally, spores carried for thousands of kilometers, dispersing pathogens into new
areas
• Vertically, carried upward by convective activity or thermals and have been recovered
from altitudes higher than 5,000 m
• Rain splash can also propel spores into the atmosphere, and it is second to wind in
importance as a means of pathogen dispersal
• Splash-borne spores or bacteria are usually produced in mucilage which inhibits their
direct removal by wind
• The first raindrops dissolve the mucilage and leave a spore suspension available for splash
dispersal by additional raindrops
Levetin 2016
16. Survival in the Atmosphere
• Fungal spores are more resistant to environmental stress compared to parent hyphae.
• Exposure to harmful radiation, extremes of temperature and humidity can decrease the
viability.
• Changes in relative humidity, often caused by changing wind speeds, may affect survival,
especially for thin-walled spores, which may easily plasmolyze.
• Desiccation risks are more during the daytime and close to the ground.
• At night and at high altitudes, conditions are less stressful.
• Thin-walled colorless spores may be more vulnerable compared to pigmented spores.
• Low temperatures in the upper atmosphere may be preservative and protect spores
from UV damage
Levetin 2016
17. Scale of spore/ disease spread
Microscale,
Mesoscale, or
Synoptic scale Levetin, 2016
Scales of Pathogen Dispersal Scales of air turbulence
Mahaffee and Stoll, 2016
18. Microscale spread
• Limited to less than a few hundred meters within one field and occurs within one
growing season
• Roughly corresponds to a zero-order epidemic
• The focus begins with a single successful propagule causing an infection and creating a
lesion
• After several generations of localized pathogen spread for polycyclic diseases, which
produce many generations of inocula and many cycles of infection during a single growing
season, the focus may reach a detectable size
• In an annual crop, these are about 1 m in diameter around the initial source of infection
• If growing conditions are unsuitable for the pathogen, the focus may stop expanding or
even disappear with new growth in the canopy. Levetin, 2016
19. Mesoscale spread
• However, when conditions are favorable for the pathogen, the disease will spread
• As the primary focus continues to expand, secondary foci and later tertiary foci appear.
• This continued focal spread over a larger area is considered mesoscale spread and
corresponds to a first-order epidemic
• This may be restricted to one field but may spread over many fields or up to an area
several hundred square kilometers or even over part of a continent during a single
growing season
Levetin, 2016
Synoptic or Macroscale spread
• Synoptic or macroscale spread occurs when the epidemic progresses for several years and
spreads over an area of several thousand square kilometers
• This is also referred to as a second-order epidemic.
• This pandemic may cover a whole continent after a certain number of years
20. Spore Landing (Deposition)
• Sedimentation
• Impaction
• Inpingement
• Filtration
• Boundary layer exchange & turbulence
• Rain deposition
• While airborne – spores touch wet surfaces – get
trapped
Spore movement is influenced by
• Gravity
• Brownian motion
• Electric charge
• Temperature
• Inertial precipitation and impaction
• Periodicity of wind
Diurnal
Nocturnal
• Turbulence in air
Levetin 2016
21. Dispersal by wind/ rain-splash and spore deposition gradients
• Individual spores released from the same source under the same wind conditions follow
different paths and travel different distances.
• With disperse downwind, spore concentrations in the air decrease referred to as
‘concentration gradients’.
• The turbulent nature of wind causes a dilution in the concentration of a spore plume.
• Consequently, dispersal gradients for splash-dispersed spores are generally much shorter
than those for wind-dispersed spores.
• Crop canopy structure affects the deposition of splashed droplets and the potential for
spread by secondary splash.
• Thus, duration of exposure to rain and rain intensity may modify ‘primary splash’
gradients.
• Primary dispersal is dominant at the beginning of a rain shower.
• However, as rain duration continues, secondary spread may begin to be important.
• If the rain persists for sufficient time to deplete the source, inoculum deposited may be
lost by wash-off.
