Download Vascular Tissue

Biology 1030
Winter 2009
Reproduction, Development,
Form & Function
Chapter 35 (712-737)
Chapter 38 (771-782)
Scott circa 2009
Sporogenesis & Gametogenesis
• Two multicellular stages
– Two separate events
• Sporogenesis
– Sporangia of sporophyte
– Gametophytes
• Gametogenesis
– Gametangia of gametophyte
• Archegonia
• Antheridia
– Sporophytes
Scott circa 2009
1
Biology 1030
Winter 2009
Meiosis
• Does NOT produce gametes
p
g
• Sporangia
– Haploid spores
• Homospory
– All spores are visually identical
– Sex variable
• Heterospory
– 2 kinds of spores
• Megaspores
• Microspores
Scott circa 2009
Sex Determination
• Homospory
– Bryophytes – have sex chromosomes
• 50% female gametophytes
• 50% male gametophytes
– Pterophytes – hormonal sex determination
• Hermaphroditic – antheridiogen
• Male
• Heterospory
– Megaspores → female
– Microspores → male
– Differences in meiosis
Scott circa 2009
2
Biology 1030
Winter 2009
Gametogenesis
• ALWAYS by mitosis
• Gametangia
– Antheridia – multiple sperm
– Archegonia
A h
i – single
i l egg
Scott circa 2009
Gamete Transfer
• A major issue for plants
– Sessile
• Dependence on water
– Ancestral
• Mosses, ferns
– Reflected in structure
Scott circa 2009
3
Biology 1030
Winter 2009
Gamete Transfer
• Independence from water
– Derived characteristic
• Seed plants
– Male gametophyte transfer
• Wind
• Animals
– Pollination
Scott circa 2009
Gamete Transfer
• Pollen grain lands
• Gymnosperms
– Direct transfer – on/near micropyle
• Angiosperms
– Indirect transfer - stigma
– Pollen tube forms
• Tube cell – grows to micropyle
Scott circa 2009
4
Biology 1030
Winter 2009
Fertilization
• Non-flowering plants
– ‘Normal’
• Flowering plants
– Unique double fertilization
– 2 sperm required
• Generative cell divides
1. Egg + sperm = zygote
2. Sperm + 2 polar nuclei = endosperm
Scott circa 2009
The Seed
• Ovule after fertilization
• Compound structure
– Multiple
M lti l generations
ti
– Gymnosperms
1. Seed coat
2. Female gametophyte
3. Developing embryo
– Angiosperms
1. Seed coat
• Endosperm
2. Developing embryo
Scott circa 2009
5
Biology 1030
Winter 2009
The Seed
• Growth begins here
– Only one embryo per seed
• Induced dormancy
– Dehydration or temperature
– Required for germination
Scott circa 2009
Seed Dispersal
• Gymnosperms
– Seed coat extensions
– Wind
• Angiosperms - Fruit
– Wind
– Animals
– Turgor
Scott circa 2009
6
Biology 1030
Winter 2009
Embryo Development
• Zygote to embryo
– Within the seed
• Development of the organs
– What are they?
• Development of the tissue systems
– What
Wh t are they?
th ?
Scott circa 2009
Angiosperm Embryos
• Two Major types
• (Eu)dicots
– Two
T
seed
d leaves
l
• Monocots
– One
O seed
d leaf
l f
Seed coat
Endosperm
Cotyledons
Epicotyl
Hypocotyl
Radicle
Cotyledon
Pericarp fused
with seed coat
Endosperm
Epicotyl
Hypocotyl
Radicle
Scott circa 2009
7
Biology 1030
Winter 2009
Germination
• Breaking dormancy
1. Water
2 Oxygen
2.
3. Temperature
• Imbibition
– Ruptures coat
• Root emerges
• Shoot emerges
– Leaf primordia
Scott circa 2009
Angiosperm Embryos
• Epicotyl
– Shoot apical meristem
• Cotyledons
• Hypocotyl
• Radicle
– Root apical meristem
Scott circa 2009
8
Biology 1030
Winter 2009
Plant Tissues
• Three tissue systems
– In all organs
1. Vascular tissue
–
Transport
2. Dermal tissue
–
Protection
3. Ground tissue
–
Dermal
tissue
Storage, photosynthesis
Ground
tissue Vascular
tissue
Scott circa 2009
Vascular Tissue
Vessel
Tracheids
• Xylem – water & minerals
– Root → shoot
• Tracheids
• Vessel elements
• Tubular elongate cells
–
–
–
–
Thickened cell walls
Protoplast is dead
Conduit
Pits
Tracheids
Pit
Pits
Perforation
plate
Vessel
element
Scott circa 2009
9
Biology 1030
Winter 2009
Vascular Tissue
Sieve plate
Companion
• Phloem – photosynthates cells
– Shoot → root
– Root → shoot
• Living
• Sieve cells
• Sieve-tube elements
– Angiosperms
– Lack nucleus, etc.
