Drought imparts injuries in plant through elevated production of reactive oxygen species viz. (O2•, OH•, H2O2 and 1O2). Potassium (K) triggers numerous ameliorative functions against oxidative damages caused by drought. To investigate K attenuating oxidative damage and promotion of antioxidant defense in wheat (Triticum aestivum L. cv. BARI Wheat-21), an experiment was carried out at the Laboratory of Plant Stress Responses, Faculty of Agriculture, Kagawa University, Japan, under controlled environment of green house during June, 2017 to December, 2017.

1. “Potassium-induced antioxidant defense and regulation of
physiological processes towards drought stress tolerance in wheat”
Presented By
Abdul Awal Chowdhury Masud
Masters in Agronomy
Sher-e-Bangla Agricultural University
17th Conference of BSA
Date: 1 December, 2018
Venue: Bangabandhu Sheikh Mujibur Rahman
Agricultural University (BSMRAU)

2. Presentation Outline
 Introduction
 Objectives
 Materials & Methods
 Results & Discussions
 Conclusion
 Recommendations
 Q & A
2

3. Introduction

4. Wheat
 Major cereal crop under the Poaceae family
 Global Rank 1, Production & Consumption
 30% area is covered by wheat (Lobell and Gourdji, 2012)
 In 2016, world wheat production was 749 million tons, (FAOStat,
2016)
 By 2050, will require 60% more than today
4

5. Use of Wheat
Source: FAOStat,2018
Fig.1 Diversified use of wheat, worldwide
5

6. Wheat in Bangladesh
 2nd most significant grain crop after Rice
 In 2016-2017, Production was 1.42 million metric tons, an average
3.32 metric t/ha (DAE, 2018)
 Still 75% wheat consumption meets through imports
6

7. Wheat in Bangladesh
7
Fig.2 wheat scenario of Bangladesh (81-2000)

8. Currently
7.5 Bln
Fig.3 World population since 1700 (billions)
8

9. Stress?
Unfavourable conditions
that affects or blocks a
plant’s metabolism, growth
or development
(gaspar et al., 2002)
Adverse situation that
create mental or emotional
strain
9

10. Plant
10

11. Nutrient
Imbalance
Water
stress
Mechanical
stress
Temp.
stress
Pollutants
Radiation
(Light,UV)Heavy
Metal
Salinity
Fig.4 Diverse types of abiotic stresses
Drought
Abiotic
Stress
11

12. 12

13. Drought: World Scenario
 Already affected 35% of the world’s agricultural land
 Drought prone: currently approx. 26% of world arable land
 Limits >50% of world agricultural productivity
(Hasanuzzaman et al., 2017)
 Each year 12 million hectares are lost by drought and
desertification , extra 20 million tons grain could grown
(FAO, 2014)
13

14. What happens, while
Plant got stressed ??
What is oxidative
stress??
14

15. ROS
Reactive oxygen species
(1O2, O2
-,OH-,H2O2)
Antioxidants
Enzymatic
(APX, CAT,
GPX, GR)
Non-Enzymatic
(AsA, GSH, Proline)
Balance
Normal Plant
15

16. Imbalance
Stressed Plant
16

17. How drought creates oxidative stress?
Drought
(reduced water
availability)
ABA signaling
Stomatal closure
Diminished CO2 influx
ROS Production
Oxidative
Stress
17

18. How to overcome drought?
1. Selection and
breeding strategies
2. Molecular and
genomic approaches
3. Avoidance
techniques
Seed priming
Heat/ Cold Treatment
Early or late sowing
Exogenous Protectants
18

19. Plant Protectants
Molecules that have the potential to protect the plants from the
harmful effects of stress
Osmoregulators
 Proline
 Trehalose
 Glycine betaine
Phytohormones
 Auxin
 Abscisic acid
 Gibberellins
 Salicylic acid
Signaling
molecules
 H2O2
 Nitric oxide
Antioxidants
 Ascorbic acid
 Glutathione
 α-Tocopherol
Trace elements
 Micronutrients
 K, Ca, Mg, S, Zn,
Mo, Cu, etc.
Polyamines
 Arginine
 Ornithine
 Spermidine (Hasanuzzaman et al., 2013)
19