McCartney et al 2006
22. SPORE DEPOSITION AND DISEASE GRADIENTS
• For both wind and splash-dispersed plant pathogen inoculum, deposition rates decrease with
distance away from the inoculum source
• The disease pattern that develops will also show a decrease in disease with increasing distance
away from the source, i.e. a disease gradient
• Disease gradients can also result from gradients in host or environmental factors
• Background inoculum from a large number of distant sources produces a uniform distribution of
disease with distance across a crop
• Vertical disease gradients can also be observed when inoculum sources are at ground level
• Disease gradients produced by splash-dispersed inoculum are usually steeper than those
produced by wind-dispersed inoculum
• Secondary spore dispersal can flatten primary spore dispersal and disease gradients with time
McCartney et al 2006
23. • Monocyclic diseases produce only primary disease gradients
• Over long periods of time the disease gradients gradually become less steep
• Disease gradients with polycyclic diseases are first observed in a crop as primary disease
foci resulting from a single lesion
• Initially disease gradients are steep but spores which escape from the crop canopy soon
establish secondary foci
• Primary disease gradients become more shallow as foci expand and, with the expansion
of secondary foci
• Initial horizontal gradients are caused by wind-dispersed primary inoculum but
subsequent horizontal spread and vertical spread up the crop canopy is achieved by
splash-dispersed secondary inoculum
• Gradients from sources above ground level are generally less steep than those from
ground level sources
• The same spore dispersal mechanism could account for steep gradients close to a
source and shallow gradients farther away McCartney et al 2006
24. Measurement of gradients (spore dispersal or disease gradient)
Spore numbers per m3 (spore concentration gradient) or
Spore numbers per m2 (spore deposition gradient) (C) or
Disease incidence or severity (Y ) at different distances (x)
• Spore numbers can be estimated with artificial samplers
• Spore deposition gradients can be measured by passive samplers (horizontal slides under
rain-shields for wind-dispersed spores) or beakers for splash-dispersed spores
• Concentration gradients can be measured with volumetric samplers
• The disease component of disease gradients has been measured as numbers of lesions,
numbers of infected leaves, numbers of infected plants, the percentage leaf area affected or
the percentage of the population of plants which is affected
McCartney et al 2006
25. Spatial patterns
• Spatial patterns of disease may be quite different from the spore dispersal
patterns
• Because spore dispersal is a short term phenomenon compared to most other
stages of disease development
• Spatial patterns are the result of many individual dispersal events from many
sources over periods of days or even weeks
• Disease patterns and epidemic size are strongly influenced by dispersal patterns
• Spatial patterns foci are often circular but strongly affected by wind, may become
comet- or V-shaped.
• Foci generally have a constant radial expansion, with the rate varying with the
scale of the infection from a few centimeters per day for a localized infection to
hundreds of kilometers per year for a pandemic
McCartney et al 2006
26. • Trajectory analysis - a standard tool in the study of air movement and it tracks the
movement of air parcels using information on wind fields and atmospheric temperature
structures
• Potential long distance aerial transport uses air parcel trajectory analysis to establish links
between source and receptor regions
• Backward trajectory analysis is frequently used to trace the previous movement of a
spore-laden parcel of air and locate the inoculum source
• Once the source is identified, forward trajectories are used to indicate further potential
areas of fallout.
• Various dispersion models have been used to trace the movement of spores from
dissemination at a source to deposition at a sink by calculating trajectories based on upper
air winds, temperature, and other parameters.
