plant molecular mechanism to drought and salt stress, and other stresses.

1. PLANT BIOTECHNOLOGY
BIOTIC & ABIOTIC STRESS
Guided By
Dr. Kishor Kumar
Presented By
Dushyant Kumar

2. Planthomeostasis
Metabolic processes can only take place in specific physical and
chemical environmental conditions.
The maintenance of a steady state results in a meta-stable condition
called homeostasis.

3. STRESS
Modulation of homeostasis
(Or)
External factors that adversely
affect the growth, development
and productivity.
• Stresses trigger a wide range of plant
responses:
altered gene expression
cellular metabolism
changes in growth rates and crop yields

4. Stress
Biotic
weeds
Pathogens
Insects
Abiotic
Water
Temperature
Salt/Ions
Air Pollution
Others

5. Stress
Stress
response
Susceptible
Senescence
Death
No effect
avoidance Survival
Resistance
Assimilation
Growth
Survival

6. AbioticStress
• Water
Excess- plant cell swell and burst.
Drought- plant drying called desiccation.
• Temperature
High- plant cell proteins denaturation, enzymatic activity
imbalance.
Low- chilling stress : affect the rate & amount of water & nutrient
uptake
• Salts/ Ions
Toxicity
Deficiency
• Air pollution
• Radiation

8. 1. Signaling during excess salt

9. 2. Cold & Drought stress

10. PYL- pyrabactin resistance
family molecule: acceptor of
ABA
PP2C- protein phosphatase 2
SnRK2- serine threonine like
kinases family
SLAC 1- slow anion channels
NF Y- nuclear factor Y

11. Genes involved in responses

12. Proteins and hormones in response to stress

13. Bioticstresses
Damages caused by living organisms like
• Weeds- compete with plant for food, water, minerals & space.
• Pathogens- causes diseases to plants
Bacterial pathogens
Fungal pathogens
Viral pathogens
• Insects- cause damage to leaves, stem, fruit, root
• Herbivores animals

14. Pathogen Strategies
1. Necrotrophic – plant tissue killed and then colonized;
1. broad host range
2. Bacteria and fungus
2. Biotrophic – plant cells remain alive
1. narrow host range (1 plant species)
2. viruses, fungus

15. Plant Defense
1. Physical barriers:
1. cuticle
2. thorns
3. cell walls
2. Constitutively produced chemicals
1. phytoalexins
2. proteins (e.g., Ricin)
3. Induced responses (the Plant Defense Response)

16. Induced responses
Plant reaction to invading pathogens- role of
hypersensitive reaction.
• Hypersensitive reaction initiates many changes in plant physiology
and biochemistry.
• Early activation of defense related genes to synthesis pathogenesis
related proteins
• Protease inhibitors to stop cell wall lysis by specific enzymes
expressed by pathogens.
• Bacterial cell wall lytic enzymes (chitinase, glucanase).
• Change cell wall composition.
• Express enzymes providing structural support to cell walls via
synthesis of lignin, suberin, callose, glycoproteins.
• Syntheises secondary metabolites to isolate and limit the pathogen
spread.
• E.g.. – iso-flavonoids, phytoatexins