Abiotic stresses, especially cold, salinity and drought, are the primary causes of crop loss worldwide. Plant adaptation to environmental stresses is dependent upon the activation of cascades of molecular networks involved in stress perception, signal transduction, and the expression of specific stress-related genes and metabolites. Plants have stress-specific adaptive responses as well as responses which protect the plants from more than one environmental stress. There are multiple stress perception and signaling pathways, some of which are specific, but others may cross-talk at various steps (Knight & knight ,2001).Many cold induced pathways are activated to protect plants from deleterious effects of cold stress, but till date, most studied pathway is ICE-CBF-COR signaling pathway (Miura and Furumoto,2013 ) . The Salt-Overly-Sensitive (SOS) pathway, identified through isolation and study of the sos1, sos2, and sos3 mutants, is essential for maintaining favorable ion ratios in the cytoplasm and for tolerance of salt stress (shi .et al ,2002). Both ABA-dependent and -independent signaling pathways appear to be involved in osmotic stress tolerance (Nakashima and shinozaki, 2013) .ROS play a dual role in the response of plants to abiotic stresses functioning as toxic by-products of stress metabolism, as well as important signal transduction molecules and the ROS signaling networks can control growth, development, and stress response ( Mahajan,s and Tuteja, 2005) .

1. Drought
salt
Heat
Cold
Cellular Signal
Transduction Pathways
under abiotic stress in
plants & its applications
Chavan Neha

2. Securing food with less land
13 billion hectares (Earth’s surface)
1.5 billion 3.5 billion hectares
( agriculture) (meadowland pasture.)
seven million hectares of agricultural
land are lost (every year)
Need of four billion hectares of land.
As a result of population growth, agricultural production must increase
by around two percent per year . (FAO statistical division ,2008)

3. What is stress???
‘’A biological stress is an adverse force or a
condition, which inhibits the normal
functioning and well being of a biological
system such as plants .’’
(jones et.al ,1989)

4. Stress elicitors
• cell response is initiated by
interation of extracellular
material with plasma membrane
protein.
• The extracellular molecule is
called as ligand and the protein
with which it will interact is
called as receptor.
Abiotic
1. Cold (chilling and frost)
2. Heat (high temperature)
3. Salinity (salt)
4. Drought (water deWcit condition)
5. Excess water (Xooding)
6. Radiations (high intensity of ultra-
violet and visible light)
7. Chemicals and pollutants (heavy
metals, pesticides, and aerosols)
8. Oxidative stress (reactive oxygen
species, ozone)
9. Wind (sand and dust particles in
wind)
10. Nutrient deprivation in soil
Biotic
1. Pathogens (viruses, bacteria, and
fungi)
2. Insects
3. Herbivores
4. Rodents
(Mahajan & Tuteja, 2005)

5. Major cause of loss in Crop production
stress
•Stress reduces harvests
dramatically
•Abiotic factors are
responsible for the lion’s
share of harvest losses,
however.
(Bayers crop science magazine,2008)

6. How abiotic stress affects the growth and development of crop
(Vicers et.al ,2009)

7. Biotechnological approches to study stress response in plants
(Climente et.al,2013)

8. Overview of signal transduction pathway
(Mahajan & Tuteja, 2005)

9. Crosstalk of signal transduction pathways
(Knight & knight ,2001)

10. Complexity
(Wangxia Wang et al.,2003)

11. Types of signal transduction
pathways
Ionic &Osmotic
stress signaling
Signaling to co-
ordinate cell division
& expansion
Signaling for
detoxification .
(Jian –kang Zhu ,2011)
Cellular Homeostatis Control and repair cell
damage due to stress
To level suitable stress
condition

12. (Miransari et al ,2013)
Contd..,

13. Major signal transduction pathways under
abiotic stress(drought ,salt and osmotic stress )
• ABA (dependent and independent)signaling
• MAPK mediated signaling
• SOS signaling
• Phospholipid signaling.