20. Why we used Potassium?
 Potassium has regulatory function in protein synthesis,
carbohydrate metabolism, and enzyme activation
 Improves stomatal movements & water status in plant
(Oddo et al., 2012)
 Increases root surface area that enhances the water
uptake by plant cells during drought
(Römheld et al., 2010)
 K upregulation reduces ROS generation in plants
(Hasanuzzaman et al., 2018)
20

21. Objectives
To observe the effect of drought on physiology of wheat plant
Role of exogenous K in alleviating drought effect in wheat
To observe K responses on oxidative stress markers and antioxidant
defense system under drought stress in wheat
21

22. Materials & Methods

23. Materials and methods
Plant material Wheat (Triticum aestivum L.) cv. BARI Gom 21
Experimental procedure
 Location Green house, Kagawa University, Japan
 Nutrient solution Hogland nutrient solution
 Growing media Sand
 Wegner pot For growing plants (d 10* h 11 inch)
 Design RCBD
 Duration 30 days
• 21-d-old seedlings were exposed to drought treatment
• Data were taken after 9 days drought treatment
23

24. Materials and methods
Factor: 2
Potassium (0 mM, 6 mM, 12 mM)
Drought (well watered, 50% FC, 20% FC)
Treatments: 9
 Well watered -K
 Well watered +K
 Well watered +2K
 50% FC -K
 50% FC +K
 50% FC +2K
 20% FC -K
 20% FC +K
 20% FC +2K
Control(field Capacity) 50% Field capacity 20% Field capacity
Replications: 3
24

25. Data collection
 Plant height
 Fresh weight & dry weight
 Relative water content RWC%
 Chlorophyll content
 Lipid peroxidation (MDA)
 Hydrogen peroxide (H2O2)
 Methylglyoxal
 Proline content
 Total soluble protein
 Ascorbate, Glutathione
 Root-shoot K content
Enzyme activities
APX, MDHAR, DHAR
GR, CAT, GPX
Determination of….
25

26. Results & Discussion

27. Effect of drought
27
Control-K 50%FC-K 20%FC-K Control+K 50%FC+K 20%FC+K
Control+2K 50%FC+2K 20%FC+2K

28. Effect of Potassium
28
Control-K Control+K Control+2K 50%FC+2K 50%FC+K 50%FC-K
20%FC-K 20%FC+K 20%FC+K

29. Effect on growth parameters
Treatments Plant height (cm) FW (mg/seedling) DW (mg/seedling)
Well-watered -K 32.21±1.66d 1.38±0.07c 0.18±0.010de
Well-watered +K 39.88±1.40b 1.50±0.06b 0.22±0.008b
Well-watered +2K 42.32±1.63a 1.66±0.04a 0.24±0.006a
50%FC -K 30.43±1.79e 1.23±0.04d 0.17±0.009ef
50%FC +K 35.07±2.14c 1.35±0.04c 0.19±0.011cd
50%FC +2K 39.13±1.61b 1.42±0.06bc 0.19±0.008c
20%FC -K 29.14±2.01f 1.11±0.06e 0.15±0.007g
20%FC +K 34.26±1.93c 1.23±0.06d 0.17±0.005ef
20%FC +2K 29.90±1.42ef 1.21±0.05de 0.16±0.004f
Treatments Plant height (cm) FW (mg/seedling) DW (mg/seedling)
Well-watered -K 32.21±1.66d 1.38±0.07c 0.18±0.010de
Well-watered +K 39.88±1.40b 1.50±0.06b 0.22±0.008b
Well-watered +2K 42.32±1.63a 1.66±0.04a 0.24±0.006a
50%FC -K 30.43±1.79e 1.23±0.04d 0.17±0.009ef
50%FC +K 35.07±2.14c 1.35±0.04c 0.19±0.011cd
50%FC +2K 39.13±1.61b 1.42±0.06bc 0.19±0.008c
20%FC -K 29.14±2.01f 1.11±0.06e 0.15±0.007g
20%FC +K 34.26±1.93c 1.23±0.06d 0.17±0.005ef
20%FC +2K 29.90±1.42ef 1.21±0.05de 0.16±0.004f
Mean (SD) was calculated from three replicates for each treatment. values with different
letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test
Table 1: Drought & K effect on plant growth parameters
29

