Uncovering geospatial patterns of drought tolerance in Mimulus aurantiacus

Nneka NnatubeugoBowdoin College

University of Oregon – Summer Program for Undergraduate Research

Mentor: Dr. James Sobel

PI: Dr. Matthew StreisfeldFunded by the National Science Foundation

About Mimulus aurantiacus

• Red: marine influence: cooler, less seasonal, more days of cloud cover, less reason to be drought tolerant

• Yellow: seasonal, harsher, higher UV intensity, drier

M. aurantiacus var puniceus

M. aurantiacus var australis

Reason for separation: ability to withstand drought?

Or another combination of factors?

Research Question 1

•Are there differences in drought tolerance between the ecotypes?

• Hypothesis: Yellow more drought tolerant than red or hybrid

Experimental Design

Drought Tolerance • 16 populations - 6 red, 4 hybrid, 6 yellow • 189 maternal lines from populations• 9-17 lines / population

• Transplanted three replicates from each line into cones – 567 total plants

• Grew and watered until differentiation then stopped watering

• Used qualitative scale to measure appearance of drought stress

Experimental Design

Drought Tolerance • 16 populations - 6 red, 4 hybrid, 6 yellow • 189 maternal lines from populations• 9-17 lines / population

• Transplanted three replicates from each line into cones – 567 total plants

• Grew and watered until differentiation then stopped watering

• Used qualitative scale to measure appearance of drought stress

4 0 1 2 3

p= 0.0011

Yellow ecotype is more drought tolerant than red ecotype

dead

Healthy

Yellow ecotype is more drought tolerant than red ecotype

p= 0.0011

dead

Healthy

Research Question 2

•Which traits contribute to differences in drought tolerance? •Leaf Area, Resin, Anthocyanin

Factors that affect drought tolerance

Experimental Design

• Resin & Anthocyanin • Transplanted 2 plants per line into 2 ¾

inch pots • Grown for 1.5 months and then sampled:• Extracted resins and anthocyanin from

leaves • Analyzed concentrations of resin and

anthocyanin via UV spectrophotometry

• Leaf Area• Used program ImageJ to quantify

Red ecotype produces more anthocyanin than hybrid or

yellow

p=0.0105

red hybrid yellow0.13

0.135

0.14

0.145

0.15

0.155M

ean

An

thoc

yan

in C

once

ntr

atio

n

Red ecotype produces more resin than hybrid or yellow

p=0.0099

red hybrid yellow0.4

0.42

0.44

0.46

0.48

0.5

0.52

0.54

0.56M

ean

res

in c

onc.

Red ecotype has greater leaf area than hybrid or yellow

p= 0.0055

red hybrid yellow0

2

4

6

8

10

12

14M

ean

Lea

f ar

ea

Plants with greatest leaf area die fastest

DAY 4

DAY 5 DAY 6 p=0.2838; R2= 0.00614 p<0.0001; R2=0.11 p<0.0001; R2= 0.154848

dying

dying

dying

alive

alive

alive

• Yellow ecotype more drought tolerant than red ecotype

• The largest percent of variation in drought tolerance is explained by leaf area

Future Directions

• Measure vegetative anthocyanin and resin when the plants are stressed to see how the concentrations compare with the unstressed concentrations• Measure drought and correct for the effect

of leaf area in order to see how much of an impact ecotype has on the drought assessment

Acknowledgements

• Streisfeld Lab:• Matt Streisfeld• Jay Sobel• Josh Bahr

• SPUR:• Peter O’Day• Adam Unger• Fellow SPUR interns