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Lecture 7 Growth and Development. Growth Irreversible change in Mass Development Irreversible change in State Embryogenesis Juvenile Adult Vegetative Adult Reproductive. Growth. Components 1. Cell Division 2. Cell Enlargement 3. Cell Differentiation. Cell Division.

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lecture 7 growth and development
Lecture 7Growth and Development
  • Growth
    • Irreversible change in Mass
  • Development
    • Irreversible change in State
      • Embryogenesis
      • Juvenile
      • Adult Vegetative
      • Adult Reproductive
growth
Growth
  • Components
  • 1. Cell Division
  • 2. Cell Enlargement
  • 3. Cell Differentiation
cell division
Cell Division
  • Meristematic Cells (Stem Cells)
  • Primary
    • Shoot Apical Meristem (SAM)
    • Root Apical Meristem (RAM)
  • Secondary
    • Axillary Buds
    • Vascular Cambium
    • Cork Cambium
    • Pericycle (root)
cell enlargement
Cell Enlargement
  • Adjacent to Meristems
  • Internode growth - Shoot
  • Zone of Elongation - Root
  • Turgor Pressure
      • H2O Uptake
      • Cell Wall Loosening
      • new cell walls
cell differentiation
Cell Differentiation
  • Cessation of Cell Enlargement
  • Secondary cell walls
  • Xylem - Vascular tissue
  • Fibers
  • Epidermal cells
  • root hairs
  • leaf hairs
  • guard cells
  • Leaves, Flowers
  • Fruit, Tubers, Bulbs, etc.
types of growth
Types of Growth
  • 1. Determinant

Terminal shoot apex flowers

  • 2. Indeterminant

Axillary buds flower

Terminal buds vegetative

  • 3. Monocarpic

Flower once then die

  • 4. Polycarpic

Flower repeatedly over several seasons

types of growth7
Types of Growth
  • 5. Annual

Monocarpic

Flower in one season and then die

  • 6. Biennial

Monocarpic

Flower in second season and then die

types of growth8
Types of Growth
  • 7. Herbaceous Perennial
  • Polycarpic
  • Determinant

Flower early and then go dormant

Flower Bulbs

  • Indeterminant
  • Flower throughout season
  • Shoot dies in Fall
types of growth9
Types of Growth
  • 8. Woody Perennial
  • Polycarpic
  • Indeterminant

flower only once per year

  • Biennial Bearing

flower and set fruit every other year

  • Mast Flowering

more prolific in some years than in others

dormancy
Dormancy
  • Ecodormancy
    • Imposed by Environment
    • Temperature, Daylength, etc.
  • Paradormancy
    • Physiological Dormancy
    • Apical Dominance
  • Endodormancy
    • True Dormancy
    • Seeds, Terminal Buds
plant growth regulators
PLANT GROWTH REGULATORS
  • 1. Endogenous
    • a. Substance produced by a plant that affects the pattern of growth and development.
    • b. Production by the plant is regulated by the environment.
  • 2. Exogenous
    • a. Substance applied to the plant that alters growth and development in the same way that endogenous substances do.
    • b. May be the same or different chemically from the endogenous substance
plant growth regulators12
PLANT GROWTH REGULATORS
  • 3. Hormone
    • a. Substance that acts in very low concentration (micro-molar or less)
    • b. Produced in one part of plant and act in another (translocatable)
    • c. Has the same response in many different plant species
plant growth regulators13
PLANT GROWTH REGULATORS
  • A. Primary
  • 1. Auxins
  • 2. Cytokinins
  • 3. Gibberellins
  • 4. Abscisic Acid
  • 5. Ethylene
plant growth regulators14
PLANT GROWTH REGULATORS
  • B. Secondary - newly discovered
  • 1. Jasmonic Acid
  • 2. Brassinosteroids
  • 3. Juglone
  • 4. Salicylic Acid
  • 5. Polyamines
plant growth regulators15
PLANT GROWTH REGULATORS
  • C. Others - not yet confirmed or understood
  • 1. Peptide Hormones

