This content explores the scientific challenges of plant pathogens, particularly oomycetes like Phytophthora, and introduces an innovative approach to communicate this complex research through the art of ballet.
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Well, thank you everybody for coming and
thank you for that lovely introduction,
Miffi. Uh, so I mean what a title,
right? Uh, so let's start by trying to
break down this massive title which puts
together so many different things. So
plant pathogens and pirouetses. So you
know plants, what are plants? I think
we're all pretty much familiar with
plants. So, we've all seen, you know, green
green
um beings around us all the time, but
let's look at what a plant is from uh a
sort of more precise scientific point of
view. So, this is a tree of life. So,
representation of how kingdoms of life
are divided and how they are related to
each other. And you can see here uh we
have a time axis which shows us over
time what evolved earlier and later and
how we started from Luca which is the
last universal common ancestor. So the
very first living cell and the tree then
splits into bacteria and archa which are
single cellled organisms and then we
have the evolution of multisellular
organisms and we have animals plants and
fungi and plants are all the way up
there. Now to give you an idea of how
animal cells are different from plant
cells let's look at some basics. So in
general quite similar they all are
ukarotic. So they have nuclei where DNA
is contained here and there. But one of
the main uh striking characteristics of
plant cells is the cell wall. So this is
a structure that is outside the cell
membrane. So animal cells have cell
membranes. We plant cells also have cell
membranes. But a cell wall is a rigid
structure which essentially keeps the
structure of the cell contained and
that's why plants are still static. Uh
the other thing that is present in both
but not quite the same is the vacule. So
the vacule is present in animal cells
but it is usually small. It's a membranebound
membranebound
um organel that contains liquid and it
is quite variable in its size and how
many there are in animal cells. In plant
cells, there's always a very very large
vacule and it takes up a lot and in some
cases most of the cell size and it
maintains with tur pressure, it keeps
that cell membrane attached to that cell
wall. So it maintains its shape and you
know the elephant in the room is the
chloroplast. The chloroplast is an
organel just like mitochondria are. And
while plants also have mitochondria. So
here we are have some mitochondria here
and also here plants have chloroplasts
which is what allows them to get their
energy from the sun and do
photosynthesis and it has evolved later
on. So plant cells have evolved later
compared to animal cells.
Now let's talk about pathogens. So
pathogens are not a specific group. They
are several types of organisms. So we're
thinking bacteria
for example or uh insects, viruses,
uh filamentous organisms or nematodes.
So nematodes look a bit like worms but
they're not quite worms. Uh which
essentially make in this case a plant
ill. That's what a pathogen is. Very straightforward.
straightforward.
Now, why do we care about plant
pathogens? That is, you know, we all
know why we care about human pathogens.
We all get sick and we really want to
feel better. Well,
we lose about 40% of agricultural yield
annually to plant pathogens and to plant disease.
disease.
And there aren't many ways that we know
how to treat these or how to stop these.
And this is currently an extremely big
problem because people's livelihoods
depend on this and also how much
um how much food the growing population
has. So this is a really big problem. We
can treat all the diseases we want but
if we don't have anything to eat we will
die. It's not much way around that. So I
particularly am interested in
filamentous pathogens. So filamentous
pathogens are these in uh within the
sort of what we're looking at and there
are really two types of filamentous
pathogens. Fungi and omy.
So let's start by looking at fungi. So
fungi are up here um in that tree of
life. So they are multisellular. They're
actually more closely related to animals
than they are to plants. And this might
be striking for a lot of people which
often think that they are actually
similar to plants, but they really
aren't. They don't have chloroplasts.
They cannot photosynthesize.
Now, we all kind of know what a fungus
is. But spoiler alert, uh a mushroom is
not a fungus. A mushroom is part of a
fungus, is an organ of a fungus. The
same way
a gut is a human organ.
All of that is also part of the fungus.
And that part is called a mycelium.
Now here you see a more detailed picture
of a mcelium. So these parts up here
that you see are mushrooms. And all this
sort of thread like structure is a mycelia.
Now if we look at a sort of a schematic
of a fungus. So the whole thing is a
fungus. And it's very easy looking at
the schematic to assume that this is a
bit like a tree. So you have the mcelium
that are the roots and that the mushroom
that is a tree. But that is actually not
the case. This is a lot more
uh representative of what it is. So this
is the mcelium is the main part the
permanent part of the fungus. So that
lives all year round a bit like the
entire plant. And the mushroom is
actually also called the fruitting body.
So it is just the fruit and it carries
and disperses spores. So a bit like uh
um a bit like a fruit and an apple with
its seeds.
