It contains data about secondary metabolites and how they help to combat plant under stress.

1. SECONDARY METABOLITES
AND ABIOTIC STRESS
Presented by : Areej Fatima
Enrolment no : MphillBot-09F23
Presented to : Dr. Asma Zulfiqar
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2. TABLE OF CONTENTS
 Introduction of Secondary metabolites
 Why and How plants produce them?
 Classes of secondary metabolites
 Implications
 Abiotic stress
 Factors and their effects
 Role in Plant Physiology
 Conclusion
 Reference
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3. SECONDARY METABOLITES
Secondary metabolites (SMs) are compounds produced by plants
through subsidiary pathways that are not directly involved in basic
plant life functions. This means that they are not essential for the
plant. However, they mediate plant-environment interactions and
might be crucial for its survival and reproduction. Secondary
metabolites are often species-specific and exert a wide range of
effects on the plant itself and other living organisms.
Their functionality was first related to their effect on human health
and many years later, they became the focus of plant science for
commercial and academic research purposes. At present, secondary
metabolites are a constant in our lives. As an example, we
have caffeine, a plant secondary metabolite found in coffee, tea, or
chocolate, which not only helps us start the day on the right foot but
is also a therapeutic tool against degenerative diseases!
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4. WHY AND HOW DO PLANTS PRODUCE THEM?
First, plants, unlike animals, are sessile organisms that cannot move
when facing biotic or abiotic stress. Therefore, they need to adapt to
survive, and secondary metabolites were the response. These chemicals,
although being generated in little quantities at a significant energy cost,
govern the plant's defensive system. They are also in charge of the
plant’s response to changing environmental circumstances.
To produce them, plants use by-products or intermediates of primary
metabolism as the basis of most of the secondary metabolites. They tend
to be synthesized in specialized cell types, in selected plant life stages.
The different reactions and pathways that plants use to produce SMs are
called the plant secondary metabolism. This metabolism is only
activated under certain periods and conditions, with stress signals being
the ones that trigger it.
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5. CLASSES OF SECONDARY METABOLITES
A single plant can produce hundreds of secondary
metabolites under appropriate conditions and stimulation.
Each secondary metabolite differs from the others in its
chemical structure and bioactivity. The main classes of
secondary metabolites are:
 Phenolic : such as salicylic acid (used in the cosmetic
industry) and flavonoids (known as pigments);
 Alkaloids: such as nicotine (from tobacco plants),
morphine (from poppy straw); and
 Terpenes : such as menthol and limonene.
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6. IMPLICATIONS OF SECONDARY METABOLITES
In natural systems, secondary metabolites make plants competitive in
their own environment. The ecological implications and functions of
SMs are:
 Induce flowering, fruit set, and abscission;
 Maintain perennial growth;
 Signal deciduous behavior;
 Attracting or repelling other organisms;
 Defense against herbivores, fungi, bacteria, viruses, and other
plants;
 Signaling to attract pollinating and seed dispersing animals;
 Plant to plant communication.
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7. ABIOTIC STRESS
Abiotic stress is defined as the negative impact of non-living
factors on living organisms in a specific environment. The
stresses include d
 Drought
 Salinity
 Low or high temperatures, and
 Other environmental extremes.
Abiotic stresses, especially salinity and drought, are the
primary causes of crop loss worldwide
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8. Figure 1. Abiotic stress reduces crop yield. Environmental stress factors, such as heat, cold,
drought, salinity, and the presence of heavy metals such cadmium, copper, and chromium, elicit
stress responses in plants, including an accumulation of reactive oxygen species (ROS) and
reduced photosynthetic activity, which ultimately lower plant growth and thus crop yields
©: https://www.mdpi.com/
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9. HEAT STRESS
©: Journal of Plant Growth Regulation
9

10. DROUGHT STRESS
©: https://link.springer.com/book/10.1007/978-981-16-7981-0
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11. SALINITY
©: Encyclopedia of Plant Environment.
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12. ROLE OF SECONDARY METABOLITES
UNDER SALINITY
Fig : Growth of pea harvested at 58 DAS under the treatments of
Glutathione (A secondary metabolite) and Salt stress.
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13. EFFECT ON ROOT
Fig : Effect of Glutathione and NaF on Pea Root
©: Fatima, A et al (2022)
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14. EFFECT ON SHOOT
Fig : Effect of Glutathione and NaF on Pea Root
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15. a
ab
ab
b
ab
a
ab a
0
200
400
600
800
1000
1200
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Photosynthetic
rate
(μ
mol
m-2
s-1)
Treatments
PHOTOSYNTHETIC RATE
15

