Lecture 0 • We can generate immunity without inducing disease
vaccination
• Pasteur’s cholera vaccine: Pasteur isolated the bacteria from
sick chickens and grew it in the lab. One of his lab assistants
forgot to inject the chickens with a fresh batch of the bacteria
• Fusarium oxysporum causes wilt on banana. before going on vacation. They used old aged bacterial
• Wheat head blight mycotoxins are produced (deadly). Different culture on healthy chickens Chickens didn’t die like usual.
species of Fusarium cause different things. When they were injected with fresh bacteria, they still didn’t
• Sustainable crop disease strategies get sick.
• Stacking R-genes (resistance genes) from wild relatives (enable • Weakened, attenuated bacteria made the chickens immune
ETI): R-genes recognize specific pathogen effectors and trigger to disease.
a strong immune response called Effector-Triggered Immunity • herd immunity = some threshold of the population should be
(ETI). Stacking means introducing multiple R-genes into a single vaccinated so the virus does not spread.
crop to make it harder for the pathogen to evade recognition. • HIV jumps from one species to the other
Wild plant relatives often have diverse R-genes that are not • Problems with HIV vaccine: 1. safety
present in cultivated crops.
• you do not want to vaccinate with attenuated HIV particle,
• Deletion of a susceptibility (S-) gene (prevent ETS): S-genes because HIV can mutate very fast --> what if they get infected
actually help the pathogen during infection. Effector-Triggered with HIV?
susceptibility occurs when effectors supress the plant’s
immunity using S-genes. Knocking out S-genes means the • HIV mutates very fast; will the person be protected against
pathogen can’t manipulate the plant as easily. these?
• Increased ROS-production and HR (strengthen direct defense • Challenges in COVID-19 vaccination: problem is not solved
mechanisms): Plants produce ROS to kill or limit the spread of • in some individuals the vaccination causes antibody
pathogens. Hypersensitive response is a form of programmed enhanced disease. Explosion of the immune response.
cell death around the infection site – a way of isolating the Increased inflammation.
invader. We can boost this up. • Immune therapy in cancer tries to reactivate cells that can
• RNAi (gene silencing in the pathogen) specifically kill cancer cells. Specific.
• Diseases on animals affect us We have less food
• Plants release energy into the soil, to feed and select microbes
around the roots. What are the benefits? These microbes can • Zoonosis: a new virus in the wildlife populations is a potential
increase stress resilience or nutrient uptake. new virus in the human populations.
, Hemi-biotroph: Lives on living
Lecture 1 – uses specialized structures (hau
has a necrotrophic phase (feed
from killed cells). When the dise
• Healthy plant: it forms a necrotrophic phase
• Sick plant: Leaf blight, leaf discoloration, predation, Oomycetes: Oomycetes produces sp
leaf spots, wilting, abnormal outgrowth, root rot, cysts produce spores. The spores are
and root knots Sporangium is formed it can germina
leaf, but it can also form inside zoospo
• Biotic plant disease: fungi, bacteria, viruses, spores with flagella, they can swim in
nematodes. the leaves. when that happens hau
and the pathogen can progress into t
• Abiotic plant disease: draught, flooding, heat/ cold, the deeper layer of the leaf tiss
nutrition, pollution biotrophic phase and then the necrotr
• Many kind of organisms cause plant disease.
Nematodes can penetrate the worm cells and inject Pests and diseases cause major crop losses. The oom
sexual life
their needle into the plant cell, causing disease. Biotic plant disease:
Necrotro
• Pests on plants. They are insects and feed on the Fungi: powdery mildew on rose. cells an
plants, but we do not call them disease. Only microbes Biotroph: Lives on living plant cells. Uses specialized feeding nutrients
are disease. structures, haustoria. released.
