1) The study evaluated how different genotypes of tall fescue and infection by different endophyte strains altered the plant's response to predicted climate change factors of increased heat, precipitation, and their combination. 2) Results showed that photosynthesis, biomass, tiller production, and alkaloid levels responded variably depending on the fescue genotype, endophyte presence, and climate treatment. In general, endophyte presence benefited the plant more for some genotypes than others. 3) The responses also varied seasonally and by climate treatment, with elevated heat generally reducing plant performance more than other factors. Overall, the study suggests choice of plant and endophyte genetics will influence how well fes

1. Ecophysiological Responses of
Tall Fescue Genotypes to
Endophyte Infection and
Climate Change
Tall fescue (Schedonorus arundinaceus) can form a
symbiosis with the fungal endophyte, Epichloë coenophialum,
whose presence can benefit the plant, depending on plant
and fungal genetics and prevailing environmental conditions.
Despite having agricultural, economic and ecological
importance, relatively little is known regarding how the
symbiosis will respond to predicted climate change. We
evaluated how plant genetics and endophyte presence
altered fescue response to predicted changes in climate.
Methods
Genetic clones of four KY-31 derived tall fescue individuals
infected with different common toxic (CTE14, CTE45) or
novel endophyte (NE16, NE19) strains were developed. Half
of the material was treated with Folicur 3.6F to produce
genetically identical endophyte-free individuals. Endophyte-
infected (E+) and -free (E-) genetic clones were transplanted
into an existing 2 x 2 factorial climate change experiment:
Control, +Heat (+3°C), +Precip (+30%), +Heat+Precip
(+3°C, +30%). The study was a randomized complete block
design with five replications. Photosynthesis, leaf water
potential, tiller number, aboveground biomass and ergot
and loline alkaloid concentrations were measured from
March to November 2012.
I would like to thank my advisor, Dr.
Rebecca McCulley for believing in me; my
committee: Dr. Dennis Egli, Dr. Tim
Phillips, Dr. Randy Dinkins, for their advice
and support; Jim Nelson and Elizabeth
Carlisle for technical and moral support;
Kristen McQuerry for her statistical
knowledge; Huihua Ji for her technical help
on alkaloid measurements and finally the
rest of the McCulley lab team and the
University of Kentucky.
Marie Bourguignon 1,2, Rebecca L. McCulley 2, Randy D. Dinkins2,Tim D. Phillips2,
Dennis B. Egli2, Jim A. Nelson2, Elizabeth Carlisle2 and Huihua Ji2
1 Dept of Agronomy, Iowa State University
2 Dept of Plant and Soil Sciences, University of Kentucky
Background
Conclusion Acknowledgements
Funding Source:
We hypothesized that fescue ecophysiological responses to climate
change factors would vary across plant genotypes and depend on
Epichloë presence. We predicted that endophyte infection would not
confer the same degree of environmental stress tolerance to all
fescue genotypes. Our results support these suppositions.
When averaged across the growing season, photosynthesis rates
were significantly impacted by elevated heat and increased
precipitation but in contrasting ways depending on the fescue
genotype and endophyte status. Often, E+ individuals performed
better than E-, except for leaf water potential, which was never
influenced by endophyte presence. Endophyte infection conferred
different levels of environmental stress tolerance to the different
fescue genotypes.
Overall, this study suggests that choice of plant and endophyte
genetic material will be important in determining the productivity and
resilience of fescue pastures under future climate conditions.
1
2
Results3
4 5
Figure 1: Abiotic, biotic factors and genetic controls on
the tall fescue – E. coenophialum symbiosis.
Figure 2: Experiment layout, UKY Research Farm, Lexington, KY.
