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Plant Structure, Growth, and Development

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Title: Plant Structure, Growth, and Development


1
Plant Structure, Growth, and Development
2
  • Plant hierarchy
  • Cells
  • Tissue group of similar cells with similar
    function Dermal, Ground, Vascular
  • Organs multiple kinds of tissue, very diverse
    function
  • Organ systems
  • Organism

3
Roots
35.1
  • Roots
  • an organ that anchors a vascular plant.
  • Absorbs water inorganic nutrients
  • Storage of nutrients
  • Types of roots
  • Taproot Systems
  • Consist of one main vertical root
  • Gives rise to lateral roots (like branches)
  • Taproots store organic nutrients used in
    flowering and fruit production.
  • Fibrous Root System a mat of roots that spread
    out below the soil
  • Root Hair an extension of a root that gathers
    nutrients
  • Root cap covers root tip (apical meristem)
    primary growth site
  • epidermis, ground and vascular tissue.
  • Mycorrhizae mutualistic fungi and plant roots.

4
Roots Cont.
http//belizebreeze.com/images/lamanai_tree_roots_
rev_lowres.jpg
http//quorumsensing.ifas.ufl.edu/HCS200/images/st
emsroots/korni.jpg
5
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6
Stems
  • an organ consisting of an altering system of
  • nodes point where leaves are attached
  • internodes stem segments between nodes
  • Axillary bud a structure that potentially forms
    a lateral shoot otherwise known as a branch
  • At the end of this branch is a terminal end which
    develops leaves.
  • Apical Dominance
  • A phenomenon where the proximity of the terminal
    bud inhibits the growth of an axillary bud
  • This is an evolutionary adaption where resources
    are concentrated toward elongation it also
    increases the plants exposure to light.
  • If one is removed then the bud stimulates the
    growth of an axillary bud which produces more
    shoots.
  • That is why pinching back a plant makes it
    bushier.

7
Apical Dominance
8
Stems Cont.
http//www.infovisual.info/01/015_en.html
9
Xylem and phloem
10
Sieve cells
11
Leaves
  • the main photosynthetic organ of vascular plants
  • Leaves usually consist of
  • blade
  • petiole Joins the leave to a node on the stem
  • veins vascular tissues of the leaves
  • Veins are how monocots and dicots differ
  • Monocots have parallel veins
  • Endicots are multi branched
  • There are many different types of modified leaves
  • Spines, tendrils, storage, bracts (poinsettias),
    reproductive (succulents)

http//photos.somd.com/data/500/LEAF.jpg
12
http//academic.kellogg.cc.mi.us/herbrandsonc/bio1
11/images/stems/stems.4.jpg
13
Three Types of Tissue Dermal, Vascular, and
Ground
  • Tissue system one or more tissues organized
    into a functional unit
  • Dermal Tissue System
  • Outer protective covering (like skin)
  • Non woody plants single layer of epidermis
  • Cuticle A waxy coating on the leaves and the
    stems that helps prevent water loss.
  • Woody plants periderm replaces epidermis
  • Vascular Tissue System
  • Carries out long distance transport between root
    and shoot.
  • Two vascular tissues
  • Xylem conveys water and dissolved mineral up to
    shoots
  • Phloem transports organic nutrients to where
    they are needed.
  • Vascular tissue of a root stele
  • Ground Tissue System
  • Tissues that are neither dermal nor vascular

14
Tissue System
http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
leafstru.gif
15
Plant Cells
  • Type of cells found in plants
  • Parenchyma Cells a relatively unspecialized
    plant cell type that carries out most of the
    metabolism, synthesizes and stores organic
    products, and develops into a more differentiated
    cell type.
  • Guard cells
  • Sieve tube cells
  • Tracheoid cells
  • Palisade mesophyll Photosynthesis
  • Spongy mesophyll spaces allow the exchange of
    gases

16
Meristems generate cells for new organs
35.2 - 35.4
  • Apical meristems elongate shoots and roots
    through primary growth
  • With the process of primary growth it also allows
    roots to extend throughout the soil and for
    shoots to increase there exposure to light and
    CO2
  • Lateral meristems add girth to woody plants
    through secondary growth.
  • Root cap secretes a mucus that allows tip growth
    through soil

17
Primary Growth Roots
  • Primary growth produces the primary plant body.
  • ROOTS the root tip is covered by a thimble-like
    cap which protects the vulnerable apical meristem
    as the root pushed through the soil.
  • GROWTH occurs just behind the root tip, zone of
    cell division, elongation, and maturation.
  • The zone of cell division produced in the
    apical meristem
  • The zone of elongation, root cells elongate and
    new cell are added allowing the root to dive
    further into the soil.
  • The zone of Maturation, cells complete their
    differentiation and become functionally mature.