McCartney et al 2006; Levetin 2016
27. NASA’S Balloon Missions
Exposing Microorganisms in the Stratosphere 1 (E-MIST 1) - 2014
• For studying bacteria in Earth’s stratosphere (about 10 to 31 miles)
at NASA’s Kennedy Space Center, Florida
• A radiation-tolerant strain of bacteria (Bacillus pumilus) was
carried inside the E-MIST payload (mounted on large balloon, New
Mexico)
• Purpose: To expose bacterium to harsh conditions of the
stratosphere (5 hours)
• Result: Data could be collected within the stratosphere
Exposing Microorganisms in the Stratosphere 2 (E-MIST 2) – 2015 October
• Exposed bacterium to Mars surface-like conditions (extremely cold, dry air, harsh ultraviolet
radiation and low air pressure) to test how well they could survive
• Result: After 8 hours of exposure, 99.999% of the bacteria were dead, damaged, or destroyed
beyond the point of being able to regrow (19 miles above sea level)
28. Microbes in Atmosphere for Radiation, Survival and Biological Outcomes Experiment (MARSBOx) –
2019, Sept
• This aerobiology research experiment was flown on a NASA scientific balloon mission launched from
Fort Sumner, New Mexico (6.5 hours and altitude of 110,000 feet)
• Purpose: To measure effect of ionizing radiation conditions in the stratosphere
Carried 9 different types of microorganisms (bacteria & fungi) in dormant state
• Results: most of bacteria died, but fungal spores were able to better withstand the harsh
environment at >20 miles up
Aircraft Bioaerosol Collector (ABC) - (installed NASA’s C-20A aircraft)
• ABC - an instrument, custom built at NASA’s Armstrong Flight Research Center
• Purpose:
To capture and seal up bioaerosol samples in troposphere and in lower stratosphere
(as high as 8.5 miles)
To tackle difficult challenge of sampling and studying microorganisms at extreme
altitudes during ascent, descent and sustained cruises
To discover airborne bacterial diversity at different levels
• Result: a similar distribution of bacteria in the atmosphere at all altitudes
29. Periodicity of airborne concentration of
Botrytis cinerea conidia above a
strawberry field monitored using rotating
arm sampler and a qPCR assay for
quantification of conidia
Carisse 2016
30. Dynamics of B. cinerea airborne conidia monitored in raspberry
(a), strawberry (b), and grape (c) plantings in Canada (2010)
Progress of Botrytis fruit rot in strawberry plantings with various
cultivars at the Agriculture and Agri-Food Canada experimental
farm in 2010 Carisse, 2016
31. Fungal spores were identified and quantified in the air of Bratislava during the 1-year
period (2016) using a Burkard 7-day volumetric aerospore trap.
32. Spore calendar for Bratislava Exponential classes (spores/m3):
a 1–5, b 6–10, c 11–25, d 26–50, e 51–100, f 101–500, g 501–1000, h
> 1000
Relative contributions (% of total spore
concentration) of the major spore types in
the air of Bratislava
Annual total spore count (spores/m3)-
836,418 fungal spores belonging to 53
spore types in Bratislava during 2016
Scevkova and Kovac 2019
33. Monthly variations in the spore concentrations of the major
fungal taxa and total fungal spores in the air of Bratislava
Prevailing weather conditions (mean, maximum and
minimum air temperature, absolute air humidity and
rainfall)
Scevkova and Kovac, 2019
34. Airborne spores of Cladosporium spp. were sampled on the roof, 21 m above sea level in
Viborg during 115 days, 31 May–22 September 2015, on the 48 × 14 mm slides using a
Hirst-type spore trap
35. Olsen et al 2019a
Daily average concentrations of Cladosporium spp. at
Viborg station during 31 May- 22 September 2015 (n =
115), mean daily average concentration over the period:
1897 spores m-3. Red vertical lines confine the longest
period of high concentrations. Peak daily average
concentration occurred on 16 August (13,553 Spores m-3)
Cladosporium spp. diurnal distribution at Viborg
station on the days with daily average
concentrations: above 3000 Spores m-3 (green line,
n = 21), above 3000 Spores m-3 without considering
14 August and 16 August (red line, n = 19), below
3000 Spores m-3 (blue line, n = 94)
36. The episode of 13–25 August 2015:
a 3-h time series of Cladosporium spp. concentrations at Viborg (blue) and Copenhagen (red) stations, daily
precipitation at Foulum station (green) ;
b Lines represent 48-h back trajectories for the period of 13–25 August: green on 13 August and 25 August, red
on the day with maximal concentration, i.e. on 16 August, black on the other days within the period;
Olsen et al 2019a
37. Burkard volumetric spore sampler.
Compared the concentrations of airborne Alternaria spores and the patterns of air mass
transport using HYSPLIT model between Copenhagen and Viborg with the main focus on
the days with daily average spore concentrations >100 s m-3 (high concentration days).