dead tiss
• There are also plants that cause problems to other plants: Disease cycle of powdery mildew of roses:
parasitic plants. Mistletoe invaginates the stem of Vegetative reproduction cycle: Conidiophore produces conidia. Conidium
When the spores land on a leaf they form a new mycelium. They Goes in
another tree and grows on the food provided by the other through
tree. penetrate the epidermal cell, and they form a haustoria, the
fungus extracts nutrients from that cell and grows. Then it goes It grows
• Orobanche: Strigolactones are hormones released by to the next epidermal cell and forms an infection area. Then you lives off
can see white mycelium. Does no meiosis whatsoever. causes r
roots to attract mycorrhizas. But here the striga takes
because
advantage of the strigolactones, when it encounters the Generative reproduction cycle: On winter, though, the fungus
Infected
strigolactones it will know it is close to the plant it can does this through a sexual way. When ascogonium and
antheridium interact, they form sexual spores that we call they form
parasitize. So, it grows on the roots of the plant without cleistothecium. They can survive in winter and in all seasons. cycle can
having to do photosynthesis. liberated ascopores spores land on a leaf (…)
,Lecture 1 Viruses, tobacco mosaic virus - What tools do the pathog
progress on the plant?
Viruses were first discovered in plants.
• There can also be a sexual cycle, sclerotium that is Bacteria starts to swim to
strong in nature can survive and start a new cycle stomata, then it enters the lea
in the next season. disease cycle is very similar in humans and plants: it to colonize it. It does not d
starts with the viral particle that enters the host cell.
tissue too much, but live
• Fungi: mushrooms, that are Wood rot fungi. the replication machinery of the plant will replicate
the nucleic acids. when it is replicated it will be nutrients floating around, th
Saprophytes, live on dead tissue.
packaged into proteins again and there are many viral producing toxins and damag
• it starts with the basidiospores. the spore is carried particles inside the cell. These viral particles are the they can live on the content
to the dead wound tissue. it produces cell-wall source of a new infection. of the dead tissue --> hemi-bio
degrading enzymes, it starts to grow on the How our virus transmit it?
degraded wood tissue and produces mushrooms Flagella important for the
that form spores. they can go through the plant cell through wounds or these microbes, the bacteria
openings and enter the cell which is still alive. They get swim and stays in the same pl
• Bacteria biotroph: Finds the natural opening like a viral particle inside the cell and the whole replication
wounds and go inside and feeds off the nutrients starts. many viral particles can move from cell to cell Type III secretion system: For
and can cause disease symptoms. The diseased through plasmodesmata (openings in the cell ) viruses needle outside the bacteriu
leaves fall on the ground other plant tissue that can use plasmodesmata. they can reach the vascular can inject into plant cells c
the bacteria can spread and infect another leaf. bundle, where there is movement of water and plant such as exotoxins or effecto
sap, they enter the phloem and transport it quickly that suppress the host imm
• Agrobacterium tumefaciens (tumours): used in throughout the plant. so the pathogen can grow bett
plant biotechnology to transform plants with a when an insect sucks the vascular bundel of the plant,
gene of our interest. This bacterium is in the soil ; Appressorium: structure that i
it will suck up the virus and is a vector to infect
it is activated by chemical compounds released by the end of a germ tube
another plant
the plant and then it starts to attach to wounded the spore lands on the plant
plant cells. Injects the T-DNA onto the plant. This VIRULENCE FACTORS:
it germinates and the ap
T-DNA resides on a plasmid . This T-DNA encodes Saprophytes do not have pathogenicity genes. forms and it can form a hug
for plant hormones and as a result , the infected with that it can penetrate the
Pathogens can obtain nutrients from living plant
tissue multiplies and leads to a tumour. The tissue, virulence genes (allow them to enter the plant) invaginate the germ tube to go
bacteria is provided with nutrients in the tumour.
Cause a crown galls, within the gall there are many - Infection and colonization: Pathogens use different
of this bacteria. If they are released into the soil, ways of entering the plant: viruses and bacteria
they can infect a new plant. Viruses can enter the plant through insects.
Bacteria can enter through stoma, wounds, etc.