animals maybe plants

  • 2. Oligosaccharides

cell wall signaling

  • 3. Phospholipids

inositol phosphates, diacylglycerides

  • 4. mRNA or Protein

Florigen (floral induction)

natural auxin
Natural Auxin
  • 1. Endogenous
  • Indole Acetic Acid
auxin
Auxin
  • Synthesis
  • a. Young developing leaves
  • b. Terminal buds, growing axillary buds
  • c. Seeds
  • Transport
  • a. Basipetal

away from tip

  • b. Apoplastic

outside cells

  • c. Symplastic

through cells and plasmodesmata

  • d. Phloem – Conjugated Forms - Glycosides
auxin action
Auxin Action
  • Mechanism of Action
  • a. Bind Receptor Protein Plasma membrane
  • b. Transport into cell
  • c. Activate ATPase in Plasma membrane
  • d. H+ ion extrusion
  • e. acidify cell wall
  • f. break hemicellulose-pectin bonds
  • g. cellulose microfibrils slide apart
  • h. cell enlarges
auxin responses
Auxin Responses
  • Cell Enlargement
  • Shoot Growth
  • Internodes
  • Tubers
  • Bulbs
  • Root Growth
  • Storage Roots
  • Adventicious Roots
  • Fruit Growth
  • Strawberry - Receptacle enlargement
  • Apical Dominance
  • Auxin:Cytokinin Ratio
  • High - Dormant Axillary Buds
  • Low - Axillary Bud Growth
auxin agricultural uses
Auxin Agricultural Uses
  • Rooting of Cuttings

Propagation

Greenhouse and Nursery Crops

Hormodin, Rootone, etc.

Commercial preps of 2,4-D

  • Herbicide
  • High Concentration 2,4-D
  • Dicots more sensitive
  • Monocots less sensitive
  • Weed control in cereal crop production
  • Prevent Abscission of Leaves and Fruit
  • Older leaves
  • Ripe Fruit
  • Endogenous production of IAA stops
  • Replaced by exogenous NAA
auxin agricultural uses27
Auxin Agricultural Uses
  • Chemical Thinning
  • Differential sensitivity of developing fruit
  • High Concentration of NAA causes abscission
  • Induction of Ethylene Synthesis
  • Tissue Culture Propagation
  • Auxin:Cytokinin Ratio
  • High - Roots
  • Low - Shoots
  • Equal - Callus
cytokinins

NH2

ATP

N

DNA

N

RNA

N

N

NAD(P)

(ribose)

Adenine

(Adenosine)

CH3

N-CH2-C=C-CH2-OH

N

N

N

N

(Ribose)

Zeatin

(Riboside)

Cytokinins
  • Adenine + Ribose
    • Adenosine
  • ATP, ADP, AMP
  • DNA, RNA
  • Nucleotides
    • NAD, NADP, FAD
  • Cytokinins
    • Cis & Trans Zeatin
    • + Ribose
      • Zeatin Riboside
cytokinins30
Cytokinins
  • Synthesis
    • Root Apex
  • Transport
    • Upward in Xylem
cytokinins31
Cytokinins
  • Responses
  • Stimulate Cell Division
  • Apical Dominance
  • High Auxin in Shoot Apex
  • High Cytokinin in Root Apex
  • Gradient Between:
  • High Auxin:Cytokinin
  • Dormant Axillary Buds
  • Low Auxin:Cytokinin
  • Branch Growth
cytokinins32
Cytokinins
  • Synthetic Cytokinins
  • Kinetin

DNA degredation

  • Benzyladenine (BA or 6-Benzyl amino purine)
  • Agricultural Uses
  • Limited
  • Induction of Axillary Buds

Roses, Chrysanthemum

  • Micropropagation

Shoot proliferation in Tissue Culture

gibberellins
Gibberellins
  • Family of more than 70 structures like this
  • Synthesis
  • Fungal product
  • Gibberella fugikuroi
  • Many other pathogens
  • Plant Product
  • Normal growth and elongaton
gibberellins34