38. Monthly spore integrals of airborne Alternaria spores
(2012–2015) for all days and for high concentration days
(with daily average concentration > 100 s m-3); CPH
Copenhagen, VIB Viborg
Daily time-series of airborne Alternaria spp. At
Copenhagen and Viborg stations (2012–2015)
Olsen et al 2019b
39. Clusters and cluster means of 48-h back-trajectories for the Copenhagen station on the days with daily average
concentration:
a > 100 s m-3 (high days) and b <100 s m-3 (low days)
Olsen et al 2019b
40. Clusters and cluster means of 48-h back-trajectories for the Viborg station on the days with daily average
concentration:
a > 100 s m-3 (high days) and b <100 s m-3 (low days)
Olsen et al 2019b
41. Air samples were collected using settle plate method. Petri plates containing potato
dextrose agar (PDA), Martins rose bengal agar (MRBA) and Czapek’s Dox agar medium
supplemented with chloramphenicol (250 mg/ml) were used for collecting the air samples.
The rhizosphere, air and phylloplane were dominated by Rhizopus stolonifer.
Pestalotiopsis disseminata is one of the major pathogens of Som and was found highest in
aerosphere followed by phyllosphere.
42. Fungal diversity in air in the Som plantation area
Ray et al 2019
Common population among the four environments:
rhizosphere, non-rhizosphere, air and phylloplane
43. Two qPCR TaqMan assays were developed to detect pathogen DNA: the first used a generic
probe to detect Phytophthora spp., and the second was based on a specific probe for
detecting P. ramorum and P. lateralis.
All samples tested positive for the genus Phytophthora, although P. ramorum and P.
lateralis were not detected.
44. Migliorini et al 2019
Seasonal variation in DNA quantities
(pg/µl) of Phytophthora species
(black line) shown with
meteorological variables, i.e.
rainfall (mm, a);
relative humidity (%, b);
maximum, minimum and mean air
temperature (°C, c); and
extremes of air temperature (°C, d)
45. Conclusion
• A wide variety of plant pathogens, including viruses, bacteria, oomycetes, and fungi, are
dispersed through the atmosphere
• When conidia are produced on a source near the ground or in the lower canopy, they are
exposed to slow wind speeds, low turbulence, and rapid rates of sedimentation,
conditions that are conducive to short-distance transport
• When they are deposited on a susceptible host, infection can
occur, and when environmental conditions are favorable, the resulting disease spread
may lead to widespread crop loss
• Measurement of disease or spore gradients can be extremely important for identifying
sources of disease, for identifying inoculum dispersal mechanisms, for assessing the
effectiveness of some disease control strategies and for interpreting the results of field
experiments
• Long range dispersal favours more widespread epidemics and increases the likelihood of
disease persistence
• A thorough understanding of the role of the aerobiological pathway in pathogen
dispersal is necessary for the management and control of disease
• Knowledge of aerobiology can help researchers and farmers to assess, predict and
decrease the effects of epidemic pathogens
Editor's Notes
Aerobiology (from Greek ἀήρ, aēr, "air"; βίος, bios, "life"; and -λογία, -logia) is a branch of biology that studies organic particles, such as bacteria, fungal spores, very small insects, pollen grains and viruses, which are passively transported by the air.[1]
Aerobiologists have traditionally been involved in the measurement and reporting of airborne pollen and fungal spores as a service to allergy sufferers.[1]The first finding of airborne algae took place in Germany in 1910.[2]
1935 - The term "Aerobiology" by F.C. Meier (USA) for the studies of air spora like airborne fungal spores, pollen grains and other microorganisms.
1952 - Term 'Air Spora' by P.H. Gregory published in Nature which describe the airborne pollen grains and fungal spores as:
1873 - In India, first aerobiological study was carried out by D.D. Cunningham, a British physician at, Calcutta. This was the first report on aerobiological work in India, was published in the book entitled, „Microscopic examination of air‟.
1933-52 - Prof. K. C. Mehta collected uredospores of three rusts of wheat and barley from 62 different parts of country in different altitude. He reported the presence of teleutospores, smut spores, Alternaria and different species of Puccinia.
Most of the aerobiological work is carried out with reference to the Aerobiological Triangle described by a pathway of five main steps viz.,
Chapter 9:- General aerobiological process diagram (Isard et al. Principles of the atmospheric pathway for invasive species applied to soybean rust. 2005. Copyright, American Institute of Biological Sciences). Isard SA, Russo JM, Ariatti A. 2007. The Integrated Aerobiology Modeling System applied to the spread of soybean rust into the Ohio River valley during September 2006. Aerobiologia 23:271–282.
