1. Plant Tissues and Meristems
Protects against physical/pathogenic agents, prevents water loss
All derived from meristematic tissue
Thin walled cells
Functions: storage, photosynthesis, support, secretion
Xylem/phloem: carryout long distance conduction (water, minerals, nutrients), provide support
Divide: 1 stem cell/1 differentiated cell
Continually renewed

2. Plant Growth
Plants
Continual pattern of growth
Animals/leaves
Growth ceases at a point
Death:
Annuals (die yearly)
Biennials (2yr cycle)
Perennials (die due to infection, environmental factors)

3. Meristems
Grow tall to increase exposure to light, CO2
2⁰ meristem: increase thickness of stem/root
1⁰ meristem
Herbaceous, non-woody plants
Woody plants
Produces cork cells of outer bark
Extends into soil
Produces 2⁰ vascular tissue

4. Plant Hormones
Means of communication within plant
Affect development and growth:
Environmental stimulus (day length/water)
Receptor types (detection of factors)
Genetic makeup
Hormones

5. Process of Hormone signaling
Specific cells have specific receptors
Receive environmental stimulus
Protein receptor activated
Initiates metabolic pathway
Produces hormone (produced throughout plant)
Travel via phloem
Target cell  affects specific area of plant

6. Auxin and Phototropism
Tropisms: growth/movement to directional external stimuli
Positive - towards
Negative - away
Phototropism: response to light
Stems (+)
Roots (-)
Increases flexibility of cell walls in young plants
Auxin found in 1⁰ apex)
Redistributed to shaded side
Creates curvature towards light

7. Auxin and Phototropism
1. Auxin produced in all cells in stem on light side (auxin efflux)
2. Auxin influx: pump action into nuclei of cells on dark side
3. Auxin and receptor form complex – activates H+ pump
4. H+ move into cell wall
5. Causes pH drop creating H-bonds between cellulose fibers – breaking cell wall
Causes elongation

8. Auxin involved with:
Stimulation of cell division in meristematic tissue
Xylem/phloem differentiation
Development of lateral roots
Suppress lateral bud growth when found in apical bud
Stimulate growth of flower parts
Fruit production without pollination
Changes in gene expression

9. Micropropogation
Culture cells from shoot apex
Nutrient agar with growth hormones
Uses:
Rare/endangered plants maintained
Develop virus-free strains
Alter genome to create beneficial plants
Problems:
Extremely expensive
Difficult to maintain pathogen free environment