Drought stress in potato plants

Pankaj Banik, Winston Zeng, Helen Tai and Karen Tanino

Drought Stress

• Most adverse factor to plant growth and

productivity

• Single most critical threat to world food security

• 40% of world’s land

– Arid and semi-arid zones

• Water is the most limiting factor to plant productivity

Potato (Solanum tuberosum L.)

• Origin: Ecuador and Peru

• 4th most important food crop

– More than 150 countries

• Different climatic zones, agro-economic conditions & altitudes

• Major horticultural crop in Canada

• Herbaceous C3 annual plant

Nutrient content / 100g

Source: USDA National

Nutrient Database

Drought stress in potato plants

• Sensitive to drought

– Even a short period of time

• Tuber quality & production

• Stolon formation & tuberization

– Most sensitive stage

• Longer period in tuber formation

• Decrease in tuber number, growth & yield

4 flowering stage

Greenhouse Low RH room

(22/20°C, 17-25% RH, 250 µmol/m2/sec)

Applying drought stress

0

5

10

15

20

25

30

35

So

il m

c%

1st DA 2nd DA 1st DS 2nd DS 1st R 2nd R

Drought acclimated & stressed (DAS)

Non acclimated but stressed (NAS)

Non acclimated & non stressed (NA)

Stress & Recovery

Severe stress (scale 3)

After recovery (scale 0)

Score % leaves wilted

0 None

1 25%

2 50%

3 75%

4 100%

5 Plant died

Measurements

• Leaf WC

• Stomatal aperture

• Water Use Efficiency

• Leaf water loss over 15 minutes

• Leaf temperature

• Leaflet water content

• Flowering time

• Stem diameter and plant height

• Biomass

• Trichome Number

• Leaf cuticle layer

• Yield

Applying drought stress

1 1

1 1

2 2

2 2

3 3

3 3

4

4

4

4 5 5

6

7

8

9

Hypotheses

• Drought stress history of genotypes affects

subsequent drought stress resistance

• Drought acclimation and recovery are key

components of resistance

• Stomatal aperture parameters are associated with

yield under drought stress conditions

Drought stress History over 3 generations

Generation 1 NA

(Non Acclimated)

DA

(Drought Acclimated)

Generation 2 NA-NA NA-DAS NA-NAS DA-NA DA-DAS DA-NAS

Generation 3 NA-NA-NA NA-DAS-NA NA-NAS-NA DA-NA-NA DA-DAS-NA DA-NAS-NA

NA-NA-DAS NA-DAS-DAS DA-DAS-DAS

NA-NA-NAS NA-DAS-NAS DA-DAS-NAS

}

}

}

Previous acclimation history in 2 generations induced

significantly higher yield compared to germplasms having no

previous history and/or history in one generation

0

200

400

600

800

1000

1200

1400

NA-NA-NA NA-NA-DAS NA-NA-NAS NA-DAS-NA NA-DAS-DAS NA-DAS-NAS DA-DAS-NA DA-DAS-DAS DA-DAS-NAS

Mea

n va

lue

of y

ield

, g (t

otal

mas

s of t

uber

s per

pot

)

Treatments

ade

be

be

bd

b

be

c

acac

3 generations > 2/1 genarations

1 generation: not enough

No history: no higher yield

Drought acclimation history in 2 or more

generations induced more tubers

0

5

10

15

20

25

30

35

40

NA-NA-NA NA-NA-DAS NA-NA-NAS NA-DAS-NA NA-DAS-DAS NA-DAS-NAS DA-DAS-NA DA-DAS-DAS DA-DAS-NAS

Mea

n va

lue

of g

ross

tube

r num

ber

Treatments

adad

ac

aa

a

b

bc

bcd

2 generations of drought acclimation were required to induce

higher leaf water content compared to germplasm without any

acclimation history at maximum stress

76

78

80

82

84

86

88

NA-NA-NA NA-NA-DAS NA-NA-NAS NA-DAS-NA NA-DAS-DAS NA-DAS-NAS DA-DAS-NA DA-DAS-DAS DA-DAS-NAS

Leaf

wat

er co

nten

t (%

)

