secondary metabolites

1. TOPIC: SECONDARY METABOLITIES IN PLANT
DEFENCE MECHANISM
COURSE INSTRUCTOR : DR. GURDEV CHAND
PRESENTED BY : ASRAR AHMAD
REG.NO : (J-18-M-565)
DIVISION : FRUIT SCIENCE
SHER-E-KASHMIR UNIVERSITY OF AGRICULTURAL
SCIENCE AND TECHNOLOGY- JAMMU

2. Ex: Proteins, Carbohydrates , Ex :Morphine, Caffene,
fats ,lipids and nucleotides . nicotine, codine.
INTRODUCTION
I. Primary metabolites
Metabolites
Secondary metabolites

3. Classification of secondary metabolites
1. Terpenes ( 25,000 types)
2. Phenolic compounds(8,000 types)
3. Glycosides
4. Alkaloids

4. Pie chart representing the major
group of secondary metabolites

5. • Some are volatile and insoluble in water.
• Terpenes contain resin acid and some hydrocarbons.
isopentene isoprene
• Terpenes are classified by the number of isoprene units they contain
TERPENES

6. Outline of terpenes biosynthetic pathway

7. Monoterpenes ( 2 isoprene unit)
• Pyrethriods (insecticidal activity).
• Limone, camphor (medicinal).
Sesquiterpenes ( 3 isoprene unit)
• Phytohormone (abscisic acid). Antibiotic (pentalenolactone).
• Anti-cancer (gossypol).
Diterpenes (4 isoprene unit)
• Anti-cancer drug (taxol), Phytohormone (gibberellin).
Triterpenes (6 isoprene unit) : Membrane component (sitosterol).
Tetraterpenes (8 isoprene unit) : Plant pigment (beta-carotene)
Classes of terpenes and their ecological
significance

8. 1. Terpenes defend many Plants against Herbivores
• Terpenes are toxins and feeding deterrents to many plant
feeding insects and mammals; thus they appear to play
important defensive roles in the plant kingdom.
(Gershenzon and Croteau 1992).
Example: Pyrethroids (insecticidal activity) in chrysanthemum.
• Many conifers respond to bark beetle infestation by producing
additional quantities of monoterpenes
(Trapp and Croteau 2001).
Role of terpenes

9. • Peppermint oil is menthol, Lemon oil is limonene.
• Essential oils have well-known insect repellent properties.
3. Terpene Antiherbivore Compounds
• Phytoecdysones, limonoids
2. Volatile Terpenes (Essential Oils)

10. • OH and aromatic ring containing secondary
metabolites.
• Some are soluble in organic solvents, some are
water-soluble carboxylic acids and glycosides,
and other are large, insoluble polymers
• Ubiquitous in all plant organs.
Phenolic compounds

11. 1. Serve as defenses against herbivores and pathogens.e.g,
lignin, tannins.
2. Mechanical support,eg, taninnins and lignins.
3. In absorbing harmful ultraviolet radiations
4. In reducing the growth of nearby competing plants, e.g,
caffeic acid and ferulic acid.
5. In attracting pollinators, e.g anthocyanins
Functions of phenolics

12. 1. Cumarins (Scopoletin and Dicoumarol)
2. Lignin
3. Flavonoids-largest class and further
devided into anthocyanins, flavones,
flavonols, isoflavonoids, etc.
4. Tannins
Classes of
Phenolics

13. Biosynthetic pathways of phenolics

14. Most important glycosides
Protective function in plants and also used as medicine( Digoxin).
3. Glycosides
Saponins (containing a steroid or triterpenoid aglycone )
Cardiac glycosides (Steriod) eg, Digoxin
Cyanogenic glycosides (Aglycone containing a cyanide group)
Role

15. • Contain at least one nitrogen atom in their
chemical structure.
• Alkaline in nature.
• Water soluble.
Alkaloids

16. • Provide defense against microbial infection and herbivoral
attack.
• Provide defense against predators (strychnine).
• Repel feeders
Precursor molecules
Lysine
Phenylalanine
Tyrosine, Histadine
Role in plants
Biosynthesis of alkaloids

17. Major types of alkaloids

18. Major pathways of secondary metabolites

19. conclusion
Secondary metabolites and their role.
• Induced plant defense and constitutive.
• Plant defense against pathogen- hypersensitive reactions,
hydrolytic enzymes, microbe-associated molecular patterns.
• Human diet and medicinal properties.