Isard, S. A., Gage, S. H., Comtois, P. and Russo, J. M., 2005: Principles of the atmospheric pathway for invasive species applied to soybean rust. BioScience 55, pp. 851-861.
Conidia of Blumeria (Erysiphe) graminis f.sp. hordei (cause of barley powdery mildew), which form in chains above the leaf surface, were released by wind speeds greater than 0.5 m s (Hammett and Manners, 1974) and conidia of Drechslera maydis (cause of southern leaf blight of maize) were removed only by wind speeds of more than 5 m s (Aylor, 1975). The wind intermittency observed in crop canopies probably plays an important role in spore removal because it is only in gusts that wind speeds are large enough to remove spores
However, Aylor (1987) suggests that deposition will determine the shape of concentration gradients only when wind speeds in the canopy are low and when turbulence is slight. Thus, for spores released in gusts the effects of enhanced turbulence on diffusion may be much greater than the enhanced deposition byinertial impaction.
Conidia of Blumeria (Erysiphe) graminis f.sp. hordei (cause of barley powdery mildew), which form in chains above the leaf surface, were released by wind speeds greater than 0.5 m s (Hammett and Manners, 1974) and conidia of Drechslera maydis (cause of southern leaf blight of maize) were removed only by wind speeds of more than 5 m s (Aylor, 1975). The wind intermittency observed in crop canopies probably plays an important role in spore removal because it is only in gusts that wind speeds are large enough to remove spores
However, Aylor (1987) suggests that deposition will determine the shape of concentration gradients only when wind speeds in the canopy are low and when turbulence is slight. Thus, for spores released in gusts the effects of enhanced turbulence on diffusion may be much greater than the enhanced deposition byinertial impaction.
I. Active Spore Discharge in Fungi: Spores may be violently discharged by the mechanisms like: (i) The bursting of spore-producing structures; (ii) Sudden changes in shape of turgid spores or of turgid structures associated with the spores; (iii) Rapid twisting movements produced as a result of drying in filamentous sporangiophores or by hygroscopic movement; (iv) Sudden breaking of tensile water in conidia or conidiophores, distorted on drying, which are thereby permitted to return to their original form; and (a) by impaction. The distance of projection of spore discharge depends on the initial velocity of the projective and on its size, shape and density.
Active Spore Discharge in Fungi: Spores may be violently discharged by the mechanisms like: (i) The bursting of spore-producing structures; (ii) Sudden changes in shape of turgid spores or of turgid structures associated with the spores; (iii) Rapid twisting movements produced as a result of drying in filamentous sporangiophores or by hygroscopic movement; (iv) Sudden breaking of tensile water in conidia or conidiophores, distorted on drying, which are thereby permitted to return to their original form; and (a) by impaction. The distance of projection of spore discharge depends on the initial velocity of the projective and on its size, shape and density.
The active discharge of basidiospores of Hymenomycetes is associated with the secretion of a small drop of liquid and the spores are discharged by drop-excretion mechanism (Fig. 259).
Although still vulnerable to certain types of environmental damage while airborne
; spores have even been reported to germinate in the clouds
Spores may also serve as condensation nuclei for rain.
Because of the erosion of the ozone layer in the upper atmosphere, the effects of UV radiation on fungal spores have been the focus of several studies.
Scientists are interested in possible decreases in spore germination, mycelium development, and spore formation caused by the radiation (53, 54).
Despite environmental hazards, many spores are able to survive long-range transport, but the percentage of viable spores that actually reach a target and cause infection is low.
Levetin, 2016Aerobiology of Agricultural Pathogens
Levetin, 2016Aerobiology of Agricultural Pathogens
Levetin, 2016Aerobiology of Agricultural Pathogens
However, the proportion of conidia that escape the canopy, assuming that the source is within it, depends on the equilibrium between deposition and turbulent transport and on the vertical position of the inoculum source.
When conidia are produced on a source near the ground or in the lower canopy, they are exposed to slow wind speeds, low turbulence, and rapid rates of sedimentation, conditions that are conducive to short-distance transport.Spores can be deposited on the crop surface by sedimentation, impaction, boundary layer exchange, turbulence, or electrostatic deposition and through raindrops
Loss of viability may occur due to desiccation
Winds are highly variable in both time and space.