So let's look let's zoom into the
mcelium. So the mcelium is made of these
structures called hy. This is an
electron microscope image of hyi. So
these hyi are 10 microns in diameter.
That's about onetenth of the thickness
of a hair. So very very thin. And uh
they grouped together they form the
mcelium. And they are formed by single
cells cell lines. So this is a bunch of
single cells attached sort of front to
back and they each have a nucleus. Now
some types of fungi, not all species
actually are aseptidate. So they don't
have any division between cells and
there's just essentially one very large
and long cell which are bunch of nuclei
inside it.
So the whole mycelium tends to grow if
if it's not constricted by anything. It
grows in a sort of circular fashion and
it comes from a spore that germinates.
And this is what uh a mcelium looks like
in a petri dish. So this petri dish is
about that big. And that is kind of what
you tend to see uh how it grows. This
sort of oh sorry this sort of fluffiness
is the mycelium.
And this is well it's not magnified but
the picture is not magnified but of
course it's blown up. So this is what
you see with the naked eye. Now let's
move on to my seeds. So my seeds are
also filamentous
uh but they are absolutely not related
to fungi. They were originally thought
to be related to fungi but when their
DNA was sequenced we discovered that
they actually genetically are not even
close. they diverged way before
um before fungi and they are not um
related at all. Now when you look at
them in the lab or on a plate they also
have hy and they look exactly the same
but there are a few uh key differences
and one of them is their spores. So all
omi my seeds have uh these swimming
spores that have two fleella. Not all uh
fungi have um most fungi don't have
swimming spores. Some do but none have dlagulated
dlagulated
spores. So this is a key distinction.
And they do swim around in this sort of
very chaotic. This is real time. This is
not accelerated. So that's how quickly
they sort of swirl around.
And then these spores um originate from
this is essentially the fruing body
called a spiranga and it's sort of the
equivalent the microscopic equivalent of
a mushroom. And um they essentially
burst when they're in contact with
liquid and release the spores. And this
is what a spiranga looks like under the
microscope. These are detached from the
mycelia and you can see the spores
inside and one actually has germinated
and it's starting to grow a new mycelium.
mycelium.
And the other interesting thing about
omices is that almost all of them are
pathogen pathogens and most of them are
plant pathogens. Um this is a very
interesting niche as they evolved before
plants. uh but the nonetheless what it
is like and so most of them do require a
host which usually and and need the the
plant cells to be able to grow a full
mcelium and then um
repeat their life cycle. Now what uh the
pathogen the omic pathogen that I
studied most is called phytoera. This is
a genus of pathogens which has a variety
causes a variety of plant diseases and
um I looked specifically at two of
these. One is phytosterone infestance.
So I think all of us know the Irish
potato famine. Um so phytosterone
infestance is the cause of the Irish
potato famine and it causes potato late
blight. uh which essentially makes the
tuber rot like that but also the plant
essentially rot and it can also infect
tomato and this is what happens. This is
time lapse of a few days about a week of
a tomato infection and it just fully
rots and again no crop protection
strategies against this. We can not
prevent it. It doesn't respond to
fungicides because it's not a fungus.
And then the uh its awful cousin, the
tropical cousin of phytotera infestance
is phytotera pulvera which is a
generalist pathogen. So it kind of
infects pretty much anything but is
currently being a huge issue for
chocolate and cocoa. It causes black pod
disease. So this for I think a lot of us
have not seen what a cocoa tree looks
like. So these are cocoa um fruits which
contain cocoa beans and this is what
they look like once they're infected. So
they just fully rot on the inside. And
the problem is that these plantations
are also a very big investment for the
families that use them that have them
because these trees take years up to 10
years to uh grow and have a productive
plantation and then within a year uh
phytola can completely wipe out your
plantation and then contaminate that
soil for another 10 years. So that can
be a really long-term damage to
uh people's livelihood.
And again, no crop protection strategy
available. Some farmers tend to go and
sort of chop off infected parts of the
plants, but that can be only a
short-term solution. And and unless you
eradicate the presence, one spore is
enough to really destroy your field,
which is quite an urgent issue. if we
still want to have chocolate in 10 years.
years.
Now we know how the infection process
works. So once a spore attaches to uh so
this imagine is the side of a leaf um
with the cells of the leaf here. So the
spore will attach then will germinate
and will form what is called an
apressaorium. So this is uh a microscopy
image. So the uh pink uh is are the
plant cells and you can see the yellow
spores that are germinating
and then when they form a prisa uh they
essentially um use uh literal pressure.