30. Effect on leaf RWC%
cd
d
e
ab
bc
d
a
bc
e
0
20
40
60
80
100
120
Well water 50% FC 20% FC
Leafrelativewatercontent(%)
K- K+ K++
Fig.5 Drought and K effect on RWC of wheat
30

31. Effect on Chlorophyll Pigments
Treatments Chl a Chl b Chl (a+b)
Well-water-K 0.72±0.020c 0.38±0.012c 1.09±0.02d
Well-water+K 0.85±0.076ab 0.47±0.01b 1.32±0.08b
Well-water+2K 0.91±0.020a 0.52±0.04a 1.43±0.06a
50%FC-K 0.49±0.035e 0.25±0.03e 0.74±0.06f
50%FC+K 0.56±0.046d 0.36±0.04c 0.93±0.06e
50%FC+2K 0.79±0.020bc 0.40±0.04c 1.20±0.06c
20%FC-K 0.30±0.025f 0.18±0.02f 0.47±0.04g
20%FC+K 0.43±0.062e 0.29±0.03de 0.72±0.03f
20%FC+2K 0.61±0.035d 0.29±0.03d 0.90±0.05e
Treatments Chl a Chl b Chl (a+b)
Well-water-K 0.72±0.020c 0.38±0.012c 1.09±0.02d
Well-water+K 0.85±0.076ab 0.47±0.01b 1.32±0.08b
Well-water+2K 0.91±0.020a 0.52±0.04a 1.43±0.06a
50%FC-K 0.49±0.035e 0.25±0.03e 0.74±0.06f
50%FC+K 0.56±0.046d 0.36±0.04c 0.93±0.06e
50%FC+2K 0.79±0.020bc 0.40±0.04c 1.20±0.06c
20%FC-K 0.30±0.025f 0.18±0.02f 0.47±0.04g
20%FC+K 0.43±0.062e 0.29±0.03de 0.72±0.03f
20%FC+2K 0.61±0.035d 0.29±0.03d 0.90±0.05e
Mean (SD) was calculated from three replicates for each treatment. values with different
letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test
Table 2: Drought & K effect on leaf chlorophyll contents
31

32. Oxidative markers (MDA, H2O2) & MG
cd
b
a
e
d d
f
e
c
0
10
20
30
40
50
60
70
80
90
Well water 50% FC 20% FC
MDAcontent(nmolg-1freshweight)
K- K+ K++
c
b
a
d
c
b
e
cd
a
0
2
4
6
8
10
12
14
16
Well water 50% FC 20% FC
H2O2content(nmolg-1freshweight)
K- K+ K++
e
b
a
f
cd cd
f
de
be
0
5
10
15
20
25
30
35
Well water 50% FC 20% FC
MGcontent(nmolg-1freshweight)
K- K+ K++
Fig.6 Drought & K effect on MDA, H2O2, MG
32

33. Proline content
c
b
a
c
c c
d d
b
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Well water 50% FC 20% FC
Prolinecontent(µmolg-1freshweight)
K- K+ K++
Increased Proline protect plants during stress through stabilization of subcellular
structure to maintain ions homeostasis
Fig.7 Drought & K effect on Proline content
33

34. AsA-GSH cycle
H2O
H2O2
AsA
MDHA
NADH
NAD+
DHA
AsA GSSG
GSH NADP
+
NADPH
Fig. 8 Ascorbate-glutathione cycle regulates oxidative stress in plants
34