Treatments

ae

b

ab

e

ae

ae

de

ade ade

Excised leaf moisture loss over 15 minutes

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

% le

af w

ater

loss

Time (min)

NA-NA-NA

NA-DAS-NA

NA-DAS-DAS

DA-DAS-NA

DA-DAS-DAS

Germplasm with previous acclimation history lost water

at a higher rate than germplasm with no history at early

stage but at higher / equal rate at later stage

Cycle Rate of water loss over 15 minutes

Tuber

initia

tion

DA-DAS-NA > DA-DAS-DAS > NA-NA-NA

DA-DAS-NA

>

NA-NA-NA

DA-DAS-DAS

>

Tu

ber

bulk

ing DA-DAS-DAS

>

NA-NA-NA

>

DA-DAS-NA

NA-NA-NA

DA-DAS-DAS

DA-DAS-NA

Summary

• Germplasm having acclimation history in

previous 2/3 generations induced: • higher yield & tuber number

• Higher LWC

• Lost water at a lower rate

• To reinforce:

– Stomatal size and opening

– Leaf cuticle layer thickness

Hypotheses

• Drought stress history of genotypes affects

subsequent drought stress resistance

• Drought acclimation and recovery are key

components of resistance

• Stomatal aperture parameters are associated with

yield under drought stress conditions

Experiment layout (no stress history)

Genotypes Treatments Codes

Fv12

NA (Non Acclimated) Fv-NA

DAS (Drought Acclimated & Stressed) Fv-DAS

NAS (Non Acclimated & Stressed) Fv-NAS

V1002

NA V-NA

DAS V-DAS

NAS V-NAS

RB

NA RB-NA

DAS RB-DAS

NAS RB-NAS

Russet Burbank induced highest yield followed by Fv12 &

V1002. Drought acclimation did not induce higher yield.

0

200

400

600

800

1000

1200

NA DAS NAS NA DAS NAS NA DAS NAS

Fv12 V1002 Russet Burbank

Mea

n yi

eld

(mas

s pe

r pot

), g

Genotypes & treatments

Russet Burbank & V1002 had higher LWC than Fv12 at maximum

stress. Acclimation did not induce higher LWC.

74

79

84

89

94

99

NA DAS NAS NA DAS NAS NA DAS NAS NA DAS NAS NA DAS NAS NA DAS NAS

Fv1002 V1002 Russet Burbank Fv1002 V1002 Russet Burbank

1st DS 2nd DS

Leaf

wat

er co

nten

t, %

Early vegetative stages : Acclimation induced lower rate in early vegetative stage but

maintained equal rate at later stage. Upon recovery from Drought Stress, Acclimation

induced a higher rate. V1002 > Fv12 > Russet Burbank (RB).

0

1

2

3

4

5

6

7

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

% le

af w

ate

r lo

ss

Time (min)

Fv-NA

Fv-DAS

Fv-NAS

V-NA

V-DAS

V-NAS

RB-NA

RB-DAS

RB-NAS

Drought Acclimation had the most significant

impact in RB shoot-related responses.

0

2

4

6

8

10

12

14

16

Fv NA Fv DAS Fv NAS V NA V DAS V NAS RB NA RB DAS RB NAS

Final stem diameter

0

1

2

3

4

5

6

7

Fv NA Fv DAS Fv NAS V NA V DAS V NAS RB NA RB DAS RB NAS

Final stem No.

0

20

40

60

80

100

120

140

160

180

Fv NA Fv DAS Fv NAS V NA V DAS V NAS RB NA RB DAS RB NAS

Final shoot dry wt

0

50

100

150

200

250

Fv NA Fv DAS Fv NAS V NA V DAS V NAS RB NA RB DAS RB NAS

Final plant height

Drought acclimation increased WUE over controls. RB

maintained highest WUE.