Sieve-tube
elements
Plasmodesma
Sieve
plate
Nucleus of
companion
cells
• Companion cell
Scott circa 2009
Dermal Tissue
• Protective covering
• Primary – Epidermis
• Specialized structures
– Cuticle
– Stomata – guard cells
– Trichomes
• Secondary – Periderm
Scott circa 2009
10
Biology 1030
Winter 2009
Ground Tissue
• Consists of three cell/tissue types
1. Parenchyma
2. Collenchyma
3. Sclerenchyma
• Bulk of the plant body
Scott circa 2009
Parenchyma
• Thin cell walls & large vacuole
• Metabolically active cells
– Photosynthesis
Ph t
th i
– Storage
• Totipotent
– With stimuli
• Alive at maturity
Scott circa 2009
11
Biology 1030
Winter 2009
Collenchyma
• Clustered
• Supporting tissue
– Thicker
Thi k cell
ll wall
ll
• Flexible
– No lignin
• Alive at maturity
Scott circa 2009
Sclerenchyma
• Extensive secondary cell wall
• Lignified
• Often dead
• Sclerids
– Impart hardness
– Pear
• Fibres
– Impart strength
– Hemp
Scott circa 2009
12
Biology 1030
Winter 2009
Meristems
• Continual increase in length
– Primary growth
– Shoot apical meristem
– Root apical meristem
• Increase in girth
– Secondary growth
– Vascular cambium
– Cork cambium
Scott circa 2009
Plant Organs
• Three basic organs
• Below ground
Terminal bud
1 Roots
1.
R t
• Above ground
2. Stems (shoots)
3. Leaves
Vegetative
shoot
Shoot
system
Leaf
St
Stem
• Modifications on these
Root
system
Scott circa 2009
13
Biology 1030
Winter 2009
Roots
• Typically below ground
• Functions
–
–
–
–
–
Anchorage
Support
Absorption
Storage
Transport
• Trichomes
Dermal
Ground
• Tissues
Vascular
Scott circa 2009
Roots
• Primary root
– Embryo
• Lateral root
– Root
• Adventitious root
– Stem
• Fibrous root system
• Tap root system
Scott circa 2009
14
Biology 1030
Winter 2009
Root Growth
• Root cap
• Zone of division
– Root apical meristem
– Meristem cells
• Zone of elongation
– Pushes root tip
p
• Zone of maturation
– Primary tissues
Scott circa 2009
Cell Elongation
• Cell wall
• Meristem cells
1. Small vacuoles
2. Large vacuoles
3. Solute uptake
• Turgor pressure
4. Breaking cross bridges
• Wall pressure
5. Elongation
• Indeterminate growth
Scott circa 2009
15
Biology 1030
Winter 2009
Cell Maturation
• Concurrent with elongation
• Changes
– Morphological
M
h l i l
– Physiological
• Formation of:
– Vascular tissues
– Ground
G
d tissues
ti
– Dermal tissues
Scott circa 2009
Root Structure
• Dicot cross section
– Vascular tissue
• 1º
1 Xylem
• 1º Phloem
• Pericycle
Stele
– Ground Tissue
• Endodermis
• Cortex
– Dermal Tissue
• Epidermis
• Monocot
Scott circa 2009
16
Biology 1030
Winter 2009
Lateral Root Growth
• Pericycle
Root
apical
meristem
• Root apical meristem
– Zone of cell division
– Zone of cell elongation
– Zone of maturation
Vascular
cylinder
Cortex
Scott circa 2009
Modified Roots
•
•
•
•
Support
Aerial
Storage
Breathing
Scott circa 2009
17
Biology 1030
Winter 2009
Stems
• Typically above ground
– Rhizomes
• Functions
– Support
– Transport
– Photosynthesis
• Trichomes
• Tissues
Dermal
Ground
Vascular
Scott circa 2009
Stems
• Terminal bud
• Node
• Internode
• Axillary bud
Scott circa 2009
18
Biology 1030
Winter 2009
Stem Growth
• No cap
• Zone of division
– Shoot apical meristem
– Meristem cells
• Zone of elongation
– Pushes apex
p up
p
• Zone of maturation
– Primary tissues
– Primordial organs
Scott circa 2009
Stem Growth
• Elongation of internodes
–
–
–
–
Terminal bud
