Resistance of potato genotypes to drought stress

Pankaj Banik, M.Sc. Student

University of Saskatchewan, Canada

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

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

Hypotheses

• Drought stress history of genotypes affects

subsequent drought stress resistance [V1002-2]

• Drought acclimation and recovery are key

components of resistance

[Fv12246-6, V1002-2 & Russet Burbank (RB)]

• 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 Drought Acclimation History induced

higher tuber numbers in 5-50g wgt classes

0 2 4 6 8 10 12 14 16

NA-NA

NA-DAS

NA-NAS

DA-NA

DA-DAS

DA-NAS

Tre

atm

en

ts

Tuber No.

<5g

5-20g

20-50g

50-100g

>100g

<5g 5-20g 20-50g 50-100g >100g

Treatment with No Acclimation History had

lowest leaf water content at maximum stress

74

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

Treatments

% le

af

wa

ter

co

nte

nt

Overall difference among treatments: ***

Recovery Stage:

Drought Acclimation History either in Generation 3 alone

or with combined Generations 1 + 2 induced lower rate of leaf

water loss compared to NA-NA-NA and NA-DAS-NA

0

5

10

15

20

25

30

35

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

Time (min)

% w

ate

r lo

ss

NA-NA-NA

NA-NA-DAS

NA-DAS-NA

NA-DAS-DAS

DA-DAS-NA

DA-DAS-DAS

A

B

Difference in leaf cuticle layer morphology over 3 successive generations

NA-NA-NA

(no stress history)

Stomata

DA-DAS-DAS

(Stressed over 3

generations)

Φ = 0.1mm2, 600X

Hypotheses

• Drought stress history of genotypes affects

subsequent drought stress resistance

• Drought acclimation and recovery are key

components of resistance

{Fv12246-6, V1002-2 & Russet Burbank (RB)}

• 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

Drought Acclimation did not increase total % leaf water

content at maximum stress.

74

76

78

80

82

84

86

88

90

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

Treatments

% l

eaf

wate

r co

nte

nt

HOWEVER, rate of water loss was affected.

Non-Acclimated (NA) treatments had highest rate of % leaf water loss.

Overall, V1002 lost water at a significantly higher rate than Fv12 & RB.

0

1

2

3

4

5

6

7

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

Time (min)

% w

ate

r lo

ss

Fv-NA

Fv-DAS

Fv-NAS

V-NA

V-DAS

V-NAS

RB-NA

RB DAS

RB NAS

NA

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

Summary

• Previous stress history • Induced more tubers in the 5 – 50 g size classes.

• Drought Acclimation

» Increased Leaf Water Content (LWC) under max. stress

» Reduced rate of % leaf water loss

» Difference in leaf cuticle layer

• No previous history • Drought Acclimation

Did not increase LWC

Did reduce rate of % leaf water loss

Had most significant effect on RB shoot responses

Next Experiments

• Stomatal aperture evaluation on NA, DAS

and NAS in drought history and no previous

drought stress history experiments.

• Water Use Efficiency, non-destructive Water

Potential measurements

• Specific response measurement in all six

genotypes received from Dr. Bizimungu.

Acknowledgements

Prof. Karen Tanino, University of Saskatchewan (U of S), Canada

Dr. Benoit Bizimungu, AAFC, Fredericton, NB.

Dr. Helen Tai, AAFC, Fredericton, NB.

Prasanto Mondol, PhD student, U of S

Prof. Sakti Jana, U of S

Eldon Siemens, U of S

Jackie Bantle, U of S

Thank you