Adhesins -- do they play a role in the Epichloë festucae association with perennial rye grass? : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Genetics at Massey University, Palmerston North, New Zealand
Loading...
Date
2014
DOI
Open Access Location
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Massey University
Rights
The Author
Abstract
Adhesins
have
been
extensively
studied
and
characterised
in
prokaryotes
and
yeast.
It
has
been
shown
that
these
proteins
are
important
in
development,
symbiosis
and
pathogenicity.
However,
less
is
known
about
the
role
adhesins
play
in
filamentous
fungi.
Adhesin
genes
have
been
identified
and
functionally
characterised
in
Metarhizium
robertsii
and
recently
studied
in
Beauveria
bassiana.
The
insect
pathogen
M.
robertsii
has
two
adhesin
genes,
Mad1
and
Mad2,
which
were
shown
to
be
important
in
insect
adherence
or
plant
adherence
respectively.
Epichloë
festucae
has
two
adhesins,
adsA
and
adsB,
homologous
to
Mad1
and
Mad2
respectively.
Bioinfomatic
analysis
of
E.
festucae
adhesins
showed
that
in
Fl1
adsA
and
adsB
are
separated
by
25
genes.
Analysis
of
adsB
illustrated
that
the
second
adhesin
gene
is
restricted
to
the
Hypocreomycetidae.
Phylogenetic
analysis
confirmed
that
adsB
and
adsA
group
separately
in
filamentous
fungi.
In
this
study,
deletion
mutants
of
E.
festucae
adsA
and
adsB
were
used
to
determine
if
one
or
both
adhesins
played
a
role
in
establishment
of
the
hyphal
network
in
culture
and
in
symbiotic
association
with
L.
perenne.
Deletion
of
adsA
did
not
alter
the
growth
of
the
hyphae
in
culture
or
in
planta.
Although,
the
growth
of
the
adsB
mutant
in
culture
was
not
affected
the
growth
in
planta
was
different
to
that
seen
in
wild--type
associations.
Mild
whole
plant
stunting
and
colonisation
of
the
large
vascular
bundles
indicates
that
adsB
plays
a
role
in
the
early
development
of
the
symbiotic
association.
In
contrast
to
M.
robertsii
where
only
Mad2
confers
adherence
of
yeast
to
onion
epidermal
tissue,
both
E.
festucae
adsA
and
adsB
confer
adherence.
The
attachment
of
yeast
cells
expressing
adsA,
suggests
that
adsA
does
play
a
role
in
the
symbiotic
association.
Physical
attachment
of
the
hyphae
to
host
cells
was
not
abolished
when
either
adsA
or
adsB
were
deleted
in
E.
festucae,
suggesting
gene
redundancy
in
regards
to
physical
attachment
to
the
host
tissue.
This
work
provides
insight
into
the
role
adhesins
play
in
the
symbiotic
association
of
E.
festucae
and
L.
perenne.
Description
Keywords
Epichloë festucae, Genetics, Lolium perenne, Cell adhesion molecules, Research Subject Categories::NATURAL SCIENCES::Biology::Cell and molecular biology::Genetics