Secondary metabolites are organic compounds produced by plants that are not directly involved in their normal growth, development or reproduction but play an important role in plant defense. They are classified into terpenes, phenolic compounds and nitrogen-containing compounds. Plants have developed various defense mechanisms including chemical defenses using secondary metabolites that can deter herbivores and pathogens. Secondary metabolites also help improve disease resistance and shelf life of plants. They have applications in pharmaceuticals, pesticides, drug development and regulating plant metabolic processes.

1. ROLE OF SECONDARY METABOLITES IN PLANT DEFENSE
MECHANISM
Submitted To
The Principal
Mahatma Gandhi mission
College of Agricultural Biotechnology,
Aurangabad
Affiliated to Vasantrao Naik Marathwada
Krishi Vidyapeeth, Parbhani
( ISO 9001:2008 Certified)
Submitted by
Shinde Devidas Raghu
Registration no-
MGM/CABT/2011/65
Semester-VII (new) CS-4713
Seminar guide
Asst. professor -
V.D.DESHMUKH
Department of Plant

2. Sr.No Content Slide No.
1 Introducttion 3
2 Types of metabolites 3
3 Classification of sec.metaboolites 5
4 Resistance 6
5 Types of Resistance 6
6 Defense mechanism 9
7 Role of Sec.Metabolism 16
8 Applications 17
Index

3. ROLE OF SECONDARY
METABOLITES IN PLANT
DEFENSE MECHANISM
INTRODUCTION
Plants synthesize a vast range of organic compounds
that are traditionally classified as primary and
secondary metabolites.
Primary metabolites
compounds that have essential roles associated with
photosynthesis, respiration, and growth and development
Examples :- Phytosterols, acyl lipids, nucleotides, amino acids

4. Secondary metabolites
 organic molecules that are not involved in the normal
growth and development of an plant.
 Absence of it does not result in immediate death, but in
long-term impairment of the organism’s survivability,
often playing an important role in plant defense.
 Most of secondary metabolites, such as terpenes,
phenolic compounds and alkaloids are classified based on
their biosynthetic origin.
 Do not have generally recognised roles in the
photosynthesis, respiration, solute transport, translocation,
nutrient assimilation and differentiation.
 major role in the adaptation of plants to the changing
environment and in overcoming stress constraints.
Examples;-solasodine,alkaloid,glycoalkoloide, Anthocynin,
Flavonoids, Solanin, Alanine,Tomatidine,etc

5. Classification of secondary metabolites
1. Terpens
2. Phenollic compound
3. Nitrogen containing compound

6. Resistance
Ability or capability of plant to prevent itself from foreign
invading pathogen .
Types of Resistance
Two types of resistance.
1. Horizontal resistance
2. Vertical resistance
Horizontal resistance
 All plants have certain but not always the same level of
possibly unspecific resistance that is effective each of
their pathogen such resistance is called as Horizontal
resistance or it also called partial/polygenic/Quntitative
 Probably controlled by several genes therefore the name

7. limited number of genes, usually less than 4 to 5 are
most effective to resistance.
 Several genes involved in partial resistance seems to exit
their influence by controlling the numerous steps of
physiological process in the plant that provide material
and structure that makes up the defense mechanism.
Many cases one of these genes alone may be
ineffective against the pathogen and play minor
role in total horizontal resistance(minor gene
resistance)

8. Vertical resistance
Race specific resistance is always controlled by one or
few genes.so called as Monogenic. Oligogenic resistance
Race specific resistance inhibits the initial establishment
of pathogen.
Complete resistance may be provided by single gene and
it provide a resistance.
Ex- Wheat has 20 to 40 genes for resistance against
leaf rust fungus puccnia recondite.
Also referred as Monogenic/R-gene resistance/race
specific resistance.
Host and pathogen appears incompatible.
Host responds with hypersensitive reaction may appear
immune or inhibit pathogen reproduction.