, Cutinase : enzyme produced by fungi that try to Biotrophs do not d
Lecture 1 –
penetrate the plant it kills the cell, and
cuticle - cutin is the first defense layer grow anymore. For
of the plant leaf. many pathogens cell-wall degrading
form cutinase, they release cutin to be produced in a
monomers from the leaf surface of maybe they can ge
layer.
the plant and when this concentration
of cutin monomers increases these Biotrophic pathog
can be recognized by the fungal careful! Make us
pathogen and when it senses higher structures (hausto
concentration of the cutinase nutrients from plan
monomers , the cutinase genes is Haustorium: The sp
expressed to higher levels and appresorium
plant cell and ke
==> enhanced production of cutinase intact/ alive and fo
cutinase production is a VF structure the haust
• Appressoria stick to the leaf and make a small hole in the Because if fungi are mutated to The feeding struct
plant. Important for biotrophes because the cell wall is produce less cutinase they are less to take nutrients f
penetrated without killing it immediately. viral cell to feed the pa
• Attachment to surfaces- extracellular polysaccharides: allow can grow and exp
the pathogen to glue itself to the surface of a plant so that it Cell wall degrading enzymes: further. Exchange o
can attach to the plant cell surface. Many bacteria produces first layer of defense, cell wall
extracellular polysaccharides, which allow the bacteria to Haustoria or
form biofilm that is attached to the plant cell inside the plant. structures have ev
layers of cellulose, pectin, which are very difficult times and are pa
• Produce extracellular hydrophobin proteins required for to break down , except with an appressorium. lifestyles
adhesion and penetration. although cell-wall degrading enzymes such as
cellulase and pectinase , many fungi and bacteria Not all plant patho
• Physical recognition of surfaces: Some bacteria are very oomycetes make a
clever because they can recognize the surface of a host. Some can produce this once it is degraded it allows entry haustoria, many
fungi recognize the shape of stomata and use them to of the pathogen. without these struc
position infection structures (appressoria). Necrotrophic pathogens commonly produce cell
wall degrading enzymes. kill the host cell
vaccination
• Pasteur’s cholera vaccine: Pasteur isolated the bacteria from
sick chickens and grew it in the lab. One of his lab assistants
forgot to inject the chickens with a fresh batch of the bacteria
• Fusarium oxysporum causes wilt on banana. before going on vacation. They used old aged bacterial
• Wheat head blight mycotoxins are produced (deadly). Different culture on healthy chickens Chickens didn’t die like usual.
species of Fusarium cause different things. When they were injected with fresh bacteria, they still didn’t
• Sustainable crop disease strategies get sick.
• Stacking R-genes (resistance genes) from wild relatives (enable • Weakened, attenuated bacteria made the chickens immune
ETI): R-genes recognize specific pathogen effectors and trigger to disease.
a strong immune response called Effector-Triggered Immunity • herd immunity = some threshold of the population should be
(ETI). Stacking means introducing multiple R-genes into a single vaccinated so the virus does not spread.
crop to make it harder for the pathogen to evade recognition. • HIV jumps from one species to the other
Wild plant relatives often have diverse R-genes that are not • Problems with HIV vaccine: 1. safety
present in cultivated crops.
• you do not want to vaccinate with attenuated HIV particle,
• Deletion of a susceptibility (S-) gene (prevent ETS): S-genes because HIV can mutate very fast --> what if they get infected
actually help the pathogen during infection. Effector-Triggered with HIV?
susceptibility occurs when effectors supress the plant’s
immunity using S-genes. Knocking out S-genes means the • HIV mutates very fast; will the person be protected against
pathogen can’t manipulate the plant as easily. these?
• Increased ROS-production and HR (strengthen direct defense • Challenges in COVID-19 vaccination: problem is not solved
mechanisms): Plants produce ROS to kill or limit the spread of • in some individuals the vaccination causes antibody
pathogens. Hypersensitive response is a form of programmed enhanced disease. Explosion of the immune response.
cell death around the infection site – a way of isolating the Increased inflammation.
invader. We can boost this up. • Immune therapy in cancer tries to reactivate cells that can
• RNAi (gene silencing in the pathogen) specifically kill cancer cells. Specific.
