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Plant Structure, Growth, and Development

Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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Page 1: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Plant Structure, Growth, and Development

Page 2: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

• 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

Page 3: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

RootsRoots

– 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 siteepidermis, ground and vascular tissue.

Mycorrhizae: mutualistic fungi and plant roots.

35.1

Page 4: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Roots Cont.

http://belizebreeze.com/images/lamanai_tree_roots_rev_lowres.jpg http://quorumsensing.ifas.ufl.edu/HCS200/images/stems&roots/korni.jpg

Page 5: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:
Page 6: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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 plant’s 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.

Page 7: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Apical Dominance

Page 8: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Stems Cont.

http://www.infovisual.info/01/015_en.html

Page 9: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Xylem and phloem

Page 10: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Sieve cells

Page 11: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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

Page 12: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/images/stems/stems.4.jpg

Page 13: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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

Page 14: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Tissue System

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/leafstru.gif

Page 15: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Plant CellsType 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

Page 16: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Meristems generate cells for new organs

• 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

35.2 - 35.4

Page 17: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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.

Page 18: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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.

Page 19: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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.

Page 20: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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.

Page 21: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Growth, Morphogenesis, and the Differentiation Produce the Plant Body

• 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.

35.5

Page 22: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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 cross–links 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.

Page 23: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Preprophase Band

http://www.nature.com/nrm/journal/v2/n1/images/nrm0101_040a_f1.gif

Page 24: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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 individual’s 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.

Page 25: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Gene Expression

http://www.biosci.ohio-state.edu/~bdinglab/Research/Resear7.jpg

Page 26: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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.

Page 27: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

Juvenile vs. Adult Leaves

http://upload.wikimedia.org/wikipedia/en/c/ce/Pinus_pinea.jpg

Page 28: Plant Structure, Growth, and Development. Plant hierarchy: –Cells –Tissue: group of similar cells with similar function: Dermal, Ground, Vascular –Organs:

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 carpel’s. – 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.