9. Defense
The ability or capability to fight against the invading
pathogens
Mechanism of Defense
two kinds of defense mechanism viz.
1. Active mechanism of defense.
2. Passive mechanism of defense .
1. Chemical defense
Defense response in plants can be induced by physical
presence of fungal spore, pathogen, penetration,
nonspecific elicitors.
Qualitative metabolites are a toxins that interfere the
Geranium produces chemical compound in its petals to

10. It produces the chemicals within 30 minutes of ingestion
the paralyzes the herbivore plants have evolved many
secondary metabolites involved in plant.
1. Local signal
It is first response activated before induction of expression
and protein synthesis.
Example:-Ion fluxes, reactive oxygen species(ROS)
production photophosphorylation on cascade.
2. Cytoskeleton
Defense the attack of potential pathogen prior to
penetration.
plant defense protein as osmotin and chitinase are
associated with cytoskeleton.

11. 2.Mechanical defenses
 The Thorns on the stem of raspberry plant, serves as a
mechanical defense against the herbivory.
 plant structural defenses on stems and leaves can deter,
injure, or kill the grazer.
 Some defensive compounds are produced internally but
are released onto the plants surface.
 Ex- resins, lignins, silica, and wax cover the epidermis of
terrestrial plants
 Very smooth and slippery structure making feeding
difficult.
 Some plants produces gummosis or sap that traps
insects.

12. 1.Thigmonasty
movement of plant that occur in response to touch, are
used as a defense in
some plant.
The leaves of sensitive plant close up rapidly in response
to direct touch, vibration, or even electrical and thermal
stimuli.
Ex-Mimosa pudica
2. Leaf shedding and colour
Leaf shedding may be a response that provides
protection against disease and pest such as leaf miners
and gall forming insects.
change of leaf color prior to fall of pathogen.
 plants leaves stem may be covered with sharp prickles,
spines, thorns, or trichomes hairs on the leaf often with
barbs, sometimes containing irritants or poisons.

13. .
 plant structural features like spines and thorns reduce
feeding
 Branching and leaf arrangement may also to reduce
herbivore impact.
 In coconut and other palms, may protect their fruit by
layers of amours special skills to climb the tall and
relatively smooth trunk.

14. Plant disease resistance
Plant protects by two ways viz. by preformed mechanisms
and by infection-induced responses of the immune system
Disease resistance is the reduction of pathogen growth on
or in the plant
disease resistance describes plants that exhibit little disease
damage despite substantial pathogen levels.
Plant disease resistance is crucial to the reliable
production of food,
provides significant reductions in agricultural use of land,
water, fuel and other inputs.
Plants in both natural and cultivated populations carry
inherent disease resistance, but this has not always
protected them.

15. Non-protein amino acids
 Many plants also contain unusual amino acid called
non-protein amino.
 They exert their toxicity.
 block the synthesis of or uptake of protein amino
acid while other can be mistakenly incorporated
into protein.
 After ingestion, canavanine is recognized by
herbivore enzyme plants that synthesize non-
protein amino acids are not susceptible to the
toxicity of these compounds but gains defense to
herbivorous animals, insects and pathogenic
microbes.

16. Role of Secondary Metabolites in Defense
 For protect the plant from invading pathogens
 Helps to improve the shelf life of plant.
 Helps to keep the the plant healthy.
 Decreases the infection by some diseases and pests
also.
 Useful in preparation of perfumes, or aromatic
substances.
 It has virtually imp in attracting the animals for
pollination.
 Sometimes for else were for seed dispersal.
 Decreases the use of insecticides,pesticides,and
fungicides also.
 It improves the immunity of plant.

17. Applications
 It has wide application in pharmaceutical.
 In production of insecticides.
 In preparation of pesticides.
 In drug development.
 In preparation of antibiotics.
 Useful for the defense purpose.
 In plant it regulate the metabolism process.
 It acts as coloring agents itself

18. THANK YOU.