Understanding of plant colonization
by endophytic bacteria by tracking them inside
plants
Dr. Stéphane Compant
Bioresources Unit, Health & Environment Department,
AIT Austrian Institute of Technology GmbH,
3430 Tulln, Austria
[email protected]
Introduction
Bryophytae,
Pteridophytae,
Gymnospermae
Angiospermae
Contain various
bacterial taxa
Adv. Agronomy in press
Endophytes in various plants
Introduction
Various bacterial taxa
analyzed, communities
described by cultivable
/metagenomic analysis
But what can be
their niches and
ways of
colonization?
Adv. Agronomy in press
AEM 2005a SBB 2010
Endophytes analyzed in different organs such as roots,
stems, leaves, flowers and fruits and seeds of many plants
Firmicutes
Endorhiza
Rhizoplane
Introduction
Co
Rh
Native microflora in the
rhizosphere and endorhiza
c
Xy
Xy
a
b
d
Co
Rh
acillus spp.
f
h
Co
e
g
i
Rhizosphere colonization and endophytism by bacteria
Example with
Bacillus spp. in
grapevine
Introduction
Native microflora in stem
Endophytism in xylem vessels by bacteria
Introduction
Native microflora in flowers
Example with
flowers of
grapevine
Microbial Ecol 2011
Presence in various tissues of flowers
Introduction
Native microflora in fruits and seeds
Microbial Ecol 2011
Presence in fruits and seeds
General ways of colonization by endophytes
Sbb 2010
From the soil then to the other plant parts
General ways of colonization by endophytes
There is some microbes inside
plants, they derive from the soil,
and colonization should be studied
1887
MLV Galippe
“The 125th anniversary of the first postulation
of the soil origin of endophytic bacteria – a tribute to MLV Galippe”. Plant and Soil 2012
Other ways of colonization by endophytes
Endophytes can also derive from
•
•
the caulosphere,
•
the laimosphere,
•
the anthosphere,
•
the phyllosphere,
and the carposphere
SBB 2010
Other sources of colonization
PGPB effects and endophytic bacteria: niches should be
determined
Endophytes once
applied
Angiospermae
where can be present the beneficial bacterium once applied?
Under greenhouse or field conditions
?
Stem and
leaves, flowers,
fruits
Roots
Should be
determined
before to study
ISR
?
AEM 2005; SBB 2010
Which tissues? Which organs are colonized? Does the bacterium
interact with the native plant microbiome? Persistence?
Tools to track microbial colonization
Various tools to study the colonization
process and behaviour of beneficial bacteria
Microscopic tools:
Intercaling DNA markers, peptide and lipid
markers
gfp/DsRed/gusA markers,
FISH, DOPE-FISH, LNA-FISH, PNA-FISH,
card-FISH etc
It depends of the model used and if field
experiments are used or not
In order to track the microbes once applied. To know their
sites of colonization
Colonization behaviour of B. phytofirmans strain PsJN
100
µm
Soil Biology and
Biochemistry 2010
30
µm
30
µm
30
µm
75
µm
100
µm
PsJN::gfp2x on the rhizoplane of grapevine.
FEMS Microbiol Ecol 2008
Colonization from the soil
Colonization behaviour of B. phytofirmans strain PsJN
Secondary root
Exodermis
Rhizodermis
Rh
Exodermis
Exodermis
Ex
Endodermis
Cortex
Co
Xylem
Co
Cortex
En
Root hair Hairy root
Endodermis
Central
cylinder
Pericycle
Cc
a
b
c
Xy
d
ficial endophytic bacteria.
Soil Biology and
Biochemistry 2010
r epi- and endophytic microorganisms.
PsJN::gfp2x inside endorhiza of grapevine.
Fems Microbiol Ecol 2008
Colonization from the soil
Colonization behaviour of B. phytofirmans strain PsJN
Berry
Pedicel
10 µm
a
Vegetative and
reproductive organs
10 µm
10 µm
Xylem of stalk
Inflorescence stalk
a
b
b
Fems Microbiol Ecol 2008
Colonization from the soil and then a spread to reproductive organs
Colonization of grapevine by NRRL B-24137
PGPB
Saccharothrix
algeriensis NRRL
B-24137
Colonization?
DOPE-FISH
microscopy of S.
algeriensis NRRL B24137 10dpi
Soil Biology and
Biochemistry 2010
Plant and Soil 2013
colonization from the rhizosphere to rhizoplane at root hair level
and secondary root emergence site
Colonization of grapevine by NRRL B-24137
DOPE-FISH microscopy of S. algeriensis NRRL B-24137 10dpi
PGPB
Saccharothrix
algeriensis NRRL
B-24137
Colonization?
Soil Biology and
Biochemistry 2010
Plant and Soil 2013
colonization from the rhizosphere to rhizoplane at root elongation
zone
Colonization of grapevine by NRRL B-24137
DOPE-FISH microscopy of S. algeriensis NRRL B-24137 10dpi
Secondary root
Rhizodermis
Exodermis
Exodermis
Cortex
Root hair Hairy root
Endodermis
Central
cylinder
Pericycle
eficial endophytic bacteria.
er epi- and endophytic microorganisms.
Soil Biology and
Biochemistry 2010
colonization of the endorhiza of grapevine plants
Plant and Soil 2013
Wheat colonization of a beneficial bacterium from
desert soil by using other tools
Collaboration with A. Zitouni and O.
Toumatia IBSM alger, Algeria
A biocontrol Streptomyces mutabilis strain, isolated from desert soil,
applied on wheat. It reduces Fusarium spp. contamination on roots,
but where can be the microbe once inoculated?
Wheat colonization behaviour of a Streptomyces
mutabilis strain in wheat
DOPE-FISH Microscopy using HGC69a probe coupled with dylight 594
Streptomyces sp. appeared
as orange colored and
different forms.
My: mycelium, Pmy: pack of
mycelium. Al: aleuronic cells,
En: endocarp, Endos:
endosperm,
Enp: endopleura, Ep:
epicarp, Me: mesocarp,
In preparation
Sites of colonization inside the fruit parts of the caryopsis,
e.g. up to the endocarp
Colonization behaviour of a Streptomyces
mutabilis strain in wheat
DOPE-FISH Microscopy using HGC69a probe coupled with dylight 594
Streptomyces sp. appeared as orange colored. Gsp: germinated spore, My:
mycelium. Ep: epidermis, Pa: parenchyma, Xy: xylem
In preparation
Better colonization inside leaves. From the phyllosphere to
internal tissues but also spread inside xylem vessels
General ways of colonization by endophytes
Sbb 2010
From the soil then to the other plant parts but it depends of
the strain!
Conclusions
Different tools and process of
colonization
•
•
•
Knowledge on microhabitats of
applied
strains
and
natural
microflora
Allow to determine if the strain, once
applied, can colonize plants and
various organs or be restricted
Biofertilization
and
biocontrol
properties and studies will depend of
these colonizations
but if you use a strain in the field how to differenciate it from
the native plant microbiome if the species already exist?
Microbes can restrict their studies of colonization
Bioresources Unit, Tulln, Austria
A. Sessitsch
Head; Senior scientist
• Deciphering the plant
microbiome
• Genetic/omic analysis of
beneficial strains
• Mechanisms of plantmicrobe interactions
• Biocontrol
of
plant
diseases
• Biofertilization of crops
• Biomiming
G. Brader
F. Trognitz
B. Mitter
E. Hackl
S. Compant
Project leaders-Scientists working on plant-microbe interactions
Vielen Dank