This was measured. There were
experiments done by physicists that
measured the pressure and it can apply
such a strong pressure that it makes a
hole in the cuticle and then penetrates
and grows between the cells not within
the cells and then it forms these uh
digit-like appendages called htoria
which essentially um are feeding
appendages where it in it breaks the
barrier between the plant cell and the
um the pathogen cell and it acquires
nutrients and pumps other uh proteins
within the plant. And this is what that
looks like. You can see these pink blobs
are the nuclei corresponding to this
part of the plant. And then you can see
the digit-like appendages growing inside
the cells.
So how do plants defend themselves? Do
we know? Well, we know some. So most of
you are familiar with animal immune
system. Almost almost all animals not
all animals have an innate immune system
and an adaptive immune system. The
adaptive immune system is what vaccines
are based on and how we can generate uh
immunity in and and make a person
resistant to a disease. For example,
resistant is probably not the right word
for people. Fran will correct me later.
Uh well plants only have innate
immunity. So there is no real way to
make a plant resistant an individual
plant resistant to a pathogen. And the
innate immune system in the plant is
divided into pattern triggered immunity
andector triggered immunity. These two
uh happen at different times and are
different levels of immune response. So
pattern triggered immunity occurs before
the pathogen enters the cells and it's
based on these receptors which are
called pattern recognition receptors
um which poke outside of the cell. So
imagine this is the cell of the plant.
These poke out and they recognize pumps
which are molecules that are common to a
variety of pathogens. So um things like
kitin which is present on the outside
coat of some fungi uh but also of
insects uh these are recognized by these
receptors and then they activate a
signaling cascade which causes a more
mild immune response usually a Ross
burst which is an excretion of reactive
oxygen species which are a bit acidic
essentially and damage the pathogen.
Now they also recognize damps which are
damage associated molecular patterns. So
essentially if an insect is chewing on
the plant, the plant will recognize its
own molecules that have been chewed up
and send an alert. Oh, I'm being chewed
up. I need to react.
Now triggered immunity happens later.
That happens once we've had penetration.
Andector triggered immunity is specific.
it's specific to a species of plant and
a species of pathogen while pump uh well
um PTI is very general general response.
So for example, we could have uh wild
potato resistant to phytosterone
infestance. And how this works is that
usually pathogens evolve ways to subvert
uh pattern triggered immunity. And they
do this by pumping these molecules calledectors
calledectors
inside the cell and blocking the immune
response, the pump triggered immune
response. Butector triggered immunity
uses resistance proteins which evolve
inside the plant to recognize thesectors
and then mount a much stronger defense.
So hypers sensitive response is a very
strong way to
to prevent a pathogen spreading which is
done by killing a bit of yourself to
prevent the spreading also known as hypoptosis
hypoptosis
uh in animal terms or program cell
death. And this is what it looks like in
a plant. So this is uh a bunch of cells
that essentially have uh are um dead and
if the pathogen is inside there it will
not be able to spread. And this is what
it looks like against viruses because
viruses tend to infect a bunch of
different cells. So you will get a lot
of little uh dots.
Now what happens is that this over an
evolutionary time span uh we will get
continuous production and evolution of
new aectors from the pathogens which
subvert again this uh the plants uh the
plant's ability to respond to them and
the plant in terms will evolve
continuously new resistance protein to
prevent the pathogen from escape.
shaping its immune response. And this
leads to what is called the red queen
effect which is taken from uh Alice's
Adventures in Wonderland. So this idea
that you need to keep running and keep
evolving to stay still because you need
to keep evolving new and new proteins to
be able to maintain this equilibrium
But all of this information comes from leaves
leaves
and that is a problem. So
So
very few people study roots.
However, 90%
of those plants that are lost to
pathogens are lost to root pathogens. And
And
nobody looks at roots. There is reason why
why
roots are in soil
there. That's very hard to look at. It's
very hard to study things that are
inside this very opaque matrix. You need
to be able to somehow extract it and
look at that. And not not only that, but
there is so much going on in soil. You
have different species of plants
interacting with each other and
interacting with a variety of different
species of um beneficial and pathogenic
interactors and in different soil types
with different context.
That is a lot of complexity and
scientists like simple things. So this
is a lot to handle and
also interactors exist on a spectrum. So
they exist on a spectrum from mutualism
in which both interactors
benefit from the interaction. So this is
an example of riseobia which is a type
of bacteria that forms these root nodules
nodules
um in legumes. And these bacteria
essentially produce nitrogen, fix
nitrogen and give nitrogen to the plant
and the plant in terms uh provides um
carbon to
to the uh bacteria. So this is a very
good relationship for both of them. And
then on the other side of the spectrum
you have ptoenic interactions like the
phytotera one that I showed you before.
