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Welcome
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Molecular response of plants to Abiotic Stresses
A.DINESHJr. M.Sc(Agri) PG13AGR5055
Dept: Genetics and plant breeding
Seminar-I
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Content INTRODUCITON
TERMINOLOGIES
SIGNALING PATHWAYS
GENE EXPRESSION TO STRESS CONDITION
PROLINE SYNTHESIS
CASE STUDIES
CONCLUSIONS
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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STRESS
ABIOTIC
WATER
DEFICIT
EXCESS
TEMPERATURE
HIGH
LOW
SALT/ION
TOXICITY
DIFFICIENCYAIR
POLLUTION
OTHERS
BIOTIC
Plant stress
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Heat stress
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Water depletion :
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Water stress :
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Lobell et al., 2011
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 11
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Cramer et al., 2011
How plants respond to environmental stress ?
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Stress resistance mechanisms 1. Avoidance mechanisms
prevents exposure to stress2. Tolerance mechanisms
permit the plant to withstand stress3. Acclimation
alter their physiology in response stress
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Plants molecular mechanisms in response to stress involve:
Activation of signaling pathwaysProduction of ROSActivation of transcription factorsAlter gene expressionBreakdown of macro moleculesDecrease in protein synthesisSynthesis of osmolytes
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General Stress Signal Transduction Pathway
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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)
ABA Signal transduction :
18Danquah et al., 2013
Stomatal closure under stress :
19Qin et al., 2011
Mitogen Activated Protein Kinase (MAPK) :
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Danquah et al., 2013Fig. 2. A typical MAPK cascade.
ROS production
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Oxidative stress
ROS signal transduction
23Fig. 1.Three stages are proposed to exist in this signal transduction
Miller et al., 2008
Cold stress :
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Osmotic stress
Gene expression to osmotic stress :
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27Shinozak et al.,1997
Heat stress
28Hasanuzzaman et al., 2013
Genes linked to more than one abiotic stresses
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Ahuja et al., 2010
Osmolyte : Proline
30Szabados and Savoure, 2009
Functions of Proline :
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Glycinebetine:
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Materials and Method : Wheat , Tobacco• PEG6000• NaCl solutions• H2O2• Total RNA : TRIzol reagent • Objective : To know whether WRKYs confer drought
and salt stress tolerance
Wang et al., 2013
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40Daun and Cai, 2012
Plant materials and methods :Rice cultivar ZH11 used in transformation, Arabidopsis thalianaVectors : 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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Method and Treatments : Upland cotton (Gossypium hirsutum L.) C312 1. ABA 2. Salinity stress : NaCl3. Cold : 4°C4. Drought stress : Mannitol.5. Alkalinity stress : pH 11,Objectives: 6. Transcriptome profiling of cotton seedlings stressed with ABA, cold,
drought, salinity and alkalinity . 7. Differentially expressed genes and related crosstalk network for
stress perception, signal transduction
Zhu et al., 2013
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Cross talk among stress genes
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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 stress2. Tissue localization of maize acetylcholinesterase
enzyme.
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Thank you…..