This variability or turbulence causes individual spores, released from the same source under the same wind conditions, to follow different paths and travel different distances.
Therefore, as spore plumes disperse downwind from sources their concentrations in the air decrease.
The decreases in concentration are frequently referred to as ‘concentration gradients’.
Mean wind speed characteristics above crops are fairly well understood; wind speeds increase with height depending on the nature of the crop (height, architecture, density) and the stability of the atmosphere (temperature profile).
For example, in neutrally stratified atmospheres when buoyancy effects can be neglected, over open terrain with uniform vegetation, wind speed u(z) increases logarithmically with height z :
The wind profile is logarithmic only with well formed surface boundary layers over large uniform areas.
Wind profiles near obstructions such as hedges or near changes in terrain, for example woodland boundaries, may be more complex
Monocyclic diseases produce only primary disease gradients, in which all the lesions arise from the same inoculum source. For example, gradients of the phoma leaf spot stage of stem canker (causal agent Leptosphaeria maculans) can be produced by the wind-borne ascospores in winter oilseed rape crops in the autumn (Gladders and Musa, 1980). However, spores of pathogens causing monocyclic diseases may be released over long periods of time so that the disease gradients gradually become less steep as the growing season progresses. This may explain why gradients of wheat eyespot in inoculated winter wheat plots became less steep with successive observations, although removal of inoculum suggested that there was no secondary disease spread (Rowe and Powelson, 1973).
Many economically important crop diseases are caused by foliar fungal pathogens, for which the main routes of dispersal are wind-borne or splash-borne spores.
The scale of dispersal by these processes ranges from a few centimetres for some the wind.
For foliar pathogens, disease spread is the direct consequence of spore dispersal, although spatial patterns of disease may be quite different from the spore dispersal patterns which cause them.
This is partly because spore dispersal is a short term phenomenon compared to most other stages of disease development.
Disease patterns are often the result of many individual dispersal events from many sources over periods of days or even weeks.
For example, conidia of Pyrenopeziza brassicae, the cause of light leaf spot on oilseed rape (Brassica napus ssp. oleifera), take about 18 hours to germinate under optimum conditions, while splash dispersal of conidia over typical distances of 20-30 cm takes less than one second and wind dispersal of ascospores of P. brassicae over 100 m takes 1-2 minutes. Even for long distance dispersal, such as for tobacco blue mould (www.ces.ncsu.edu/depts/pp/bluemold/) that can spread from Cuba to the southern USA (Aylor, 1999) or cereal rusts in the USA or India (Hamilton and Stakman, 1967; Nagarajan and Singh, 1990), dispersal events (hours or days) may be short compared with infection processes.
The HYSPLIT (hybrid single-particle Lagrangian integrated trajectory) model has been widely and successfully used to track the movement of several pathogens and predict the occurrence of disease outbreaks
Back-trajectory analysis revealed long distance dispersal of exotic Bacillus bacteria 1800 km from the black sea to Sweden, where the species was isolated from red pigmented snow.
Trajectory modelling account for large scale movement of air parcels due to wind direction changes and track air movements over large distances.
Several studies of potential long distance aerial transport of plant pathogens have used air parcel trajectory analysis to establish links between source and receptor regions.
Trajectory analysis is a standard tool in the study of air pollutant movement and it tracks the movement of air parcels using information on wind fields and atmospheric temperature structures.
Back-trajectory analysis of wind contributed to evidence for long distance dispersal of exotic Bacillus bacteria 1800 km from the black sea to Sweden, where the species was isolated from red pigmented snow.
Trajectory modelling can account for large scale movement of air parcels due to wind direction changes and track air movements over large distances.
A radiation-tolerant strain of bacteria called Bacillus pumilus was carried inside the E-MIST payload, which was equipped with power, a control board for self-controlled operations, customizable electronics, environmental controls and sensors.
The second Exposing Microorganisms in the Stratosphere mission, E-MIST 2, exposed the bacterium Bacillus pumilus SAFR-032 to Mars surface-like conditions to test how well they could survive. The E-MIST 2 payload was launched from New Mexico on a NASA high-altitude balloon and spent eight hours within the stratosphere at close to 19 miles above sea level.
