AY-­‐WB phytoplasma manipulations of host and non-­‐host leafhopper interactions

Kingdom, Heather (2012) AY-­‐WB phytoplasma manipulations of host and non-­‐host leafhopper interactions. Doctoral thesis, University of East Anglia.

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Abstract

Hempitera.
In
plant
hosts,
phytoplasmas
induce
physiological
changes
and
in
both
hosts
modulate
plant-­‐insect
interactions.
Previously,
interactions
have
been
examined
with
both
hosts
infected
with
phytoplasmas.
Thus,
it
is
unclear
which
organism
the
effect
stems
from
or
how
phytoplasmas
facilitate
changes.
To
investigate
phytoplasma
manipulations
of
insect-­‐plant
interactions,
the
model
Arabidopsis
thaliana
was
used
together
with
the
fully
sequenced
Aster
Yellows
phytoplasma
strain
Witches’
Broom
(AY-­‐WB)
and
vector
leafhopper
Macrosteles
quadrilineatus.
I
demonstrate
possibility
to
differentiate
effects
of
phytoplasma
infection
within
plant
and
within
insect
hosts.
To
assess
root
cause
of
changes,
AY-­‐WB
secreted
effector
proteins
were
examined,
their
roles
within
plants,
and
in
manipulations
of
vector
fecundity.
One
of
the
56
secreted
AY-­‐WB
proteins
(SAPs)
identified,
SAP11,
carries
a
nuclear
localization
signal
and
accumulates
in
plant
cell
nuclei
(Bai
et
al.
2009).
SAP11
is
shown
to
reduce
production
of
plant
defense
hormone
jasmonic
acid
(Sugio
et
al.
2011).
Stable
expression
of
SAP11
and
3
other
SAPs
in
Arabidopsis
increase
fecundity
of
M.
quadrilineatus.
In
addition,
phytoplasmas
are
known
to
affect
non-­‐host
insect-­‐plant
interactions.
Using
the
same
approach,
I
demonstrate
D.
maidis
survives
and
produces
nymphs
only
on
AY-­‐WB-­‐infected
Arabidopsis.
Furthermore,
I
show
that
whilst
SAP11
has
no
effect
on
D.
maidis
survival,
3
other
SAPs
increase
D.
maidis
survival
and
oviposition.
These
data
suggest
phytoplasmas
utilize
a
suite
of
effector
proteins
to
manipulate
both
host
and
non-­‐host
insect-­‐plant
interactions.
Thus,
AY-­‐
WB
effector
functions
extend
beyond
direct
interaction
with
plant
hosts;
they
stimulate
generation
of
insect
vectors,
and
increase
chance
of
uptake
by
novel
insect
hosts.
This
project
highlights
the
value
of
using
a
model
system
in
studying
phytoplasma
manipulation
of
their
hosts
and
gives
insight
into
development
of
evolutionary
associations
between
phytoplasmas
and
vectors.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Mia Reeves
Date Deposited: 17 Dec 2012 16:25
Last Modified: 17 Dec 2012 16:25
URI: https://ueaeprints.uea.ac.uk/id/eprint/40581
DOI:

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