The role of JAZ proteins in plant defence and hormone crosstalk.
Eleftheriadou, Garoufalia
Date: 23 March 2012
Thesis or dissertation
Publisher
University of Exeter
Degree Title
MbyRes in Biolosciences
Abstract
Phytohormones
have
a
crucial
role
in
plant
defence
responses.
The
role
of
each
specific
phytohormone
is
contingent
on
whether
the
pathogen
is
a
bio-‐
or
a
necrotroph.
In
the
case
of
the
...
Phytohormones
have
a
crucial
role
in
plant
defence
responses.
The
role
of
each
specific
phytohormone
is
contingent
on
whether
the
pathogen
is
a
bio-‐
or
a
necrotroph.
In
the
case
of
the
hemibiotrophic
Pseudomonas
syringae
pv
tomato
(DC3000)
and
the
model
plant
Arabidopsis
thaliana,
the
interaction
of
the
three
key
plant
hormones,
salicylic
acid
(SA),
jasmonic
acid
(JA)
and
abscisic
acid
(ABA),
ultimately
dictates
the
outcome
of
the
infection.
Post-‐invasion
defence
responses,
chiefly
regulated
by
the
SA
dependent
pathway
are
compromised
by
the
antagonistic
action
of
JA
and
ABA.
It
is
this
he
complex
crosstalk
between
the
hormone
pathways
that
propels
susceptibility
or
resistance.
The
Jasmonate
ZIM
domain
(JAZ)
transcription
repressors
are
crucial
part
of
the
JA
signaling
cascade.
JAZs
form
a
co-‐receptor
with
F-‐BOX
Coronatine
Insensitive
(COI)
1
that
binds
the
bioactive
form
of
JA,
Jasmonic
Isoleucine
(JA-‐Ile).
Subsequent
to
this
JA
perception
is
the
specific
degradation
of
JAZ
proteins
that
allows
transcription
of
early
JA-‐related
genes.
Interestingly
the
bacterial
phytotoxin
coronatine,
which
is
a
JA-‐Ile
mimic,
increases
bacterial
virulence
by
exploiting
the
JA
signaling
pathway.
In
this
project
we
establish
the
DC3000
induced
susceptibility
of
jaz10
and
jaz5/10
loss
of
function
mutants
that
substantiates
JAZ
specificity
and
confirms
coronatine-‐induced
virulence.
In
addition,
we
demonstrate
the
different
manifestation
of
symptom
development
caused
by
absence
of
key
positive
regulators
of
plant
defence,
SA
and
JAZ5/JAZ10
and
uncover
the
severely
compromised
phenotype
of
jaz5/jaz10/aao3/sid2-1.
Finally
we
produce
the
tools
that
will
allow
further
research
of
JAZ
protein
interactions.
MbyRes Dissertations
Doctoral College
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