Treatments ∆

Fv-NA 20.74

Fv-DAS 21.89

Fv-NAS 19.83

V-NA 22.71

V-DAS 22.43

V-NAS 20.33

RB-NA 20.25

RB-DAS 20.56

RB-NAS 18.57

Fv-DAS V-DAS RB-DAS

Fv-NAS V-NAS RB-NAS

Preliminary SEM results showed differences in cuticular

and stomatal morphology

-500

0

500

1000

1500

2000

2500

3000

Fv-NA Fv-DAS Fv-NAS RB-NA RB-DAS RB-NAS

Area

of st

omat

al op

enin

g (µm

2 )

Treatments

a

ab

c

ac

ae

bc

Overall highly significant difference (p<0.001) among treatment groupsFv12: NA > NAS *** , DAS > NAS ***RB: DAS > NAS ***

Stomatal aperture (400X)

Acclimation induced

wider stomatal opening at

maximum stress

Acclimation induced

smallest stomatal size

in Fv12. Stomatal size

did not change in RB

treatments

0

5000

10000

15000

20000

25000

30000

35000

40000

Fv-NA Fv-DAS Fv-NAS RB-NA RB-DAS RB-NAS

Size

of s

tom

ata

(µm

2 )

Treatments

a

b

c

c

c c

Overall highly significant difference (p<0.001) among treatment groupsFv12: NA > NAS > DAS

Acclimation and a series of stresses induced smaller cuticle

platelet size compared to controls

0

10000

20000

30000

40000

50000

60000

70000

80000

Fv-NA Fv-DAS Fv-NAS RB-NA RB-DAS RB-NAS

Area

of cu

ticle p

latele

ts, mi

cron

Treatments

a

b

bc

a

b

b

Overall highly significant difference (p<0.001) among treatment groups Both genotypes: NA is significantly higher than both DAS & NAS

RB-NA RB-DAS RB-NAS

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Fv-NA Fv-DAS Fv-NAS RB-NA RB-DAS RB-NAS

Area

of xy

lem

vess

el (µ

m2 )

Treatments

a

b

ab

ab

ab

ab

Overall significant difference (p<0.05) among treatment groups

Stem cross-section (25X)

Xylem cross-section (250X)

Xylem vessel area measured were not related to drought acclimation. But stem

%WC was significantly different among genotypes and treatments

80.0

82.0

84.0

86.0

88.0

90.0

92.0

94.0

96.0

98.0

Fv-NA Fv-DAS Fv-NAS V-NA V-DAS V-NAS RB-NA RB-DAS RB-NAS

Stem

wat

er co

nten

t (%

)

Treatments

Overall highly significant difference (p<0.001) among genotypes & treatment groupsV1002 > Fv12 ***, RB > Fv12 ***

aj

deg

ab

cj

dj

aefj

gj

ehj

aih

22.3 oC 24.2 oC

NAS DAS

Maximum stress

(soil mc is 0% over 1 week)

Russet

Burbank

recovers

After 5 hrs of watering

NAS DAS

19.5 oC 19.6 oC

V1002 recovers within 12 hours

Fv takes 16 hours

Russet Burbank (RB) recovers much more quicker than

Fv12 & V1002 after undergoing maximum drought stress

Summary

• Under drought stress, drought acclimation

induced: – more small tubers

– higher WUE over controls

– Smallest stomatal size in Fv12

– More open stomata at maximum stress

– Smaller cuticle platelet size over controls

• Recovery rate from severe stress:

– Russet Burbank had fastest recovery time (5 hrs)

after stress followed by V (12 hrs) and Fv (16 hrs)

Acknowledgements

Supervisor

Prof. Karen Tanino

Funding agency

SAGES Project

Committee

Prof. Bruce Coulman

Prof. Tom Warkentin

Prof. Gordon Gray

Greenhouse Team

Eldon Siemens

Jackie Bantle

SEM

Guosheng Liu

Rob Peace

Mass Spec

Darin

Myles Stocki

Statistics

Prof. Sakti Jana

Prasanto Mondol

Spatial analysis

Dr. Winston Zeng

Ting Pei

Lab members

Jun Liu

Jihua Xu

Thank you