14. ABA biosynthesis
(Zhu et al ,2005)
Pyrophosphate +glyceraldehyde
3 phosphate
IPP(isopentenyl pyrophosphate)
Farnesyl pyrophosphate,GGPP,B-carotein
Beta carotein
Zeaxanthin
ZEP
Violaxanthin
NCED
Neoxanthin
Xanthoxin
ABA aldehyde
Xanthoxinic
acidABA
Phaseic acid
Abscisic
alcohol

15. ABA conjugation
• ABA can be inactivated at C1 ,by forming different conjugate .
• One of this conjugate is ABA –GE
• Over-expression of UGT71B6 leads to an increased ABA-GE content in
Arabidopsis.
The incresed ABA-GE will be stored in vacuoles.
• What happens is that under dehydration condition the GE gets separated
out from ABA by the enzyme Betaglucosidase(BG)
‘’Recently 2 BG ,BG1 and BG2 identified in Arabidopsis’’
(Danquah et al , 2013)
Free ABA

16. ABA Transport :
Two main transporters of ABA – 1.AtABCG25 2.AtABCG40
‘’ The stomata of atabcg40mutants close more slowly in response to
ABA, resulting in reduced drought tolerance.’’
(Danquah et al , 2013)

17. Early events in ABA signaling
(Nakashima & shinozaki ,2013)
Identification of SnRK2

18. ABA dependent and Independent pathway

19. Mitogen activated protein kinase pathway
(Danquah et al , 2013)

20. Recent updates
• ZmMkk1-Chilling stress & pathogen defence
(Cai et al ,2013 )
• ZmMkk3- mediates osmotic stress and gives
signal for ABA (Cai et al ,2013 )
• ZmMpk5-salt stress in maize (Zang et al
,2013)
• MAPK3 – confers U.V and Heat tolerance
(Raina et al ,2013 )

21. (Danquah et al , 2013)
ABA induced activation of MAPK
ABA perception in guard cell
activate SnRK2 kinase (OST 1)
Phosphoraylation of NADPH oxidase Rhof
Leads to ROS accumilation
Activate 2 MAPKs,MPK9/12
SLAC activation
Stomal opening
SLAC-s type ionic channel
PYR-
Enhanced transpiartional loss

22. SOS pathway under salt stress
(Mahajan & Tuteja ,2005)

23. Osmotic stress, cold, and ABA activate several types of
phospholipases that cleave phospholipids to generate
lipid messengers (e.g., PA, DAG, and IP3), which
regulate stress tolerance partly through modulation of
gene expression. FRY1 (a 1-phosphatase) and 5-
phosphatase-mediated IP3 degradation attenuates
the stress gene regulation by helping to control
cellular IP3 levels.
Phospholipid signaling
(jian-kang Zhu ,2002)

24. PLD and PA in response to H2O2
PLD , is activated in response to H2O2 and the resulting PA functions in amplification of
H2O2 -promoting antiPCD
Stress stimulates production of H2O2 that activates PLD associated with the plasma
membrane. Potential activators: Ca2+ and oleic acid. This increases PLD affinity to its
substrates, stimulating lipid hydrolysis and PA production. PA may bind to target
proteins, such as Raf-like MAPKK, that contain a PA binding moti, leading to the .)
activation of MAPK cascades. PA may also function by modulating membrane
trafficking and remodeling. These interactions modulate the cell's ability to respond to
oxidative stress and decrease cell death. Dashed lines - hypothetical interactions.

25. •Knockout of PLD renders Arabidopsis plants more
sensitive to the reactive oxygen species H2O2 and to
stresses
•H2O2 activates PLD , and PLD -derived PA functions to
decrease the promotion of cell death by H2O2. These
results suggest that both PLD and its product PA play
a positive role in signaling stress responses
•PLD and its derivative PA provide a link between
phospholipid signaling and H2O2-promoted cell death.
PLD and PA positively regulate plant cell survival and
stress responses.
PLD and PA
(Laxalt and Munnik,2002)

26. Transcriptional regulatory network under abiotic stress responses
(Hirayama & shinozaki ,2010)

27. Signaling under heat stress
(Bokszczanin & fragcostefanakis ,2013)

28. Signaling under cold stress
Cold stress signaling with secondary messenger
Plants may sense low temperature through changes in the physical properties of
membranes, because membrane fluidity is reduced during cold stress
plasma membrane rigidification raised by a membrane rigidifier, dimethyl sulfoxide
(DMSO),
Induction of COR gene
Second shock
Increase in ca+ Regulation of COR gene expression
Ca sensors
CBF
calmodulin
CDPKs
CCaSK
Positive regulation of
cold stress Negative regulation of
cold stresss
CAMAT
Miura and Furumoto,2013