• Diseases on animals affect us We have less food
• Plants release energy into the soil, to feed and select microbes
around the roots. What are the benefits? These microbes can • Zoonosis: a new virus in the wildlife populations is a potential
increase stress resilience or nutrient uptake. new virus in the human populations.
, Hemi-biotroph: Lives on living
Lecture 1 – uses specialized structures (hau
has a necrotrophic phase (feed
from killed cells). When the dise
• Healthy plant: it forms a necrotrophic phase
• Sick plant: Leaf blight, leaf discoloration, predation, Oomycetes: Oomycetes produces sp
leaf spots, wilting, abnormal outgrowth, root rot, cysts produce spores. The spores are
and root knots Sporangium is formed it can germina
leaf, but it can also form inside zoospo
• Biotic plant disease: fungi, bacteria, viruses, spores with flagella, they can swim in
nematodes. the leaves. when that happens hau
and the pathogen can progress into t
• Abiotic plant disease: draught, flooding, heat/ cold, the deeper layer of the leaf tiss
nutrition, pollution biotrophic phase and then the necrotr
• Many kind of organisms cause plant disease.
Nematodes can penetrate the worm cells and inject Pests and diseases cause major crop losses. The oom
sexual life
their needle into the plant cell, causing disease. Biotic plant disease:
Necrotro
• Pests on plants. They are insects and feed on the Fungi: powdery mildew on rose. cells an
plants, but we do not call them disease. Only microbes Biotroph: Lives on living plant cells. Uses specialized feeding nutrients
are disease. structures, haustoria. released.
dead tiss
• There are also plants that cause problems to other plants: Disease cycle of powdery mildew of roses:
parasitic plants. Mistletoe invaginates the stem of Vegetative reproduction cycle: Conidiophore produces conidia. Conidium
When the spores land on a leaf they form a new mycelium. They Goes in
another tree and grows on the food provided by the other through
tree. penetrate the epidermal cell, and they form a haustoria, the
fungus extracts nutrients from that cell and grows. Then it goes It grows
• Orobanche: Strigolactones are hormones released by to the next epidermal cell and forms an infection area. Then you lives off
can see white mycelium. Does no meiosis whatsoever. causes r
roots to attract mycorrhizas. But here the striga takes
because
advantage of the strigolactones, when it encounters the Generative reproduction cycle: On winter, though, the fungus
Infected
strigolactones it will know it is close to the plant it can does this through a sexual way. When ascogonium and
antheridium interact, they form sexual spores that we call they form
parasitize. So, it grows on the roots of the plant without cleistothecium. They can survive in winter and in all seasons. cycle can
having to do photosynthesis. liberated ascopores spores land on a leaf (…)
,Lecture 1 Viruses, tobacco mosaic virus - What tools do the pathog
progress on the plant?
Viruses were first discovered in plants.
• There can also be a sexual cycle, sclerotium that is Bacteria starts to swim to
strong in nature can survive and start a new cycle stomata, then it enters the lea
in the next season. disease cycle is very similar in humans and plants: it to colonize it. It does not d
starts with the viral particle that enters the host cell.
tissue too much, but live
• Fungi: mushrooms, that are Wood rot fungi. the replication machinery of the plant will replicate
the nucleic acids. when it is replicated it will be nutrients floating around, th
Saprophytes, live on dead tissue.
packaged into proteins again and there are many viral producing toxins and damag
• it starts with the basidiospores. the spore is carried particles inside the cell. These viral particles are the they can live on the content
to the dead wound tissue. it produces cell-wall source of a new infection. of the dead tissue --> hemi-bio
degrading enzymes, it starts to grow on the How our virus transmit it?
