plant harmones by dilip kumar chandra

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Controls of growth, development Controls of growth, development and movement and movement By Dilip Kumar Chandra

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Page 1: Plant Harmones by dilip kumar chandra

Controls of growth, development Controls of growth, development and movementand movement

By Dil ip Kumar Chandra

Page 2: Plant Harmones by dilip kumar chandra

� Cell division.Cell division.� Cell enlargment.Cell enlargment.� Cell differentiation. Cell differentiation.

Page 3: Plant Harmones by dilip kumar chandra

Primary growthPrimary growth

Apical meristemApical meristem

Leaf primordiaLeaf primordia

Forming axillary budForming axillary bud

Ground meristemGround meristem

protodermprotoderm

procambiumprocambium

Page 4: Plant Harmones by dilip kumar chandra

Secondary growthSecondary growth

xylemxylem

Phloem withPhloem withbands of fibersbands of fibers

Vascular cambiumVascular cambium

Ray parenchymaRay parenchyma

corkcork

Page 5: Plant Harmones by dilip kumar chandra

� Scarification� mechanical� chemical� heat

� Mobilization of reserves

Page 6: Plant Harmones by dilip kumar chandra
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� Turgor movements (changes in turgor pressure in selected cells)

� Growth movements (elongation of selected cells in response to stimulus)� phototropism� geotropism� thigmotropism

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Directional movements in response to a directional stimulus

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GeotropismGeotropism

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� Signal molecules produced at specific locations.� Occur in low concentrations.� Cause altered processes in target cells at other

locations.

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Artificially synthesized substances which produce hormone like responses

Page 18: Plant Harmones by dilip kumar chandra

� Auxins� Gibberellins� Cytokinins� Abscisic acid� Ethylene

Page 19: Plant Harmones by dilip kumar chandra
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Auxin associated with phototropism - early experimentsAuxin associated with phototropism - early experimentsdemonstrate tip as receptor.demonstrate tip as receptor.

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Demonstration of transported chemicalDemonstration of transported chemical

Page 22: Plant Harmones by dilip kumar chandra

� Discovered as substance associated with phototropic response.

� Occurs in very low concentrations.� Isolated from human urine, (40mg 33 gals-1)� In coleoptiles (1g 20,000 tons-1)

� Differential response depending on dose.

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� abscission - loss of leaves� flower initiation� sex determination� fruit development

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infecteduninfected

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� General cell elongation.� Breaking of dormancy.� Promotion of flowering.� Transport is non-polar, bidirectional producing

general responses.

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Page 31: Plant Harmones by dilip kumar chandra

� Promotes cell division.� Morphogenesis.� Lateral bud development.� Delay of senescence.� Stomatal opening.� Rapid transport in xylem stream.

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� General growth inhibitor.� Causes stomatal closure.� Readily translocated.� Produced in response to stress.

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H H \ / C = C / \ H H

Page 35: Plant Harmones by dilip kumar chandra

� Gaseous in form.� Rapid diffusion.� Affects adjacent individuals.� Fruit ripening.� Senescence and abscission.� Interference with auxin transport.� Initiation of stem elongation and bud

development.

Page 36: Plant Harmones by dilip kumar chandra

� Constitutive enzymes - always present but level of hormone can affect level.

� Adaptive enzymes - formed or activated as a result of the presence of a hormone.

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Page 38: Plant Harmones by dilip kumar chandra

Interaction of cytokinin and auxinInteraction of cytokinin and auxinin tobacco callus tissuein tobacco callus tissue