PLANT PATHOGEN
INTERACTIONS
IN TODAYS LECTURE:
Plant disease
A few types of plant pathogens
Pseudomonas as a model for studying plantpathogen interactions
INNATE IMMUNITY
Plant's tools for preventing disease
Melotto et al., Stomata in PTI.
Julian Avila 5/20/2014
Why should we care
Liz West
THE STRATEGIES PATHOGENS USED ARE
DIVERSE
Biotrophic
Powdery mildew on
cabbage
(Oomycetes)
HOST SPECIALIZED
Phytophtora infestans
Hemitrophic
Pseudomonas syringae
Botrytis cinerea
Necrotrophic
HOST SPECIALIZED
NON-HOST SPECIALIZED
Plant pathogens in
the news
Liz West
http://www.apsnet.org/publications/imageresources/Pages/default.aspx
LIMEPOCALYPSE
Retrieved on 5/13/14
http://tech.fortune.cnn.com/2014/05/09/a-big-data-look-at-the-lime-shortage/
SAP
CITRUS GREENING DISEASE
(Huanglongbing)
Huanglongbing on mandarin oranges 黃龍病
- Insect transmitted
- Bacterial (Candidatus
liberibacter)
- Phloem restricted
- Originally found in Asia
- Appeared in Florida in
1998
- Reported in Mexico in
2009
- No treatment or
resistant variety known
PLANTS
vs.
PATHOGENS
Using what you have learned in your lifetime,
compile a list of all the strategies you can think of
that pathogens and plants have developed to cause
and prevent disease respectively.
For example
The pathogen Candidatus liberibacter enters plant
tissue in wounds caused by plant-feeding insects.
Plants release chemical compounds to warn other
plants of insect attacks.
PLANTS
vs.
COLONIZE
- ENTRY MECHANISMS
THRIVE
- REPLICATE
- DIVIDE
- REPRODUCE
PATHOGENS
CHEMICAL WEAPONS
DETECTION SYSTEMS
DECOYS
PHYSICAL BARRIERS
SABOTEURS
Pseudomonas syringae as
pathogenesis/resistance model
Bacterial Speck
Disease
Caused by Pseudomonas
syringae pathovar tomato
(Pst)
Pseudomonas syringae as a model
P. syringae pv. syringae B728a vs.
P. syringae pv. Tomato DC300
by Tom Zitter and R. Thilmony
Conveniently, Pst can also infect
Arabidopsis thaliana
PNAS 102(31): 11064–11069
Conveniently, different P. syringae
strains have been sequenced
Pst colonization mechanism
EPIPHYTIC GROWTH
INFECTION OF
SUSCEPTIBLE PLANTS
- Pst can survive on the
STOMATA
leaf surface.
- Pst enters the
apoplast through
stomata or wounds
APOPLASTIC GROWTH
Melotto et al. 2006
Colonization
A) Open (top and middle
panels) and closed stomata
(bottom panel).
Melotto et al. 2006
(B) Stomatal aperture in
intact leaves (left panel) or
epidermal peels (right panel)
of Col-0 plants exposed to
water
(white
bars)
or
Pst DC3000 (gray bars). In
this and all other figures,
results are shown as mean (n
= 60 stomata) ± SEM unless
otherwise noted.
Colonization
PLANT RESPONDS TO THIS
NON-SPECIFICALLY
2h
Melotto et al. 2006
4h
Pst DC3000
Pst USED A
WEAPON
Stomatal aperture in epidermal peels of
Col-0 plants exposed to water (white bars)
or E. coli O157:H7 (gray bars).
E. coli O157:H7
What do plants sense in pathogens?
(E) Effect of the Nitric Oxide Synthase
(NOS) inhibitor L-NNA (0.2 mM) on
stomatal closure when coincubated
with PAMPs (5 mM flg22 or 100 ng/ml
LPS)
THIS FIGRE GIVES US INFORMATION
ON:
- EXAMPLES OF WHAT PLANTS
SENSE
- A GLIMPSE INTO THE MECHANISM
BY WHICH STOMATA CLOSE IN
RESPONSE TO SENSING
PATHOGEN/MICROBIAL
ASSOCIATED MOLECULAR
PATTERNS (PAMPs/MAMPS)
•
•
•
•
•
•
•
FLAGELLIN
ELONGATION FACTOR Tu
PEPTIDOGLICAN
LIPOPOLYSACCHARIDE
CHITIN
XYLANASE
HEPTAGLUCAN (HG)
*flg22 is a short immunogenic
fragment of flagellin
FLAGELLIN
Flg22:
QRLSTGSRINSAKDDAAGLQIA
The Plant Journal (1999) 18(3), 265–276
PAMP TRIGGERED (INNATE) IMMUNITY PTI
The perception of PAMPS triggers a set of defense
responses. In the next couple of slides we will explore
some of them.