16. b d
c
a
c
b
b
c
0
0.05
0.1
0.15
0.2
0.25
0.3
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Traspiration
rate
(mmol
H2O
m-2
s-1)
Treatments
TRANSPIRATION RATE
16

17. CHLOROPHYLL a
a b
c
e
e
c
d
c
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Chlorophyll
a
(mg
g-1
FW)
Traetments
17

18. c b
e
e
d
a
c
b
0
0.02
0.04
0.06
0.08
0.1
0.12
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Chlorophyll
b
(mg
g-1
FW)
Treatments
CHLOROPHYLL b
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19. c
a
f
e d
a
c
a
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Total
chlorophyll
(mg
g-1
FW)
Treatments
TOTAL CHLOROPHYLL
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20. CAROTENIODS
b
a
d
e
e
d
c
c
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Caroteniods
(mg
g-1
FW)
Treatments
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21. PROLINE CURVE
y = 0.214
R² = 0.9894
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.5 1 1.5 2 2.5 3
Absorbance
(520nm)
Proline Concentration (µmol/g)
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22. PROLINE GRAPH
d
a
d
g
b
c
f
e
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Control NaF Glu 1 Glu 2 Glu 3 Glu 1 +
NaF
Glu 2 +
NaF
Glu 3 +
NaF
Proline
content
(μmolg-1
FW)
Treatments
22

23. Effect of Glu and NaF on Chlorophyll a content of pea.
Data exhibit means ±SD of 3 replicates. Non-identical letters specify
significant
dissimilarity between the treatments (P ≤ 0.05).C= un contaminated
Control, NaF =
contaminated Control (100 mL NaF), Glu 1 = 25 μM Glutathione,
Glu2 = 50 μM
Glutathione, Glu 3 = 75 μM Glutathione, Glu 1 + NaF= 25 μM Glu +
100 mL NaF,
Glu 2 + NaF= 50 μM Glu + 100 mL NaF, Glu 3 + NaF= 75 μM Glu
+ 100 mL NaF.
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24. CONCLUSION
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25. REFERANCES
 Alvarez, M. A. (2014). Chapter 3 - Plant Secondary Metabolism. Plant Biotechnology for Health, 15–
31. doi:10.1007/978-3-319-05771-2_3
 Böttger, A., Vothknecht, U., Bolle, C., & Wolf, A. (2018). Plant Secondary Metabolites and Their
General Function in Plants. Learning Materials in Biosciences, 3–17. doi:10.1007/978-3-319-99546-
5_1
 Clemensen, A. K., Provenza, F. D., Hendrickson, J. R., & Grusak, M. A. (2020). Ecological Implications
of Plant Secondary Metabolites - Phytochemical Diversity Can Enhance Agricultural
Sustainability. Frontiers in Sustainable Food Systems, 4. https://doi.org/10.3389/fsufs.2020.547826
 Erb, M., & Kliebenstein, D. J. (2020) Plant Secondary Metabolites as Defenses, Regulators, and
Primary Metabolites: The Blurred Functional Trichotomy. Plant Physiology, 184(1):39–
52. https://doi.org/10.1104/pp.20.00433
 Guerriero, G., Berni, R., Muñoz, J. A., Apone, F., Abdel, E. M., Qahtan, A. A., Alatar, A. A., Cantini, C.,
Cai, G., Hausman, J. F., Siddiqui, K. S., Hernández, S. M. T., & Faisal, M. (2018). Production of Plant
Secondary Metabolites: Examples, Tips and Suggestions for Biotechnologists. Genes,
9(6):309. https://doi.org/10.3390/genes9060309
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26.  Hussein, R. A., & El-Anssary, A. A. (2018). Plants Secondary Metabolites: The Key Drivers of
the Pharmacological Actions of Medicinal Plants. In (Ed.), Herbal Medicine.
IntechOpen. https://doi.org/10.5772/intechopen.76139
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