Download CPB735_TXT

Chapter 35
Plant Structure, Growth, and
Development
PowerPoint TextEdit Art Slides for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.1 Fanwort (Cabomba caroliniana)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.2 An overview of a flowering plant
Reproductive shoot (flower)
Terminal bud
Node
Internode
Terminal
bud
Shoot
system
Vegetative
shoot
Leaf
Blade
Petiole
Axillary
bud
Stem
Taproot
Lateral roots
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Root
system
Figure 35.3 Root hairs and root tip
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.4 Modified roots
(a) Prop roots
(b) Storage roots
(d) Buttress roots
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
(c) “Strangling” aerial
roots
(e) Pneumatophores
Figure 35.5 Modified stems
(a) Stolons. Shown here on a
strawberry plant, stolons
are horizontal stems that grow
along the surface. These “runners”
enable a plant to reproduce
asexually, as plantlets form at
nodes along each runner.
Storage leaves
(d) Rhizomes. The edible base
of this ginger plant is an example
of a rhizome, a horizontal stem
that grows just below the surface
or emerges and grows along the
surface.
Stem
Node
Root
(b) Bulbs. Bulbs are vertical,
underground shoots consisting
mostly of the enlarged bases
of leaves that store food. You
can see the many layers of
modified leaves attached
to the short stem by slicing an
onion bulb lengthwise.
Rhizome
(c) Tubers. Tubers, such as these
red potatoes, are enlarged
ends of rhizomes specialized
for storing food. The “eyes”
arranged in a spiral pattern
around a potato are clusters
of axillary buds that mark
the nodes.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Root
Figure 35.6 Simple versus compound leaves
(a) Simple leaf. A simple leaf
is a single, undivided blade.
Some simple leaves are
deeply lobed, as in an
oak leaf.
Petiole
(b) Compound leaf. In a
compound leaf, the
blade consists of
multiple leaflets.
Notice that a leaflet
has no axillary bud
at its base.
Axillary bud
Leaflet
Petiole
Axillary bud
(c) Doubly compound leaf.
In a doubly compound
leaf, each leaflet is
divided into smaller
leaflets.
Leaflet
Petiole
Axillary bud
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.7 Modified leaves
(a) Tendrils. The tendrils by which this
pea plant clings to a support are
modified leaves. After it has “lassoed”
a support, a tendril forms a coil that
brings the plant closer to the support.
Tendrils are typically modified leaves,
but some tendrils are modified stems,
as in grapevines.
(b) Spines. The spines of cacti, such
as this prickly pear, are actually
leaves, and photosynthesis is
carried out mainly by the fleshy
green stems.
(c) Storage leaves. Most succulents,
such as this ice plant, have leaves
modified for storing water.
(d) Bracts. Red parts of the poinsettia
are often mistaken for petals but are
actually modified leaves called bracts
that surround a group of flowers.
Such brightly colored leaves attract
pollinators.
(e) Reproductive leaves. The leaves
of some succulents, such as Kalanchoe
daigremontiana, produce adventitious
plantlets, which fall off the leaf and
take root in the soil.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.8 The three tissue systems
Dermal
tissue
Ground
tissue
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Vascular
tissue
Figure 35.9 Examples of Differentiated Plant Cells
PARENCHYMA CELLS
WATER-CONDUCTING CELLS OF THE XYLEM
Tracheids
Vessel
100 m
Pits
Parenchyma cells
60 m
COLLENCHYMA CELLS
Cortical parenchyma cells
80 m
Tracheids and vessels
Vessel
element
Vessel elements with
partially perforated
end walls
Tracheids
SUGAR-CONDUCTING CELLS OF THE PHLOEM
Sieve-tube members:
longitudinal view
Collenchyma cells
SCLERENCHYMA CELLS
5 m
Companion
cell
Sclereid cells
in pear
Sieve-tube
member
25 m
Sieve
plate
Nucleus
Cell wall
30 m
15 m
Cytoplasm
Fiber cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Companion
cell
Figure 35.10 An overview of primary and
secondary growth
Primary growth in stems
Shoot apical
meristems
(in buds)
Epidermis
Cortex
In woody plants,
there are lateral
meristems that
add secondary
growth, increasing
the girth of
roots and stems.
Primary phloem
Vascular
cambium
Cork
cambium
Primary xylem
Lateral
meristems
Pith
Secondary growth in stems
Apical meristems
add primary growth,
or growth in length.
Pith
Primary
xylem
Root apical
meristems
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Secondary
xylem
Periderm
Cork
cambium
The Cork
cambium adds
secondary
dermal tissue.
Cortex
Primary
phloem
The vascular
cambium adds
Secondary
secondary
phloem
xylem and
Vascular cambium
phloem.