Newest internode
Second internode
Mature internodes
4
3
• Cell elongation
– Indeterminate
I d t
i t growth
th
• More complex
2
1
Scott circa 2009
19
Biology 1030
Winter 2009
Stem Growth
• Shoot apical meristem
• Three organs created
– Stem
– Leaf primordia
– Axillary buds
Scott circa 2009
Stem Structure
• Dicot cross section
– Vascular tissue
• 1º
1 Xylem
• 1º Phloem
Vascular
bundle
– Ground Tissue
• Pith
• Cortex
– Dermal Tissue
• Epidermis
• Monocot
Scott circa 2009
20
Biology 1030
Winter 2009
Modified Stems
• Horizontal
• Reduced
• Underground
Scott circa 2009
Leaves
• Major photosynthetic organ
• Functions
–
–
–
–
Photosynthesis
Transpiration
Gas exchange
Reproduction
• Trichomes
Dermal
• Tissues
Ground
Vascular
Scott circa 2009
21
Biology 1030
Winter 2009
Leaf Growth
• Shoot apical meristem
– Leaf primordia
• Midrib and midvein
• Blade
growth
• Determinate g
Scott circa 2009
Leaves
• Components
–
–
–
–
Petiole
Blade
Stipules
Axillary bud
• Simple leaves
• Compound leaves
Scott circa 2009
22
Biology 1030
Winter 2009
Leaf Structure
• Vascular tissue
– Xylem
– Phloem
• Ground Tissue
– Pallisade mesophyll
– Spongy mesophyll
– Air space
• Dermal Tissue
– Epidermis
Scott circa 2009
Leaf Function
• Requirements for photosynthesis
– CO2
– Water
• Products of photosynthesis
O2
Glucose
H2O
– Glucose
– O2
• Cellular respiration
CO2
Scott circa 2009
23
Biology 1030
Winter 2009
Stomata
• Gas exchange
• When are stomata open?
• When are they closed?
Scott circa 2009
Stomata
• Guard cells
– Microfibril orientation
– Inner cell wall
– Attachment
• Opening
1. Proton pump
– Electrochemical gradient
2 Potassium
2.
P t
i
flux
fl
– Hypertonic
3. Turgor pressure
Scott circa 2009
24
Biology 1030
Winter 2009
Abscission
• Dropping leaves
• Abscission zone
– Separation layer
– Protective layer
• Ion reclamation
• Cell wall breakdown
• Leaf scar
Scott circa 2009
Modified Leaves
•
•
•
•
•
Attachment
Defence
Storage
Reproduction
Advertizing
Scott circa 2009
Campbell
25
Biology 1030
Winter 2009
Flower Structure
• Reproductive shoot and leaves
•
•
•
•
p
Sepals
Petals
Stamen
Carpel
• Whorls
Scott circa 2009
Secondary Growth
• Increase in girth
• Woody plants
• Two meristems
Apical bud
Bud scale
Leaf
scar
Bud
scar
– Vascular cambium
– Cork cambium
Leaf scar
• First growing year
Bud scar
Scott circa 2009
26
Biology 1030
Winter 2009
Vascular Cambium
• Produces two tissues
• Secondary xylem
– Support
S
t
• Lignified cells
– Water/mineral transport
– Wood
– Produced annually
• Secondary phloem
– Photosynthate transport
– Inner bark
– crushed
Scott circa 2009
Vascular Cambium
• Initial
1. Cell division – daughter cells
2. Cell enlargement
3. Cell differentiation
– Secondary xylem
– Secondary phloem
Scott circa 2009
27
Biology 1030
Winter 2009
Annular Growth
• Variances in secondary xylem
• Early (spring) wood
– Large
L
vessels,
l tracheids
t
h id
• Late (summer) wood
– Small vessels, tracheids, fibres
Scott circa 2009
Cork Cambium
• Produces one tissue
• Cork
–
–
–
–
Suberin
S
b i
Prevents water loss
Protection
Epidermis isolation
• Tasks of the epidermis
p
• Periderm
Scott circa 2009
28
Biology 1030
Winter 2009
Cork Cambium
• Beneath epidermis
• De-differentiation
– Initial
I iti l
1. Cell division – daughter cells
2. Cell enlargement
3. Cell differentiation
– Cork cell
• Multiple cambia form
Scott circa 2009
All Together
Scott circa 2009
29