How fungi recognize and infect plants Mennat El Ghalid
“Will the blight end the chestnut?
The farmers rather guess not.
It keeps smouldering at the roots
And sending up new shoots
Till another parasite
Shall come to end the blight.”
At the beginning of the 20th century,
the eastern American chestnut population,
counting nearly four billion trees,
was completely decimated
by a fungal infection.
Fungi are the most destructive
pathogens of plants,
including crops of major
economic importance.
Can you imagine that today,
crop losses associated
with fungal infection
are estimated at billions of dollars
per year, worldwide?
That represents enough food calories
to feed half a billion people.
And this leads to severe repercussions,
including episodes of famine
in developing countries,
large reduction of income
for farmers and distributors,
high prices for consumers
and risk of exposure to mycotoxin,
poison produced by fungi.
The problems that we face
is that the current method
used to prevent and treat
those dreadful diseases,
such as genetic control,
exploiting natural sources of resistance,
crop rotation or seed
treatment, among others,
are still limited or ephemeral.
They have to be constantly renewed.
Therefore, we urgently need
to develop more efficient strategies
and for this, research is required
to identify biological mechanisms
that can be targeted
by novel antifungal treatments.
One feature of fungi
is that they cannot move
and only grow by extension
to form a sophisticated network,
the mycelium.
In 1884, Anton de Bary,
the father of plant pathology,
was the first to presume
that fungi are guided by signals
sent out from the host plant,
meaning a plant upon which
it can lodge and subsist,
so signals act as a lighthouse
for fungi to locate, grow toward, reach
and finally invade and colonize a plant.
He knew that the identification
of such signals
would unlock a great knowledge
that then serves to elaborate strategy
to block the interaction
between the fungus and the plant.
However, the lack of an appropriate
method at that moment
prevented him from identifying
this mechanism at the molecular level.
Using purification and mutational
genomic approaches,
as well as a technique
allowing the measurement
of directed hyphal growth,
today I’m glad to tell you
that after 130 years,
my former team and I
could finally identify such plant signals
by studying the interaction
between a pathogenic fungus
called Fusarium oxysporum
and one of its host plants,
the tomato plant.
As well, we could characterize
the fungal receptor
receiving those signals
and part of the underlying reaction
occurring within the fungus
and leading to its direct growth
toward the plant.
(Applause)
Thank you.
(Applause)
The understanding
of such molecular processes
offers a panel of potential molecules
that can be used to create
novel antifungal treatments.
And those treatments would disrupt
the interaction between
the fungus and the plant
either by blocking the plant signal
or the fungal reception system
which receives those signals.
Fungal infections have devastated
agriculture crops.
Moreover, we are now in an era
where the demand of crop production
is increasing significantly.
And this is due to population growth,
economic development,
climate change and demand for bio fuels.
Our understanding
of the molecular mechanism
of interaction between
a fungus and its host plant,
such as the tomato plant,
potentially represents a major step
towards developing more efficient strategy
to combat plant fungal diseases
and therefore solving of problems
that affect people’s lives,
food security and economic growth.
Thank you.
(Applause)