Figure 35.11 Three years’ past growth evident in a winter twig
Terminal bud
Bud scale
Axillary buds
Leaf scar
Node
This year’s growth
(one year old)
Stem
Internode
One-year-old side
branch formed
from axillary bud
near shoot apex
Leaf scar
Last year’s growth
(two years old)
Scars left by terminal
bud scales of previous
winters
Leaf scar
Growth of two
years ago (three
years old)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.12 Primary growth of a root
Cortex
Vascular cylinder
Epidermis
Key
Root hair
Dermal
Zone of
maturation
Ground
Vascular
Zone of
elongation
Apical
meristem
Root cap
100 m
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Zone of cell
division
13.12 Time Lapse Root
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.13 Organization of primary tissues in young roots
Epidermis
Cortex
Vascular
cylinder
Endodermis
Pericycle
Core of
Parenchyma
cells
Xylem
100 m
Phloem
100 m
(a) Transverse section of a typical root. In the
roots of typical gymnosperms and eudicots, as
well as some monocots, the stele is a vascular
cylinder consisting of a lobed core of xylem
with phloem between the lobes.
Endodermis
Pericycle
(b) Transverse section of a root with parenchyma
in the center. The stele of many monocot roots
is a vascular cylinder with a core of parenchyma
surrounded by a ring of alternating xylem and phloem.
Key
Dermal
Ground
Vascular
Xylem
Phloem
50 m
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.14 The formation of a lateral root
100 m
Emerging
lateral
root
Cortex
1
Vascular
cylinder
2
Epidermis
Lateral root
3
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
4
Figure 35.15 The terminal bud and primary growth of a shoot
Apical meristem
Leaf primordia
Developing
vascular
strand
Axillary bud
meristems
0.25 mm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.16 Organization of primary tissues in young stems
Phloem
Xylem
Sclerenchyma
(fiber cells)
Ground
tissue
Ground tissue
connecting
pith to cortex
Pith
Epidermis
Key
Cortex
Epidermis
Vascular
bundle
1 mm
Dermal
Ground
Vascular
(a) A eudicot stem. A eudicot stem (sunflower), with
vascular bundles forming a ring. Ground tissue toward
the inside is called pith, and ground tissue toward the
outside is called cortex. (LM of transverse section)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Vascular
bundles
1 mm
(b) A monocot stem. A monocot stem (maize) with vascular
bundles scattered throughout the ground tissue. In such an
arrangement, ground tissue is not partitioned into pith and
cortex. (LM of transverse section)
Figure 35.17 Leaf anatomy
Key
to labels
Guard
cells
Dermal
Ground
Vascular
Cuticle
Stomatal pore
Epidermal
cell
Sclerenchyma
fibers
50 µm
(b) Surface view of a spiderwort
(Tradescantia) leaf (LM)
Stoma
Upper
epidermis
Palisade
mesophyll
Bundlesheath
cell
Spongy
mesophyll
Lower
epidermis
Guard
cells
Cuticle
Xylem
Phloem
Vein
Guard
(a) Cutaway drawing of leaf tissues cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Vein
Air spaces
Guard cells
(c) Transverse section of a lilac 100 µm
(Syringa) leaf (LM)
Figure 35.18 Primary and secondary growth of a stem (layer 1)
(a) Primary and secondary growth
in a two-year-old stem
1
Pith
Primary xylem
Vascular cambium
Primary phloem
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Epidermis
Cortex
Figure 35.18 Primary and secondary growth of a stem (layer 2)
1
(a) Primary and secondary growth
in a two-year-old stem
Pith
Primary xylem
Vascular cambium
Primary phloem
3 Xylem 2
ray
Primary
xylem
Secondary xylem
Vascular cambium
Epidermis
Cortex
Phloem ray
Cork
4 First cork cambium
Primary phloem
Secondary phloem
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.18 Primary and secondary growth of a stem (layer 3)
1
(a) Primary and secondary growth
in a two-year-old stem
Epidermis
Cortex
Primary phloem
Vascular cambium
Primary xylem
Pith
Primary xylem
Vascular cambium
Primary xylem
Pith
3 Xylem 2
ray
Primary
xylem
Secondary xylem
Vascular cambium
Epidermis
Cortex
Phloem ray
Cork
4 First cork cambium
Primary phloem
Secondary phloem
Periderm
(mainly cork
cambia
and cork)
6
9 Bark
Primary phloem
8 Layers of
periderm
Secondary phloem
Vascular cambium
Secondary xylem
Primary xylem
Pith
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Secondary
xylem
(two years of
production)
Vascular cambium
7 Cork
5 Most recent
Secondary phloem
cork cambium
Secondary phloem
Vascular cambium
Cork
cambium
Cork
Secondary Late wood
Early wood
xylem
Periderm
(b) Transverse section
of a three-yearold stem (LM)
Xylem ray
Bark
0.5 mm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
0.5 mm
Figure 35.19 Cell division in the vascular cambium
Vascular
cambium
(a) Types of cell division. An initial can divide
transversely to form two cambial initials (C)
or radially to form an initial and either a
xylem (X) or phloem (P) cell.