degraded wood tissue and produces mushrooms Flagella important for the
that form spores. they can go through the plant cell through wounds or these microbes, the bacteria
openings and enter the cell which is still alive. They get swim and stays in the same pl
• Bacteria biotroph: Finds the natural opening like a viral particle inside the cell and the whole replication
wounds and go inside and feeds off the nutrients starts. many viral particles can move from cell to cell Type III secretion system: For
and can cause disease symptoms. The diseased through plasmodesmata (openings in the cell ) viruses needle outside the bacteriu
leaves fall on the ground other plant tissue that can use plasmodesmata. they can reach the vascular can inject into plant cells c
the bacteria can spread and infect another leaf. bundle, where there is movement of water and plant such as exotoxins or effecto
sap, they enter the phloem and transport it quickly that suppress the host imm
• Agrobacterium tumefaciens (tumours): used in throughout the plant. so the pathogen can grow bett
plant biotechnology to transform plants with a when an insect sucks the vascular bundel of the plant,
gene of our interest. This bacterium is in the soil ; Appressorium: structure that i
it will suck up the virus and is a vector to infect
it is activated by chemical compounds released by the end of a germ tube
another plant
the plant and then it starts to attach to wounded the spore lands on the plant
plant cells. Injects the T-DNA onto the plant. This VIRULENCE FACTORS:
it germinates and the ap
T-DNA resides on a plasmid . This T-DNA encodes Saprophytes do not have pathogenicity genes. forms and it can form a hug
for plant hormones and as a result , the infected with that it can penetrate the
Pathogens can obtain nutrients from living plant
tissue multiplies and leads to a tumour. The tissue, virulence genes (allow them to enter the plant) invaginate the germ tube to go
bacteria is provided with nutrients in the tumour.
Cause a crown galls, within the gall there are many - Infection and colonization: Pathogens use different
of this bacteria. If they are released into the soil, ways of entering the plant: viruses and bacteria
they can infect a new plant. Viruses can enter the plant through insects.
Bacteria can enter through stoma, wounds, etc.
, Cutinase : enzyme produced by fungi that try to Biotrophs do not d
Lecture 1 –
penetrate the plant it kills the cell, and
cuticle - cutin is the first defense layer grow anymore. For
of the plant leaf. many pathogens cell-wall degrading
form cutinase, they release cutin to be produced in a
monomers from the leaf surface of maybe they can ge
layer.
the plant and when this concentration
of cutin monomers increases these Biotrophic pathog
can be recognized by the fungal careful! Make us
pathogen and when it senses higher structures (hausto
concentration of the cutinase nutrients from plan
monomers , the cutinase genes is Haustorium: The sp
expressed to higher levels and appresorium
plant cell and ke
==> enhanced production of cutinase intact/ alive and fo
cutinase production is a VF structure the haust
• Appressoria stick to the leaf and make a small hole in the Because if fungi are mutated to The feeding struct
plant. Important for biotrophes because the cell wall is produce less cutinase they are less to take nutrients f
penetrated without killing it immediately. viral cell to feed the pa
• Attachment to surfaces- extracellular polysaccharides: allow can grow and exp
the pathogen to glue itself to the surface of a plant so that it Cell wall degrading enzymes: further. Exchange o
can attach to the plant cell surface. Many bacteria produces first layer of defense, cell wall
extracellular polysaccharides, which allow the bacteria to Haustoria or
form biofilm that is attached to the plant cell inside the plant. structures have ev
layers of cellulose, pectin, which are very difficult times and are pa
• Produce extracellular hydrophobin proteins required for to break down , except with an appressorium. lifestyles
adhesion and penetration. although cell-wall degrading enzymes such as
cellulase and pectinase , many fungi and bacteria Not all plant patho
• Physical recognition of surfaces: Some bacteria are very oomycetes make a
clever because they can recognize the surface of a host. Some can produce this once it is degraded it allows entry haustoria, many
fungi recognize the shape of stomata and use them to of the pathogen. without these struc
position infection structures (appressoria). Necrotrophic pathogens commonly produce cell
wall degrading enzymes. kill the host cell