29. CBF dependent signaling
Miura and Furumoto,2013
ICE1

30. Applications

31. Case study 1

32. Experimental protocol and results
1.Overexperssion of SOS1 in transgenic plants:
A. A.thaliana plants were transformed with a construct containing the SOS1 cDNA driven
by the cauliflower mosaic virus (CaMV) 35S promoter.
B. Screening is done on M.S. agar medium cantaining 40mh/l kanamycin.
C. Presence confirmed by PCR (primer specific for 35s promoter and SOS1gene )
2.RNA gel Blot:
A. A.Thaliana plant grown on M.S.medium under continous light.
B. For salt treatment
10 days old seeding
Whatman filter paper
soaked with 100mM Nacl
&200 mM Nacl
Whatman filter paper
soaked in M.S. medium
(stress) (Control)
Total RNA isolation and Nouthern analysis

33. Control
transgenic
Stress given
0mM,1oomM,200mM
Resisitant lines (ST-4,ST-8) analysised for RNA gel Blot

34. Same lines S-4 ,S-8 grown on medium (M.S),cantaning different conc. of
Nacl
Physiological analysis of plants
Root growth
Chlorophyll
content
Total protein level

36. figure 4. :Reduced Na+ accumulation in plants overexpressing SOS1.
control ST -8 ST-4

37. Figure 3. Enchanced salt tolerance of SOS1-overexpressing plants
Control 50 mM 150mM

38. Figure 5. Calli overexpressing SOS1 are more tolerant of NaCl.

39. Case study 2

40. Results
High expresssion was found in P58 and P1142

41. Fig. 2 Growth characteristics of the AtDREB1A plants and the cultivar BR16 under control (C-dark
bars) and moderate water stress (DS-grey bars) conditions in the greenhouse. Differences were
not statistically significant (Duncan 5 %) (n = 6)

42. Transpiration of Atderb1A plants an cultivator BR16 ,A - water stress ,B-in
greenhouse
Green
house
phytotron

43. Conclusion
• Abiotic stress signaling is an important area with
respect to increase in plant productivity. Therefore,
the basic understanding of the mechanisms underlying
the functioning of stress genes is important for the
development of transgenic plants. Each stress is a
multigenic trait and therefore their manipulation may
result in alteration of a large number of genes as well
as their products. A deeper understanding of the
transcription factors regulating these genes, the
products of the major stress responsive genes and
cross talk between different signaling components
should remain an area of intense research activity in
future.

44. Discussion

45. References
• Knight,H.and knight,M.R.2001.Abiotic stress signaling
pathways:specificity and crosstalk.Trends in Plant sci.,6:262-267
• Zhu,J.K.2002.Salt and Drought stress signal transduction in
plants.Ann.Rev.Plant Biology,53:247-273.
• Danguah,A.,Zelicourt,A.,colcombet,J.and Hirt,H.2013.The role of
ABA and MAPK signaling pathways in Plant abiotic stress
response.Biotechnological Adv.,
• Hirayama,T and Shinozaki,k.2010.Research on Plant abiotic stress
response in post genome era:past,present& future.The Plant
journal,61:1041-1052
• Mahajan,s and Tuteja,N.2005.cold,salinity & drought stress:An
overview .Archi.Biochem.biophysics,444:139-158

46. References
• Miura,k and Furumoto,T.2013. Cold Signaling and Cold Response in
Plants.Int.J.Mol.Sci.,14:5313-5337.
• Shinha,A.k.,Jaggi,M.,Raghuram,B.and Tuteja,N.2011.Mitogen
activated protein kinase signaling in plants under abiotic stress.Plant
signaling and behaviour,6:196-203
• Nakashima,K.and shinozaki,K.Y.2013.ABA signaling in stress response
& seed development.Plant cell Rep,32:959-970
• Shi,H.,Lee,B.Wu,S.and Zhu,J.2002.Overexpression of plasma
membrane Na+/H+ antipoeter gene improves salt tolerance in
arabidopsis .Nature Biotechnology,21
• Bokszczanin ,K.L., and Fragkostefanakis ,S.2013.Perspectives on
deciphering mechanisms underlying plant heat stress response and
thermotolerance.Frontiers in Plant Sci.,4:135

47. Thank you…..