So we get infection from a filamentous
organism and now that's even more
complicated when you insert context and
the presence of multiple of these
organisms. So it is known that if a
positive interactor like um our bascular
microisa this is a type of u of fungus
that is actually beneficial colonizes
roots and is beneficial to these roots.
If that is present in a plant, then a
pathogen like phytoera will really
struggle to infect.
And all of this is also further
complicated by the type of soil you're
in. So different types of soils will uh
for example a more acid or a more basic
environment might affect how this
Well, let's simplify this. Do we know
how phytopherosa spores find a root? We
we sort of do. So phytosteraspores are
released from spiranga uh when water
usually irrigation water touches the
spiranga and then they swim towards the
root and they attach essentially here to
the tip of the root. when they uh are
stuck there that's when they have
attached and they do this process called
insistment and then from there they will germinate
now the question is can we actually stop
them from finding the root and this is
really what I care about and what I want
to do in life look at this so I'm going
to tell you about how I helped look into
this during my PhD which is only a
little part of the work that I hope to
Now, this is a V slide. It's um a little
contraption about that big that I built
during my PhD, and it allows me to put
things in the middle here in a liquid
and apply an electric field. Now, if we
put phytoera uh spores in there and we
apply an electric field, they all swim
to the positive pole.
And we thought, well, what if we try and
use this?
Can we prevent spores from attaching to
a root by driving them away using an
electric field?
And uh what we're really trying to do is
essentially subvert this very first part of
of
the infection process. And that's why I
built this other contraption. This is 3D
printed. And you have your little roots
here. And then you have an electric
field applied to the side.
And what you can see here is the the
spores which are yellow really do attach
and infect the root when there is no
electric field. But they don't when
there is an electric field. And we also
quantified that. And you can see that
it's quite effective.
So at this point we wanted to make sure
that this helped reduce the overall
infection and just and not just the
first part of the infection. So
essentially once if we reduce the number
of the spores that attach here do we
actually get less growth in the plant
and we quantify the plant growth sorry
not the plant growth the pathogen growth
inside the plant and the answer is yes
it does help. It actually really really helps.
helps.
Now, you probably thought I forgot, but
we're also talking about pirouettes. So,
a pirouette is a ballet step in which
the dancer turns around few times,
hopefully hopefully two, three times
around itself and um within a ballet. Um
so, probably I should now say that I am
a ballet dancer as well and I've been a
ballet dancer for a very long time. And
something that I've been asked um
repeatedly, I want to say in interviews
as well, uh is what do science and
ballet have in common?
And the answer to that for me is storytelling.
storytelling.
So science tells a story. We spend years
and years looking at all the details of
how something works and then we describe
it in a scientific paper. This is my
first first author paper for my PhD.
have quite a few now, but that was
special. Um, and ballet is another way
to tell stories, usually more of a human
story. Here we have an example of Romeo
and Juliet performed by your ballet. And
And
if ballet is so good at telling stories,
can we use it to tell a science story?
Well, that's how the Sai Ballet project
was born. So I currently run the Sai
Ballet project and we've been able well
with the help of quite a few people uh
bring three different projects into uh
ballet. So there is the crop protection
project which is my PhD project but then
we also did uh something about uh a
ballet on atmosphere uh and how global
warming and different types of particles affect
affect
um affect the way uh the atmospheric
warming is happening. And also we did uh
one on sort of a more social science and
how uh community behaviors can um can
have an effect on uh climate science overall.
overall.
Now today I'm going to tell you a bit
more about my PhD research and how I put
that into ballet. So my PhD research was
pretty much spent at the microscope and
that means I had a lot of visual
information to work with. So at the
microscope um I looked at how a plant
germinates and I tried to reproduce that
in ballet form. So this is a plant
germinating. This is a bean and it
germinates with the first radicule
which I used uh the extension of the leg
to mimic that. And then uh what emerges
from the top here are the two cotilons
which are the two embriionic leaves. And
again I used the arm movement to mimic
that uh cotilidon uh germination.
Then uh we move on to the spore, the
pathogen spore movement. And I used
these circular movements for the dancers
interpreting the pathogens to mimic the
sort of chaotic swimming behavior that
you see here. And then finally I try to
look at spore attachment by getting the
dancers to attach one at a time to the
actual plant and then grow in a sort of
Well now let me actually show you the
Heat. Heat.
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