C
(b) Accumulation of secondary growth. Although shown here
as alternately adding xylem and phloem, a cambial initial usually
produces much more xylem.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.20 Anatomy of a tree trunk
Growth ring
Vascular
ray
Heartwood
Secondary
xylem
Sapwood
Vascular cambium
Secondary phloem
Bark
Layers of periderm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.21 Arabidopsis thaliana
Unknown
(36.6%)
Cell organization and biogenesis (1.7%)
DNA metabolism (1.8%)
Carbohydrate metabolism (2.4%)
Signal transduction (2.6%)
Protein biosynthesis (2.7%)
Electron transport
(3%)
Protein
modification (3.7%)
Protein
metabolism (5.7%)
Transcription (6.1%)
Other metabolism (6.6%)
Other biological
processes (18.6%)
Transport (8.5%)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.22 The plane and symmetry of cell division
influence development of form
Division in
same plane
Single file of cells forms
Plane of
cell division
Division in
three planes
Cube forms
Nucleus
(a) Cell divisions in the same plane produce a single file of cells, whereas cell divisions in three planes give rise to a cube.
Asymmetrical
Developing
guard cells
cell division
Unspecialized
epidermal cell
Unspecialized
epidermal cell
Guard cell
“mother cell”
Unspecialized
epidermal cell
(b) An asymmetrical cell division precedes the development of epidermal guard cells, the cells that border stomata (see Figure 35.17).
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.23 The preprophase band and the plane
of cell division
Preprophase bands
of microtubules
Nuclei
Cell plates
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
10 µm
Figure 35.24 The orientation of plant cell expansion
Cellulose
microfibrils
Vacuoles
Nucleus
5 µm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.25 The fass mutant of Arabidopsis confirms the
importance of cytoplasmic microtubules to plant growth
(b) fass seedling
(a) Wild-type seedling (c) Mature fass mutant
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.26 Establishment of axial polarity
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.27 Overexpression of a homeotic gene in
leaf formation
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.28 Control of root hair differentiation by
a homeotic gene
When epidermal cells border a single cortical
cell, the homeotic gene GLABRA-2 is selectively
expressed, and these cells will remain hairless. Here an epidermal cell borders two
cortical cells. GLABRA-2 is not expressed,
(The blue color in this light micrograph indiand the cell will develop a root hair.
cates cells in which GLABRA-2 is expressed.)
Cortical
cells
20 µm
The ring of cells external to the epidermal layer is composed of root
cap cells that will be sloughed off as
the root hairs start to differentiate.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.29 Phase change in the shoot system of Acacia koa
Leaves produced
by adult phase
of apical meristem
Leaves produced
by juvenile phase
of apical meristem
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 35.30 Organ identity genes and pattern
formation in flower development
Pe
Ca
St
Se
Pe
Se
(a) Normal Arabidopsis flower. Arabidopsis
normally has four whorls of flower parts: sepals
(Se), petals (Pe), stamens (St), and carpels (Ca).
(b) Abnormal Arabidopsis flower. Reseachers have
identified several mutations of organ identity
genes that cause abnormal flowers to develop.
This flower has an extra set of petals in place of
stamens and an internal flower where normal
plants have carpels.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Pe
Pe
Se
Figure 35.31 The ABC hypothesis for the functioning
of organ identity genes in flower development
Sepals
Petals
Stamens
A
Carpels
B
(a) A schematic diagram of the ABC
hypothesis. Studies of plant mutations
reveal that three classes of organ identity
genes are responsible for the spatial pattern
of floral parts. These genes are designated A,
B, and C in this schematic diagram of a floral
meristem in transverse view. These genes
regulate expression of other genes
responsible for development of sepals,
petals, stamens, and carpels. Sepals develop
from the meristematic region where only A
genes are active. Petals develop where both
A and B genes are expressed. Stamens arise
where B and C genes are active. Carpels arise
where only C genes are expressed.
C
C gene
activity
A+B B+C
gene gene
activity activity
A gene
activity
Active
genes:
Whorls:
BB
BB
A ACCCCA A
BB
BB
CCCCCCCC
A ACCCCA A
AA
AA
ABBAABBA
Mutant lacking A
Mutant lacking B
Mutant lacking C
Carpel
Stamen
Petal
Sepal
Wild type
(b) Side view of organ identity mutant flowers. Combining the model
shown in part (a) with the rule that if A gene or C gene activity is
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
missing, the other activity spreads through all four whorls, we can explain the
phenotypes of mutants lacking a functional A, B, or C organ identity gene.