Samples were parachuted back to Earth for analysis, and the science team found that, after the eight hours of exposure, 99.999% of the bacteria were dead, damaged, or destroyed beyond the point of being able to regrow.
The undamaged few showed small variations in DNA compared to samples of the same bacteria that stayed on the ground. Fully understanding the implications of these results will require further study, but the initial discoveries from the mission have provided significant insights for aerobiology, Earth ecology and astrobiology. The E-MIST 2 mission launched in October 2015.
The MARSBOx experiment for aerobiology research was flown on a NASA scientific balloon mission launched from Fort Sumner, New Mexico, on Sept. 23, 2019.
The mission lasted 6.5 hours and reached a sustained altitude of 110,000 feet. MARSBOx measured the ionizing radiation conditions in the stratosphere using onboard instruments.
It also carried nine different types of microorganisms, including bacteria and fungi, in a dormant state that can protect them from many tough environmental conditions.
Preliminary results from the flight show that most of the bacteria died, but the fungal spores were able to better withstand the harsh environment at more than 20 miles up.
Aircraft Bioaerosol Collector (ABC)The Aircraft Bioaerosol Collector, or ABC, is an instrument that was custom built at NASA’s Armstrong Flight Research Center to capture and seal up bioaerosol samples from upstream air flowing around a moving aircraft. The ABC can collect samples while flying as high as 8.5 miles, and tackles the difficult challenge of sampling and studying microorganisms afloat at extreme altitudes.
The first mission to use the instrument, ABC-1, was led by members of the Aerobiology Lab at NASA Ames and was designed to discover the types of airborne bacteria present at different levels in the troposphere, the lowest layer of Earth’s atmosphere, and in the lower stratosphere, the layer above the troposphere. The research team installed the ABC on NASA’s C-20A aircraft. The research jet was then flown over regions of California and the western U.S., and the ABC collected air samples during ascent, descent and sustained cruises at altitudes up to almost 7.5 miles. Scientists were surprised to discover a similar distribution of bacteria in the atmosphere at all altitudes studied.
In flower-infecting Botrytis pathosystems, the seasonal progress of airborne B. cinerea in berry plantings is characterized generally byan airborne conidia concentration that is initially low but then increases during fruit ripening and until the last fruit harvest
Fungal spores were identified and quantified in the air of Bratislava during the 1-year period (2016) using a Burkard 7-day volumetric aerospore trap.
Spectrum and quantity of fungal spores were measured from January to December 2016 by Hirst type volumetric aerospore trap (Burkard model).
The sampler was placed on the roof of the Department of Botany, Comenius University in Bratislava, in northwest part of the city at the height of 10 m above ground level.
Jana Scevkova and Jozef Kovac, 2019
Aerobiologia
Fungal spores were identified and quantified in the air of Bratislava during the 1-year period (2016) using a Burkard 7-day volumetric aerospore trap. The total annual spore concentration recorded during this period was 836,418 spores/m3, belonging to 53 fungal spore types. The fungal taxa contributing the highest concentration of spores were Cladosporium (71.88% of the total), Coprinus (8.84%), Leptosphaeria (3.88%), Ganoderma (3.43%) and Alternaria (2.79%). Fungalspores peaked during summer and autumn months (June–October) and declined from November to March. The maximum monthly total spore concentration (153,342 spores/m3) was recorded in July, while the minimum (1381 spores/m3) in January. Spore concentrations of most analysed airborne fungal taxa were positively associated with air temperature and/or negatively associated with relative air humidity either throughout the year or only in summer. Cladosporium spore concentration was positively related with the wind speed, whereas the association between Ganoderma spore concentration and wind speed was negative. Spores of Leptosphaeria showed significant positive association with relative air humidity and significant negative association with sunshine duration in summer. Knowledge of seasonal patterns of the type and number of spores in the air
Airborne spores of Cladosporium spp. were sampled by the Asthma and Allergy Association on the roof of Regionshospitalet, 21 m above sea level in Viborg (56270N 9240E) during 115 days, 31 May–22 September 2015, on the 48 9 14 mm slides using a Hirst-type spore trap
Yulia Olsen et al 2019
Aerobiologia (2019) 35:373–378
Daily average concentrations of Cladosporium spp. at Viborg station during 31 May- 22 September 2015 (n = 115), mean daily average concentration over the period: 1897 spores m3. Red vertical lines confine the longest period of high concentrations. Peak daily average concentration occurred on 16 August (13,553 Spores m3)
The diurnal cycle of Cladosporium spores (Fig. 3) on the days with daily average concentrations above 3000 Spores m-3 had a maximum between 08:00 and 10:00. However, after excluding the high concentrations on 14 August and 16 August, the diurnal distribution reflected elevated concentrations between 06:00 and 20:00 (Fig. 3).
