includes a brief introduction for plant growth regulators can be used as quick review for presentations for MSC,BSC students

1. PLANT GROWTH
REGULATORS

2. INTRODUCTION
• Phyto hormones are defined as organic compound synthesised in one part
of plant and translocated to another part where in low concentration
causes physiological response.
• The site of synthesis of plant hormones is not clearly localized.
• These hormones were first suggested by JULIUS VON SACHs.
• Plant hormones are able to produce their action locally or at a distance.

3. AMINOACIDS
TRYPTOPHAN -
IAA
METHIONINE –
ETHYLENE
ISOPRENOID
COMPOUNDS
CYTOKININS
GIBBERILLINS
ABSCISIC ACID
STRIGOLACTONES
BRASSINOSTERIODS
LIPIDS
JASMONIC ACID

4.  AUXIN was discovered by Frits Went as a growth promoting
chemical in the tip of oat coleoptiles.
 AUXIN is derived from Greek word Auxein : to increase
BIOSYNTHESIS AND TRANSPORT.
 Major sites are shoot apices ,young leaves ,developing fruits
and seeds.
 IAA conjugates are located exclusively in the cytosol.
 The path ways may be tryptophan dependent and
tryptophan independent.
 It shows strictly polar transport.

6. CELL
ELONGATION
CELL
DIFFERENTIATION
and DIVISON
ROOTING and
TROPISMS
APICAL
DOMINANCE
FRUIT SET AND
TROPIC
RESPONSE

7. • GIBBERELLINS are group of tetracyclic diterpenoid
compounds made of four isoprene units.
• GIBBERELLINS was first discovered by KURUSAWA in Japan
• Latter YABUTA isolated a active compound from the fungus
and named it as GIBBERELLIN.
• GIBBERELLINS are classified on the basis of structure and
function.
• Majority of gibberellins are acids and denoted by GA with a
subscript of GA1,GA2 ,GA3 ….etc.
• GA3-9 is found in higher plants while GA2 is obtained from
fungus.
• It delays the senescence and hastens the maturity period.
GIBBERELLINS

9. • These are synthesised primarily in the
apical tissues and young leaves.
• The highest levels are seen in
immature seeds and developing fruits.
• It mainly synthesise through
mevalonic pathway.
• It mainly transports in non polar.
BIOSYNTHESIS
AND
TRANSPORT

10. PHYSIOLOGICAL
EFFECTS OF
GIBBERELINS
• Effect on dwarf mutants
• Bolting and flowering
• Subtituting the cold treatment
• Breaking the dormancy
• Parthenocarpy
• Increase in size of leaves flowers and fruits
• Seed germination
• Flowering and sex expression

11. •Cytokinins are N6 substitused adenine derivatives that have
diverse effects on important physiological functions in plants.
•These are the substances that stimulate cell divisions.
•ZEATIN was the first cytokinin obtained from milky endosperm of
maize.
•Naturally occurring cytokinin are adenine a modified form of
kinetin.
•It occur in vascular plants and non vascular plants.
•These are present in apical meristems, developing seeds, roots,
fruits, cambial tissues.
CYTOKININS
• They are synthesised in young leaves, seeds ,fruits and root tips
from tips they are translocated through xylem.
• Two mechanisms for biosynthesis one leading to RNA cytokinins
and other is free cytokinins.
BIOSYNTHESIS
AND
TRANSPORT

13. Cell
enlargemen
t
Cell division
and
morphogene
sis
Breaking of
seed
dormancy
Counter
action of
apical
dominance
Retardation
of
senescence
Effect of
enzymes
Stomatal
movements

14. • It is also called stress hormone and first discovered by FREDRICK
T.ADDICOTT.
• It is present in all plant groups.
• ABA is a single compound.
• It was originally called Abscisin 2 because of its major role in abscission
• ABA is a sesquiterpene.
• It is almost synthesised in all cells that contain chloroplast and plastids.
• Naturally occurring ABA is most active form.
ABSCISIC ACID
• It is transported over long distances via xylem and phloem.
• The transport may be polar or non polar.
• It mainly synthesised in mature parts of plant.
BIOSYNTHESIS
AND
TRANSPORT

15. PHYSIOLOGICAL
EFFECTS OF ABA
• Growth inhibition
• Dormancy
• Abscission
• Fruit growth and flowering
• Senescence
• Stomatal movements

16. • It is a gaseous phytohormone unlike other hormones
• The ethylene has simple structure produced in higher
plants.
• This hormone is usually associated with fruit ripening and
triple response.
ETHYLENE
• Ethylene is mainly synthesised In all parts of higher plants
• Ethylene is biosynthesis is increased by stress conditions
such as drought, flooding, chilling, or mechanical
wounding.
• It moves by diffusion.
• The transport is passive process.
BIOSYNTHESIS
AND
TRANSPORT

17. PHYSIOLOGICAL
EFFECTS OF
ETHYLENE
• Abscission
• Ripening
• Effect of growth
• Degreening
• Senescence
• Flowering
• Dormancy
• Fruit Ripening
• Rooting etc

18. • Brassinosteriods are a group of steroidal plant
hormones.
• These are isolated from the pollen grains of
Brassica napus.
• These are similar to animal steroid hormones
synthesised from plant sterol CAMPESTROL.
• They promote cell elongation, cell division
,differentiation of xylem tissues.
• Plants with low Brassino steroids suffer from
dwarfism.
• The empirical formulae is C28H28O6
• Homo and epi Brassinosteriods are active and
widely in use when compared to others.
BRASSINOSTERIODS

19. • These are class of plant hormones isolated first from
plant root exudates of parasitic plant striga
• Strigolactones are terpenoid lactones derived from
carotenoids
• Strigol and orobranchol are two most commonly
naturally occurring
• They exhibit growth in plant and trigger the germination
of parasitic plant seeds
STRIGOLACTONES
• These are oxygenated fatty acids containing one or
more oxygen atoms other than those in carboxyl group.
• Best known Jasmonates are Jasmonic acid, Methyl
Jasmonate.
• These have anti herbivory and anti microbial functions.
• They participate in reproductive and vegetative
development.
JASMONATES

20. Taiz and Zeiger - plant physiology and development sixth
edition
http://en.Wikipedia.org/wiki/plant-hormone
http://technologyinscience.blogspot.com
Pranav kumar and Usha mina - life sciences seventh edition
path finder publication
Salisbury and Ross - Plant physiology
REFERENCES

21. THANK YOU