plant growth hormones(auxin and cytokinin)
TRANSCRIPT
Growth of flower parts ( Auxin)&
Growth of lateral buds (Cytokinins)
ByJewel
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Effect of Auxin
Cell division
Vascular tissue differentiation
Root initiation
Tropistic responses
Apical dominance
Leaf senescence
Leaf and fruit abscission2
Cont.
Fruit setting and growth
Assimilate partitioning
Fruit ripening
Flowering
Growth of flower parts
Promotes femaleness in dioecious flowers (via
ethylene)3
Introduction of auxin in flower parts Minor role - flowering and development of
reproductive organs
Necessary – for initiation of floral primordia
Specifying - number and identify of floral organ
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AuxinProduce in stem tip(bud), young leaves,
flower, fruit and shoot tip
Auxin promote pollen-tube growth towards the ovules
Family – Bromeliaceae a strong flower (Eg – pineapple) response
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Cont. Most plants - do not initiate the production of
flower (after auxin treatment)
Auxins in flower prevent flower formation
(under noninductive conditions)
Low amounts of promote flower formation auxin levels (under partial induction condition)
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Cont.In low concentrations delay the senescence
of flowers
IAA - promotes the formation of female flower - apparently stimulates the production of
ethylene.
Ethylene - important part of natural determination of flower sex.
Ethylene - involved flower opening (different ways) 7
Cont.Low conc; of ethylene - accelerate opening flower (Eg - carnation bud &roses)
Depending on cultivar
Lovely girl plants - strongly inhabit by low conc; ethylene
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Effect of cytokinin
Growth of lateral buds
Leaf expansion
Delay leaf senescence
Enhance stomatal opening in some species
Chloroplast development
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Cytokinin• Two types of cytokinins: Adenine-type cytokinins - kinetin,zeatin and
6 benzylaminopurine• Most adenine-type cytokinins - synthesized in roots.
Phenylurea-type cytokinins- diphenylurea and Thidiazuron(TDZ)
• Phenylurea cytokinins - no found in plants.10
Cont.Cytokinin occur in most plant – mosses, frens , conifers,
algae , diatoms
Zeatin – most active & naturally occur
Direct application– promote growth of lateral buds of cytokinin
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Growth of lateral buds in cytokinin
Moves from the roots into the shoots eventually signalling lateral bud growth.
Transpiration system in xylem promote bud growth by induction cell division
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Cont.High auxin suppresses release of lateral bud (from
dormancy)
While cytokinin stimulates their growth
Exogenous application of cytokinin – dormant lateral bud.
Auxin : Cytokinin – central factor controlling the growth of axillary bud 14
Exogenous auxin : cytokinin antagonistic
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Thank you very much
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• Lilium 'Lovely Girl' is: Deciduous• Flower: Reddish-brown, Yellow, White in Summer• Foliage: Green in Spring; Green in Summer; Green in Autumn• Habit: Clump-forming, Erect
Diatoms are algae with distinctive, transparent cell walls made of hydrated silica.
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