Elevated day time concentrations in Viborg on the days with daily average concentrations exceeding the threshold also indicate the local character of the sources. Eighteen (out of 21) days with daily average concentration above 3000 Spores m-3 occurred in August, contributing up to 80% of August SIn. The peak daily average and 3-h concentrations were measured on 16 August.
During the 11 days, 14–24 August, the air masses were arriving from the East and South East, i.e. originating in the areas in Poland, the Baltic countries, and north-west Russia, passing over the Baltic sea and southern Sweden (Fig. 2b). Conversely, on 13 August and on 25 August, the wind directions were distinctively different with the air masses arriving from the North–West and South–West (Fig. 2b). In the course of those 11 days, the corresponding daily average concentrations at the Copenhagen station were lower than at the Viborg station.
High airborne Alternaria spore concentrations measured in eastern Denmark have been associated with local agricultural sources. However, the density of agricultural areas is highest in western Denmark. This is the first report of airborne Alternaria spore concentrations obtained with Burkard volumetric spore sampler in western Denmark, Viborg. We compared the concentrations of airborne Alternaria spores and the patterns of air mass transport using HYSPLIT model between Copenhagen and Viborg for the seasons 2012–2015, with the main focus on the days with daily average Alternaria spore concentrations C 100 s m-3 (high concentration days).
local sources cause the main load of airborne Alternaria spore concentrations in Denmark; We found increased shares of trajectories coming from SouthEast on the high concentration days and increased shares of trajectories coming from the West and North-West on the days with concentrations below 100 s m-3 for both stations. July and August had the highest spore integrals matching the periods of grain harvesting in Denmark.
Muga silkworm is endemic to North-East India. The quality of primary host plant, i.e. Som. (Persea bombycina Kost.), greatly affects the quality of cocoon and silk production. Som is susceptible to different foliar diseases caused by fungi, which can reduce the yield of leaf from 13.8 to 41.6% annually
Air samples were collected using settle plate method described by Aneja (2012). Petri plates containing potato dextrose agar (PDA), Martins rose bengal agar (MRBA) and Czapek’s Dox agar medium supplemented with chloramphenicol (250 mg/ml) were used for collecting the air samples. The rhizosphere, air and phylloplane were dominated by Rhizopus stolonifera. Pestalotiopsis disseminata is one of the major pathogens of Som and was found highest in aerosphere followed by phyllosphere.
Ray et al 2019
Aerobiologia
In this study, spore trap monitoring was applied to provide a proof of concept for the use of qPCR to detect Phytophthora in aerial samples and provide valuable information for epidemiological studies in nurseries. Two qPCR TaqMan assays were developed to detect pathogen DNA: the first used a generic probe to detect Phytophthora spp., and the second was based on a specific probe for detecting P. ramorum and P. lateralis. All samples tested positive for the genus Phytophthora, although P. ramorum and P. lateralis were not detected.
In late spring and in autumn, two main peaks of Phytophthora sporulation were observed. Peaks were preceded by rainfall, high relative humidity, and mild temperature. From midMay to the end of August, Phytophthora DNA detected in the air increased with relative humidity, while it decreased with increasing mean temperature. There was also a positive correlation between Phytophthora DNA detected and rainfall in the same period. No significant correlations between Phytophthora DNA and temperature or rainfall were found from the end of August to December. Our results are in agreement with those obtained with classical diagnostic methods based on microscopy, but the approach used here enabled rapid detection and relative quantification of the target organisms, thus assisting in the implementation of disease management strategies
Migliorini et al 2019
Aerobiologia (2019) 35:201–214