35. AsA-GSH cycle (Enzymes)
e
d
c
d
c
b
d
bc
a
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Well water 50% FC 20% FC
APXactivity(µmolmin-1mg-1protein)
K- K+ K++
Fig.9 Drought & K effect on APX activity 35

36. AsA-GSH cycle (Enzymes)
cd
ef
f
de
c
b
a
c
c
0
10
20
30
40
50
60
70
Well water 50% FC 20% FC
GRactivity(nmolmin-1mg-1protein)
K- K+ K++
Fig.10 Drought & K effect on GR activity 36

37. Drought reduced the catalase activity
cd
e
f
b
bc
de
a
bc
e
0
20
40
60
80
100
120
140
Well water 50% FC 20% FC
CATactivity(µmolmin-1mg-1protein)
K- K+ K++
Fig.11Drought & K effect on CAT activity 37

38. GPX Activity
bc
d
e
ab c
d
a
c
d
0
20
40
60
80
100
120
140
160
Well water 50% FC 20% FC
GPXactivity(µmolmin-1mg-1protein)
K- K+ K++
Fig.15 Drought & K effect on GPX activity
38

39. Root-shoot K content
Treatment(µmol/g) Root (µmol/g) Shoot(µmol/g)
Well-watered –K 165.99±6.35c 547.20±32.50b
Well-watered +K 240.70±27.00b 635.20±12.69a
Well-watered +2K 286.50±30.28a 644.60±17.39a
50%FC -K 159.33±11.68cd 466.40±35.73c
50%FC +K 164.95±29.70cd 562.80±30.42b
50%FC +2K 233.24±15.41b 586.95±51.82b
20%FC -K 128.09±21.92de 363.38±24.06e
20%FC +K 154.98±12.67cd 439.65±18.87cd
20%FC +2K 105.18±21.82e 395.72±26.61de
Treatment(µmol/g) Root (µmol/g) Shoot(µmol/g)
Well-watered –K 165.99±6.35c 547.20±32.50b
Well-watered +K 240.70±27.00b 635.20±12.69a
Well-watered +2K 286.50±30.28a 644.60±17.39a
50%FC -K 159.33±11.68cd 466.40±35.73c
50%FC +K 164.95±29.70cd 562.80±30.42b
50%FC +2K 233.24±15.41b 586.95±51.82b
20%FC -K 128.09±21.92de 363.38±24.06e
20%FC +K 154.98±12.67cd 439.65±18.87cd
20%FC +2K 105.18±21.82e 395.72±26.61de
Mean (SD) was calculated from three replicates for each treatment. values with different
letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test
Table 3: Root- Shoot mineral content (Potassium)
39

40. So, How K played in stress protection?
Exogenous K
Non enzymatic
antioxidants
Enzymatic
antioxidants
Glyoxalase
system
Methylglyoxal
ROS reduction
40

41. Conclusion

42. Conclusion
Wheat seedlings exposed to drought stress results in..
Reduced growth, chlorophyll pigments, RWC, ROS & MG production, disrupting
antioxidant defense and glyoxalase systems
Potassium treatment recovered..
plant growth by reducing ROS and MG production through up-regulating
antioxidant and glyoxalase systems, respectively
From (0mM, 6mM & 12mM) Potassium, 12 mM at 50% FC was observed to
provide best protection against drought
42

43. Recommendations
 Further study to know the molecular basis of how potassium uptake
while in drought stress
 Increase fertilizer management
 Recommend supplementary dose of potassium fertilizers in drought
prone areas of Bangladesh
43

44. Research Pictures
3 days after 1st nutrient supplySeedlings after germination
15 days of seedlings Before stress treatment 44

45. Acknowledgements

46. Acknowledgement

47. Acknowledgements
Laboratory of Plant Stress Responses

48. Acknowledgement
Professor, Dr. Mirza Hasanuzzaman
Department Of Agronomy
Sher-e-Bangla Agricultural University

51. Feed me to feed you…….
17th June
World day to combat desertification