molecular responses of plants to abiotic stresses and applied molecular biology for crop improvement under abiotic stresses.

1. Welcome
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2. Molecular response of plants to
Abiotic Stresses
A.DINESH
Jr. M.Sc(Agri)
PG13AGR5055
Dept: Genetics and plant breeding
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Seminar-I

3. Content
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INTRODUCITON
TERMINOLOGIES
SIGNALING PATHWAYS
GENE EXPRESSION TO STRESS CONDITION
PROLINE SYNTHESIS
CASE STUDIES
CONCLUSIONS

4. Losses caused by the Abiotic stress
• The progressive salinization of soil, estimated at around 20 %
of irrigated land in world (Ghassemi et al.,1995)
• High temperature coupled with drought during pollination
period of maize plants can result in up to 100 % yield loss
(Heiniger et al., 2001)
• It was estimated that approximately 70 % of yield reduction
was due to abiotic stress ( Acquaah, 2007)
• The estimated potential yield losses are 17 % due to drought,
20 % due to salinity, 40 % due to high temperature, 15 % due
to low temperature and 8 % due to other stress
( Ashraf et al., 2008)
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5. STRESS
ABIOTIC
WATER
DEFICIT
EXCESS
TEMPERATURE
HIGH
LOW
SALT/ION
TOXICITY
DIFFICIENCY
AIR
POLLUTION
OTHERS
BIOTIC
Plant stress
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6. Heat stress
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8. Water depletion :
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Water stress :

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Lobell et al., 2011

11. Terminology:
• Heat stress : A transient elevation in temperature, usually 10-
15°C above ambient, is considered heat shock or heat stress
(Wahid et al., 2007)
• Low-temperature stress : Chilling (<20°C) or freezing (<0°C)
temperatures can induce ice formation in plant tissues,
leading to cellular dehydration (chinnusamy et al., 2007)
• Water stress: The condition where a plant’s water potential
and turgor are decreased enough to inhibit normal plant
function (Hsiao et al., 1973)
• Oxidative stress : It is an imbalance between the production
of ROS and their scavenging
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Cramer et al., 2011

13. How plants respond to environmental
stress ?
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14. Stress resistance mechanisms
1. Avoidance mechanisms
 prevents exposure to stress
2. Tolerance mechanisms
 permit the plant to withstand stress
3. Acclimation
 alter their physiology in response stress
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15. Plants molecular mechanisms in
response to stress involve:
 Activation of signaling pathways
 Production of ROS
 Activation of transcription factors
 Alter gene expression
 Breakdown of macro molecules
 Decrease in protein synthesis
 Synthesis of osmolytes
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16. General Stress Signal Transduction
Pathway
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(Xiong and Zhu, 2001)

17. Abscisic acid (ABA) synthesis :
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1.Zeaxanthin epoxidase (ZEP,)
2. 9-cis-epoxycarotenoid
dioxygenase (NCED).
3.ABA-aldehyde oxidase (AAO)
4.Molybdenum
cofactor sulfurase (MCSU)

18. ABA Signal transduction :
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Danquah et al., 2013

19. Stomatal closure under stress :
19Qin et al., 2011

20. Mitogen Activated Protein Kinase
(MAPK) :
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Danquah et al., 2013
Fig. 2. A typical MAPK cascade.

21. ROS production
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22. Oxidative stress
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23. ROS signal transduction
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Fig. 1.Three stages are proposed to exist in this signal transduction
Miller et al., 2008

24. Cold stress :
24Qin et al., 2011

25. Osmotic stress
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26. Gene expression to osmotic stress :
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Shinozak et al.,1997

28. Heat stress
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Hasanuzzaman et al., 2013

29. Genes linked to more than one abiotic stresses
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Ahuja et al., 2010

30. Osmolyte : Proline
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Szabados and Savoure, 2009

31. Functions of Proline :
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32. Glycinebetine:
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33. Materials and Method : Wheat , Tobacco
• PEG6000
• NaCl solutions
• H2O2
• Total RNA : TRIzol reagent
• Objective : To know whether WRKYs confer drought
and salt stress tolerance
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Wang et al., 2013

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Daun and Cai, 2012
Plant materials and methods :
Rice cultivar ZH11 used in transformation, Arabidopsis thaliana
Vectors : pYES2, pHB
Objective :
To identify the role of osLEA3-2 in salt and drought tolerance

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Figure 4. Growth of S. cerevisiae cells expressing OsLEA3-2 and the control cell in
the medium containing 1.2 M NaCl (A), 1.2 M KCl,(B), and 2.0 M sorbitol (C).

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47. Method and Treatments :
Upland cotton (Gossypium hirsutum L.) C312
1. ABA
2. Salinity stress : NaCl
3. Cold : 4°C
4. Drought stress : Mannitol.
5. Alkalinity stress : pH 11,
Objectives:
1. Transcriptome profiling of cotton seedlings stressed with
ABA, cold, drought, salinity and alkalinity .
2. Differentially expressed genes and related crosstalk
network for stress perception, signal transduction
47Zhu et al., 2013

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50. Cross talk among stress genes
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51.  Among the 64 induced and 62 repressed genes.
Only 29 induced and 30 repressed genes have
characterized in cotton and shown homology with
Rice
 13 of 29 commonly induced and 11 from the 30
commonly repressed transcripts took roles in signal
transduction and regulation of gene expression
under abiotic stresses
 ABA signal transduction components, PP2C 77
and PP2C 12, were up-regulated
 The genes DELLA protein RGA,4-coumarate--
CoA ligase-like 7 and putative 12-oxophytodienoate
reductase and HSP20, HSP70 were repressed
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Yamamoto and Momonoki, 2012
Objective :
1. Role of acetylcholinesterase enzyme (AChE) to
heat stress
2. Tissue localization of maize acetylcholinesterase
enzyme.

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