18
Primary Growth of Shoots
  • The apical meristem of a shoot is a dome shaped
    mass which is located in the terminal bud, where
    it gives rise to a repetiton of internodes and
    leaf bearing nodes.

19
The Vascular Cambium and secondary Vascular tissue
  • The vascular cambium develops from parenchyma
    cells into a meristematic cylinder that produces
    secondary xylem to the inside and secondary
    phloem to the outside.
  • Older layers of secondary xylem (heartwood)
    eventually become inactive.
  • Younger layers (sapwood) still conduct water.
  • Only the youngest secondary phloem is active.

20
Cork Cambia and the Production of Periderm
  • The cork cambia is a lateral meristem
  • Makes dermal tissue or periderm.
  • The bark on the other hand consists of all the
    tissues external to the vascular cambium which
    include secondary phloem and periderm.

21
Growth, Morphogenesis, and the Differentiation
Produce the Plant Body



35.5
  • Morphogenesis The development of body form and
    organization Each cell in the plant body contains
    the same set of genes, exact copies of the genome
    present in the fertilized egg.
  • Different patterns of gene expression among cells
    cause the cellular differentiation that creates a
    diversity of cell types.
  • The three developmental processes of growth,
    morphogenesis, and cellular differentiation act
    in concert to transform the fertilized egg into a
    plant.

22
Growth Cell Division and Expansion
  • Cell division and self-expansion are primary
    factors for growth
  • Plant cells rarely expand in all directions,
    their greatest expansion occurs in the plants
    main axis.
  • Growing plant cells expand mainly through water
    uptake. In a growing cell, enzymes weaken
    crosslinks in the cell wall, allowing it to
    expand as water diffuses into the vacuole by
    osmosis.
  • Orientation of the cytoskeleton also affects
    direction of cell elongation by controlling the
    orientation of cellulose micro fibrils.

23
Preprophase Band
http//www.nature.com/nrm/journal/v2/n1/images/nrm
0101_040a_f1.gif
24
Differentiation and Pattern Formation
  • Development of tissues and organs in specific
    locations (pattern formation) depends on cells
    ability to detect and respond to positional info.
  • Polarity-is the idea that a cell (egg) has diff.
    concentration of contents
  • Homeotic genes often control morphogenesis and
    also mediate many of the other events in an
    individuals development, such an initiation of
    an organ.
  • Gene Expression and control of Cellular
    Differentiation
  • Cellular differentiation selective gene
    expression
  • Cellular differentiation depends on a large
    extend on positional information, where a
    particular cell is located relative to other
    cells.

25
Gene Expression
http//www.biosci.ohio-state.edu/bdinglab/Researc
h/Resear7.jpg
26
Shifts in Development Phase Change
  • Internal or environmental cues may cause a plant
    to switch from one developmental phase to
    another.
  • From the development of juvenile leaves to the
    development of mature leaves, these are called
    phase changes.

27
Juvenile vs. Adult Leaves
http//upload.wikimedia.org/wikipedia/en/c/ce/Pinu
s_pinea.jpg
28
Genetic Control of Flowering
  • Research on organ identity genes in developing
    flowers provides an important model of pattern
    formation.
  • The ABC model of flower formation identifies how
    3 classes of organ identity genes control the
    formation of sepals, petals stamens, and
    carpels.
  • The floral organs develop in four circles, or
    whorls Sepals form the fourth (outermost) whorl
    petals form the third stamens form the second
    and carpels form the first (innermost) whorl.
    Plant biologists have identified several organ
    identity genes that regulate the development of
    this characteristic floral pattern. Organ
    identity genes, also called plant homeotic genes,
    code for transcription factors. Positional
    information determines which organ identity genes
    are expressed in a particular floral organ. The
    result is development of an emerging leaf into a
    specific floral organ, such as a petal or a
    stamen.
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