PAMP TRIGGERED (INNATE)
IMMUNITY - PTI
Pst
Pst
Transient ROS production in response to live Pst DC3000 wild type
Arabidopsis Col-0. A: Time-course of ROS production in response to Pto DC3000
(n = 48/treatment). RLU, Relative Light Units
How does this experiment
work?
WHY WOULD PLANTS PRODUCE H2O2?
REACTIVE OXYGEN
SPECIES
CHEMICAL WEAPONS
PTI
• STOMATAL CLOSURE
• REACTIVE OXYGEN SPECIES
PAMP TRIGGERED (INNATE)
IMMUNITY - PTI
MAPKs
Mitogen Activated
Protein Kinase
Myelin basic protein
(an MAPK substrate)
flg22 activates MPKs. MAPK activation with or without 100 nM flg22
for 10 min (top) and expression of each MAPK are shown (bottom).
(Tagged kinases were immunoprecipitated from lysates of transfected protoplasts with
the corresponding antibody and analysed with a known substrate as indicated.)
PROTEIN
PHOSPHORYLATION
STRUCTURE
INTERACTION PARTNERS
ACTIVITY
PROTEIN STABILITY
LOCALIZATION
One of the most ubiquitous types of post-translational modifications
MAPKs
KINASE ASSAY
MAPK9
TAG
Which MAPK is activated by flg22?
Plasmid
(32P incorporated)
Plant protoplasts
MAPK
γ-32P- ATP
MAPK
P
MBP
TAG-binding resin
The amount of incorporated
phosphate shows the
catalytic activity of the
kinase.
PAMP TRIGGERED (INNATE)
IMMUNITY - PTI
Stimulus 1
Stimuli
MAPKs
Stimulus B
P
P
60
Mitogen
Activated
Protein
Kinase
Cascade
MEK1?
MAPKKKs
P
10
MAPKKs
20
MAPKs
P
P
MAPKK4/
MAPKK5 P
MAPK3/
MAPK6
Response
RESPONSE
A
(32P incorporated)
RESPONSE
RESPONSE
B
PTI
•
•
•
•
•
STOMATAL CLOSURE
REACTIVE OXYGEN SPECIES
MAPK CASCADE ACTIVATION
CALLOSE DEPOSITION
Ca++ Influx
CORONATINE
CHEMICAL WEAPONS
COR+
COR-
Pst STRIKES BACK
We will talk
about this
next week
TTSS-
A) Col-0 leaves were exposed to water (white bars), Pst DC3000 (wavy bars), or the cor
mutant Pst DC3118 (gray bars). Bacterial concentration used was 1 3 108 cfu/ml.
Control of PAMP-triggered stomatal responses
Salicylate
Hydroxylase
PTI
•
•
•
•
•
•
STOMATAL CLOSURE
REACTIVE OXYGEN SPECIES
MAPK CASCADE ACTIVATION
CALLOSE DEPOSITION
Ca++ INFLUX
SALICYLIC ACID
PAMP TRIGGERED (INNATE)
IMMUNITY - PTI
SYSTEMIC ACQUIRED
RESISTANCE
Figure 1. P. syringae-induced resistance to P.
syringae. The photograph shows upper leaves of
plants inoculated with either water (A) or with P.
syringae (4x108 cells/ml) (B) on the lower leaves of
the rosette. Two days after infection of the lower
leaves, upper leaves were challenged with the same
pathogen (107 cells/ml). Leaves were photographed
Summermatter, et al., Plant Physiol. (1 995) 108: 1379-1 385
4 d after challenge.
PAMP TRIGGERED (INNATE)
IMMUNITY - PTI
SYSTEMIC ACQUIRED
RESISTANCE
Willow tree bark
Genus: Salix
BAYER
source: Taiz L., Zeiger E., 2010
Acetylsalicylic acid
CORONATINE
CHEMICAL WEAPONS
How does it work?
Pst needs to shut this
down!
Necrotrophic
Biotrophic
“Typically, the pathogen-induced pathway relies on salicylic acid produced by
the plant as a signalling molecule, whereas the herbivory-induced pathway
relies on jasmonic acid as the signalling molecule.”
CORONATINE:
A JASMONATE
ANALOGUE?
How does it work?
Nature Chemical Biology 5, 273 - 274 (2009)
“..Jasmonates can suppress the proliferation of human cancer cells and
induce their death. Methyl jasmonate induced death in breast and prostate
carcinoma cells, as well as in melanoma, lymphoma, and leukemia cells ”
Leukemia 2002; 16: 608–16
Pst
Plant
CHEMICAL WEAPONS
SABOTEURS
CORONATINE:
A JASMONATE
ANALOGUE
How does it work?
CHEMICAL WEAPONS
Remember Brittney’s AUX/IAA story?
CORONATINE:
A JASMONATE
ANALOGUE
COR
Remember Brittney’s AUX/IAA story?
Robert Nordsieck
Kästner et al., ICommunicative
& Integrative Biology 2014
7(1): e28728.
How does it work?
Questions?!
Next week: Effector Triggered
Immunity