Symbiotic Genotype per Treatment
C
TE14C
TE45N
E16N
E19
C
TE14C
TE45N
E16N
E19
C
TE14C
TE45N
E16N
E19
C
TE14C
TE45N
E16N
E19
Photosynthesis(mol.m-2.s-1)
0
5
10
15
20
25
30
E+
E-
Control +Heat +Precip +Heat+Precip
Genotype × Endophyte × Heat × Precipitation: 0.0387
A
ab
a
A
a
A
A
b
A
a
a
AB
B
b
B
ab
A
ab
A
ab
A
b
a
A
A
b
A
b
a
A
A
b
E+ = E-
E+ = E-
*
E+ = E-
AnnualAbovegroundBiomass(g.plant-1)
0
2
4
6
8
10
12
E+
E-
b
a
b b b b
b
b
Endophyte × Genotype: 0.0447
Symbiotic Genotype
CTE14 CTE45 NE16 NE19
TillerProduction(counts)
0
2
4
6
8
10
12
14
16
a
a
b
b b
b
b
b
Endophyte × Genotype: < 0.0001
Symbiotic Genotype per Treatment
Control +Heat +Precip +Heat+Precip
Treatment
Control +Heat +Precip +Heat+Precip
ErgotConcentration(ppm)
0.0
0.2
0.4
0.6
0.8
CTE14
CTE45
Genotype × Heat × Precipitation × Time: 0.0024
a
a
b
b
a
a
b
b
BC
A
C B
Fescue Genotype Variability:
• Endophyte infection greatly
stimulated aboveground biomass
production in CTE14, but had no
significant effect on the other
genotypes (Fig. 5-A).
• For tiller production, the same
endophyte-associated stimulation
was observed for both symbiotic
genotypes CTE14 & NE19 (Fig. 5-B).
Figure 4: Averaged across the study leaf water potential of
endophyte-free fescue for each genotype and each climate
treatment. Within a climate treatment, points with different lower
case letters are statistically different across genotypes; whereas
capital letters denote significant differences between treatments
within the same genotype
Figure 5: Aboveground biomass (A) and tiller
production (B) for E+ and E- fescue, averaged
across fescue genotypes, averaged across climate
treatments. Letters indicate significant differences
within a panel.
A
B
Fescue-Endophyte Symbiosis Variability:
• Ergot alkaloid concentrations were stimulated by elevated heat
for genotypes infected with a common toxic form of the
endophyte (Fig. 6-A). Effects of the +Heat and +Precip treatments
appeared to be additive.
• Photosynthesis was the most sensitive parameter measured, with
all experimental factors significantly affecting it (Fig. 6-B).
Elevated precipitation and endophyte presence increased overall
photosynthesis, whereas warming conditions negatively affected
it, but these responses were genotype dependent.
Figure 6: Ergot alkaloids or two fescue genotypes infected with a common toxic strain of
endophyte (A) and photosynthesis rates of E+ and E- fescue for all four genotypes (B) in
each climate treatment and averaged across the year, 2012. Lower case letters indicate
significant differences between genotypes (A) or endophyte status (B) within a climate
treatment; whereas capital letters illustrate differences across climate treatments (A) or
genotypes (B).
Plant Genetic Controls:
• Genotype 19 was more responsive to the
climate change treatments than the other
fescue genotypes. The response of leaf
water potentials and tiller production to
climate change varied across studied
genotypes (Fig. 4).
• Elevated heat and additional precipitation
tended to reduce tiller production, but the
degree varied by genotype (not shown).
In 2012, environmental conditions were much
hotter and drier than usual, affecting water
availability. All measured fescue responses,
except alkaloid concentrations, were
negatively impacted by additional heat,
especially in the summer.
Figure 3:
Weekly
average air
temperature,
precipitation,
and average
volumetric
water content
for the four
climate
treatments.
B
A
A
25-O
ct-2011
15-Nov-2011
6-Dec-2011
27-Dec-2011
17-Jan-2012
7-Feb-2012
28-Feb-2012
20-M
ar-2012
10-Apr-2012
1-M
ay-2012
22-M
ay-2012
12-Jun-2012
3-Jul-2012
24-Jul-2012
14-Aug-2012
4-Sep-2012
25-Sep-2012
16-O
ct-2012
6-Nov-2012
27-Nov-2012
WeeklyPrecipitation(mm)
0
50
100
150
200
250
300
WeeklyAirTemperature(°C)
0
20
40
60
VolumetricWaterContent(%)
-40
-20
0
20
40
Transplantation
Harvest1
Harvest2
Harvest3
Beginningof
Measurements
Endof
Measurements
Precipitation +Precip and +Heat+Precip
Precipitation Control and +Heat
Control
+Heat
+Precip
+Heat+Precip
Volumetric Water Content
Air Temperature
Treatment
LeafWaterPotential(MPa)
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5 Geno 14
Geno 45
Geno 16
Geno 19
Genotype × Heat × Precipitation: 0.0235
Control +Heat +Precip +Heat+Precip
bB
bB bB
aAB
bC
abC
aC
bC
aA
aA
aA
aA
bBC
bBC
bBC
aB