oral talk in 'botany 2015
TRANSCRIPT
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Effect of drought acclimation on drought stress resistance in
potato (Solanum tuberosum L.) genotypes
Pankaj Banik and Karen Tanino
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Potato plants are sensitive to drought stress
Sensitive to drought (van Loon 1981)
Even a short period of water stress
• Tuber quality and production
Critical stages (Onder et al. 2005)
• Stolon elongation
• Tuber initiation
• Delays tuber formation
• Decrease in tuber number, growth & yield
4 flower stage
( in cymose
inflorescence)
0
5
10
15
20
25
30
35
So
il m
c, %
1st DA 2nd DA 1st DS 2nd DS 1st DS-R 2nd DS-R
Drought Acclimated & Drought Stressed (DAS)
Non-Acclimated & Drought Stressed (NAS)
Non-Acclimated & Non-Stressed (NA)
5 days 7-10 days 5-7 days
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Hypotheses Pre-exposure to water deficit will induce drought
acclimation in potato genotypes
There are genotypic differences in drought stress resistance
Leaf and stem characteristics will distinguish genotypes and ability to acclimate to drought stress
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Potato genotypes used
AAFC Potato breeding program, Lethbridge AB
• Fv12246-6 (Fv)
• ‘Vigor’ (V)
• ‘Russet Burbank’ (RB)
0
50100
150
200250
300
350400
Fv V RB NA DAS NAS
Genotype Treatments
Tu
be
r w
t./p
ot,
g
0
5
10
15
20
25
30
Fv V RB NA DAS NAS
Genotype Treatment
Tu
be
r n
um
be
r/p
ot
0 5 10 15 20
Fv
V
RB
NA
DAS
NAS
Fv
V
RB
NA
DAS
NAS
Fv
V
RB
NA
DAS
NAS
Fv
V
RB
NA
DAS
NAS
Fv
V
RB
NA
DAS
NAS
<5
g5-2
0g
20-5
0g
50-1
00g
<100g
Tuber number
RB had higher tuber weight than Fv
Highest tuber number in ‘Vigor’ was a result of <5g category
There was no drought acclimation effect of tuber weight & number, BUT
Drought Acclimation DID induce a differential response in leaf wilting. Drought Acclimation reduced leaf wilting under drought stress in RB.
Fv was sensitive to leaf wilting.
Leaf wilting is the most visual index of
drought stress
What is the mechanism of
acclimation to reduce leaf wilting?
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
DAS NAS DAS NAS
Fv RB
Inc
rea
sin
g w
ilti
ng
sc
ore
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Drought resistance mechanisms Water
management
Increasing
water uptake
Reducing
water loss
Leaf
characteristics
Stem
characteristics
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Drought Acclimation induced the thickest leaf epicuticular layer
0
50
100
150
200
250
300
350
400
Fv RB NA DAS NAS
Genotype Treatment
Th
ick
ne
ss
of
lea
f w
axy l
aye
r, µ
m
Acclimation and a series of stresses (DAS & NAS) induced smaller pavement cells compared to controls (NA) in both genotypes
RB-NA RB-DAS RB-NAS
0
100
200
300
400
500
600
700
800
NA DAS NAS NA DAS NAS
Fv RB
Are
a o
f e
pid
erm
al c
ell
, µ
m2
Drought stress induced smaller stomata
Stomatal size did not
change in RB treatments
0
50
100
150
200
250
300
350
400
NA DAS NAS NA DAS NAS
Fv RB
Are
a o
f s
tom
ata
, µ
m2
0
5
10
15
20
25
30
NA DAS NAS NA DAS NAS
Fv RB
Are
a o
f sto
mata
l p
ore
, µ
m2
Drought acclimation induced more open
stomata
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Recovery Time: RB (5 hrs), V (12 hrs) and Fv (16 hrs)
Fv
Recovers
23 oC 22.6 oC 21.1 oC 20.6 oC
Maximum stress After 16 hrs of watering
NAS DAS NAS DAS
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Literature on drought stress focused:
• Leaves & roots
• What about STEM ?
To distinguish the effect of the main stem:
Stress was imposed: • On intact leaves on stem
• Excised leaves
Drought resistance mechanisms
Water
Management
Increasing
water uptake
Reducing
water loss
Leaf
characteristics
Stem
charactersitics
86
87
88
89
90
91
92
93
94
95
Fv V RB% S
tem
wa
ter
co
nte
nt
Genotype
78
80
82
84
86
88
90
Fv V RB
% L
ea
f w
ate
r c
on
ten
t
Genotype
When intact leaves on stems were stressed
V/RB had higher %LWC than Fv at maximum soil water deficit
Higher %Stem Water Content in V/RB than Fv
= greater %LWC ?
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Fv V RB
Av r
ate
of
wa
ter
los
s,
mg
/min
Genotype
When excised leaves (minus the stem) were stressed: V lost water by the highest rate
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Stem water might represent a water source to leaves during drought stress
Leaves INTACT
on the stem EXCISED from the stem
drought stress drought stress
V & RB had higher
%LWC than Fv
V lost water by the
highest rate
Stem > access to more
stored water for drought
stressed leaves
V, RB had > %stem
water content than Fv
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No difference in the length of xylem and pith between Fv and V Source of additional %SWC did not relate to the length of xylem and pith
0
500
1000
1500
2000
2500
3000
3500
4000
Fv V RB NA DAS NAS
Genotype Treatment
Le
ng
th o
f x
yle
m a
nd
pit
h,
µm
Xylem
Pith
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Summary
Ge
no
typ
e
Hig
he
r w
eig
ht
or
tub
er
nu
mb
er
Drought resistant tools
Type
Reduced
Leaf
wilting
under
stress
Higher
%leaf
wc
under
stress
Higher
%Stem
wc
Smaller
Stomata
under
stress
Acclimation-
induced more
open stomata
Smaller
leaf
pavement
cells
under
stress
Equivalent
Pith and
Xylem
length
Faster
Recovery
from
maximum
stress
RB √ √ √ √ X √ √ √ √ Resistant
Fv X X X X √ √ √ X X Sensitive
V √ √ √ √ ? ? ? X √
X
Moderate
resistant
Hypotheses I There are genotypic differences in drought stress resistance II Stem & leaf characteristics distinguish genotypes & ability to acclimate to drought stress
Most resistant type (RB) had the greatest number of
drought resistant tools (√)
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Summary
Reduced
Leaf wilting
More open stomata
under stress
Thicker leaf
epicuticular wax
under stress
Non-Acclimated and
Drought Stressed (NAS) X X X
Drought Acclimated and
Drought Stressed (DAS) √ √ √
Without a DAS approach,
potentially key drought stress resistance mechanisms
will be MISSED
Hypothesis III Pre-exposure to water deficit will induce drought acclimation in potato genotypes
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Acknowledgements
Supervisor
Prof. Karen Tanino
Advisory committee
Prof. Yuguang Bai
Prof. Tom Warkentin
Prof. Gordon Gray
Funding agency
SAGES Project
Greenhouse Team
Eldon Siemens
Jackie Bantle
SEM
Guosheng Liu
Rob Peace
Confocal / microscopy
Shanna Benmann
Louise Elisabeth Arve
Prof. Jorunn Olsen
Statistics
Prof. Sakti Jana
Prasanto Mondol
Ting Wei
Spatial analysis
Dr. Winston Zeng
Ting Wei
Lab members
Terri Lynn Paulson
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Thank you
Questions ?