Transcript LTER example

US NSF LTER sites
US NSF National Ecological
Observatory Network
• New network for addressing major ecological
questions, with Infectious Disease as one major
theme
• Planning for the next 30 years
• General website www.neoninc.org
• Website with latest reports from topics
committees (prior to specifying particular
systems) :
http://www.neoninc.org/archive/2005/04/latest_
neon_des.html#more
Long-term foliar
infection in
tallgrass prairie
plants
Tallgrass prairie
in central USA
Not as flat as a pancake
Flint Hills, Kansas, USA
3,487 Ha
Burn Interval
Variable
Annual
2 year
4 year
10 year
20 year
Grazing
Bison
Cattle
KONZA PRAIRIE
BIOLOGICAL STATION
N
Long-term plant species
composition data
• Long-term data set with complete plant
species cover classes collected in many
environments at Konza Prairie
• See www.konza.ksu.edu
Sampling scheme within a transect
for plant species composition assessment
•Five quadrats are located along each transect
•In general, four upland transects and four lowland
transects are present in each watershed
Precipitation manipulation – RaMP project
Most important environmental effects
• Burning is not so important across species
(during drought years), but is for some
particular species
• Position on slope is the most important
environmental predictor
• Grazing effects were quite specific to hostpathogen system
• Host frequency dependence was indicated
Overall effects of burning (during 3 drought years)
0.9
Proportion of plant diseased
0.8
56
0.7
56
56
0.6
0.5
0.4
2
2
0.3
2
0.2
4
40, 90
0.1
4
40, 4, 90
127
0.0
1
Code : Species
2
Andropogon gerardii
4
Bouteloua curtipendula
40
Amorpha canescens
56
Asclepias viridis
90
Lespedeza capitata
127 Solidago canadensis
4
Burning Clycle (Years)
20
Comparisons : P-value
1 vs 4 : 0.19
1 vs 20 : 0.07
4 vs 20 : 0.01
Effects of burning on
rust of Erigeron strigosus
50
% Leaves infected
unburned
40
burned
30
20
10
0
2000
2001
2002
Year
2003
2004
Dendy et al., in preparation
Topographic effect on
big bluestem rust
• Rates of infection by
Puccinia
andropogonis are
greater for midslope
sites than bottom or
AUDPC
crest sites (P≤0.05)
Percent infected leaves
20
15
Midslope
Bottom
10
Crest
2.95 a
Mid
7.02 b
Bottom 4.22 a
5
0
28-May 11-Jun 25-Jun
Crest
9-Jul
23-Jul 6-Aug 20-Aug
Morgan, Garrett, Todd, and Tisserat (in revision)
• A community
epidemiology approach
studying the responses of
visually-distinguishable
pathogens of 20
dominant tallgrass prairie
plant species
• Responses to burn return
time and topography are
less consistent from one
host-pathogen system to
another and may
contribute to stability of
plant productivity
Disease Incidence in Nonirrigated Transects
Precipitation effects on disease
1
16
0.8
0.6
12
0.4
18
19
5
0.2
24
17
0
0
0.2
0.4
0.6
0.8
Disease Incidence in Irrigated Transects
Garrett et al. (in preparation)
1
Flowering in Dalea candida as a
function of precipitation level
and leaf rust infection
Mean Inflorescence Size
(mm)
14
12
Irrigated
Non-Irrigated
10
2000
8
2001
6
2002
4
2
0
Uninfected
Garrett et al. (in preparation)
Infected
Uninfected
treatm ent
Infected
Movement of pathogens between agricultural
and natural systems and external pathogen
populations
Agricultural (Managed) System
Environment
Host
Natural (Unmanaged) System
Plant
community
Environment
Pathogen
community
Pathogen
External
pathogen
community
BYDV infection in native grasses
• First report of BYDV/CYDV in these grass species: percentage
infection based on at least 50 plants of each species
• PAV is the most common strain in wheat, but was not
recovered from the grasses at Konza Prairie
• In wheat, infection rates by the “tallgrass prairie” strains were
common adjacent to prairie but fell off 30 m into wheat fields
Grass species
PAV
MAV
RMV
RPV
SGW
Indian grass
0
0
0
0
0
Little bluestem
0
4
2
0
58
Switchgrass
0
31
0
0
4
Big bluestem
0
59
0
0
3
Garrett, Dendy, Power, Blaisdell, Alexander, and McCarron 2004 Plant Disease
Susceptibility of native grasses
to take-all
Grass species
Response
Big bluestem
R
Little bluestem
R
Indian grass
R
Switchgrass
R
Sideoats grama
S
Blue grama
S
Buffalo grass
S
• Native grass seedlings
showed nearly complete
resistance or
susceptibility to the takeall pathogen
• Exchange between
agricultural and natural
systems needs study
• In grasslands there is the
potential for apparent
competition via shared
pathogens
Cox, Garrett, Bockus, and Fang (in review)
Ecological genomics and
epidemiology
Pathogen genome(s)
Pathogen species
Host species
Host genome(s)
Garrett et al., in review
Abiotic environment
(and biotic environment)
Community metagenome
and abiotic environment
In a study of the dominant tallgrass
prairie plant species, Andropogon
gerardii, we have been able to detect
responses to simulated precipitation
change in the field using maize
microarrays
Treatment effects
10
8
Travers et al., in review
-log10 (P)
6
4
Q < 0.05
2
0
-8
-6
-4
-2
0
2
log2(fold change)
4
6
8
Systemic acquired resistance
• (Need nomenclature for new forms of
resistance as they are understood)
• Infection with an incompatible pathogen, or
virulent pathogen that causes cell death, can
make a plant more resistant to subsequent
infection by the same or different pathogens
– SAR response in Arabidopsis confers resistance to
several diseases (Ryals et al. 1996)
Induced systemic resistance
• Resistance to pathogens can be influenced by
non-pathogenic organisms
• Systemic changes in disease resistance in
response to colonization by rhizospherecolonizing Pseudomonas have been welldocumented (Iavicoli et al. 2003, Cui et al.
2005)
• Dissection of SAR and ISR signaling systems in
Arabidopsis indicate they are controlled by
different pathways and signaling molecules with
some common components
Landscape ecological genomics
Host individual
Host
landscape
“Plant-wide” gene expression
Genotype
“Organ-wide” gene expression
Pathogen
landscape
Local gene expression
Environmental
landscape
Local phenotype
Garrett et al., in review