O

C=O

HO

OH

CH3

C

CH2

HO

O

GA1

Gibberellins
gibberellins35
Gibberellins
  • Inactive Active
gibberellins36
Gibberellins
  • Synthesis
    • Starts in Plastids (Carotenoid Pathway)
    • Modified in ER
    • Completed in Cytoplasm
  • Tissue Localization
    • SAM, Young Leaves, Apical Internodes
    • Developing Fruit, Germinating Seed
    • Roots
  • Transport
    • Xylem and Phloem
gibberellins37
Gibberellins
  • Responses
  • Cell Elongation
  • Dwarf cultivars

eg. Peas (Little Marvel)

  • Dwarfing rootstocks

apples, pears, peaches

height from roots

fruit quality from scion

  • Seed Dormancy

High ABA

Reversed by GA application

Synthesis of GA by embryo

gibberellins39
Gibberellins
  • Agricultural Uses
  • 1. Thompson Seedless Grapes

Principal use

Parthenocarpic Fruit

  • 2. Seed Germination

Malting Barley

Precocious germination

  • 3. Male Flower production

Monoecious & Dioecious Plants

  • 4. Chilling Requirement

Azaleas

Biennials

Biennial Bearing

ethylene

H

H

C = C

H

H

Ethylene
ethylene41
Ethylene
  • C2H4
  • Gas at room temperature
  • Synthesis

|Hemicellulose

+ATP |

Methionine ---> SAM ---> ACC ---> Ethylene ---> PG

1 2 | 3 |Galactose

  • 1. S-Adenosyl Methionine
  • 2. Amino Cyclo Propane
  • 3. Polygalacturonase
ethylene42
Ethylene
  • Agricultural Uses
    • Ethaphon - breaks down to form ethylene
  • 1. Fruit Ripening

Tomato, Banana, Melon, etc.

Pick unripe and firm for shipping

Spray in store to "ripen"

Color development and softening

Field Spray

Uniform and synchronous ripening

Canning Tomatoes

Mechanical Harvest

ethylene43
Ethylene
  • 2. Floral Development

Bromeliads

Pineapple

Banana

Uniform development of inflorescence

  • 3. Sex Expression

Female Flowers

Curcubits

opposite of GA action

  • 4. Degreening of Citrus

Oranges, Lemons, Grapefruit

Break down Chlorophyll

Leaves Carotenoids

ethylene44
Ethylene
  • 5. Mechanical Harvesting

Formation of Abscission Zone

Stimulate Fruit Drop

Cherries, Walnuts, Pecans

  • 6. Postharvest Shelf Life

block ethylene synthesis

AgNO3 or Silver Thiosulfate

delay senescence

Carnations

abscisic acid

O

CH3

CH3

CH3

C

OH

OH

O

CH3

Abscisic Acid
abscisic acid46
Abscisic Acid
  • Natural Plant Growth Retardant

Opposes action of GA and Auxin

  • Synthesis

Chloroplasts

Breakdown product of Carotenoids

abscisic acid47
Abscisic Acid
  • Responses
  • Dormancy Maintenance

high levels in dormant seed and buds

  • Drought Resistance

causes stomatal closure

  • Agricultural Uses

None

synthetic growth retardants
Synthetic Growth Retardants

1. Daminozide (Alar, B-9)

Retard growth

Stimulate Flowering

Chrysanthemums, Azaleas

Chemical Pruning

Apple

Enhance size and color

  • 2. Chlormequat (CCC, Cycocel)

Promote branching

Poinsettia, Geraniums, Bouganvillia

Prevent Lodging of Wheat

synthetic growth retardants49
Synthetic Growth Retardants
  • 3. Ancymidol (A-Rest)

Height Control of bulb produced plants

Lily, Tulip

  • 4. Paclobutrazol (Bonzai)

Micropropagation

Stimulates Rooting