Botany - Week 4

Biotechnology

Technology that uses biological organisms or any parts of biological organisms

Genetic engineering

Manipulation of orgnanism’s genome

What are some examples of modern plant biotechnology? 

Tissue culture, GMO, mutagenesis, biofuels, etc… 

What is required for a successful tissue culture? 

1) Sterile environment 

2) Nutrient media 

3) Artificial lighting 

4) Knowledge of effects of hormones on growth/development 

What ration of cytokin and auxin are needed for callus formation in tissue cultures?

1:1

What ratio of auxin and cytokinin would be used for shoot induction in tissue cultures? 

1 auxin : 10 cytokinin 

What ratio of auxin and cytokinin would be needed for root induction in tissue cultures?

10 auxin : 1 cytokinin

Advantages of tissue culture

1) Rapid generation of large number of plants

2) Maintain traits of parent plants

3) Propagation of endangered species

4) Regeneration of plants after genetic modification

5) Ideal for plants with long life cycles and few seeds

Disadvantages of tissue culture 

1) Produces clones 

2) No genetic varation → disease spreads easily 

3) Somatic varions more common (mutations that occur in somatic cells) 

What are the benefits of genetic engineering?

1) Learn more about genes, proteins, and their collaborative functions

2) Increase crop performance

3) Produce important chemicals (vaccines, bioplastic, biofuel)

Disadvantages of traditional breeding

1) Slow 

2) No choice of genes mixed → keeps undesirable traits 

3) Limitations in breeding compatibility 

4) Lots of controversy over use of GMOs 

Recombitant DNA technology

Series of techniques used to manipulate and isolate DNA segments of interest

What is used for recombitant DNA technology?

Bacterial plasmid (vector) and cell containing DNA of interest

How does recombitant DNA technology work?

1) Bacterial plasmid and isolated gene of interest combined 

2) Recombitant DNA plasmid inserted back into bacterial cell (cloning) or into mammalian cell (transfection)

Plasmid

Separate piece of circular DNA located in bacteria

Transfection

Process of deliberately introducing naked/purified nucleic acids into eukaryotic cells

Classic steps of genetic engineering

1) Clone gene from organism (PCR to amplify gene and clone into bacterial plasmid)

2) Manipulate as necessary (change sequence, add promoter, remove parts of gene)

3) Insert into organism B (agrobacterium, gene gun)

4) Transgenic organism B

Polymerase Chain Reaction (PCR) 

Amplifying desired region of DNA using specific primers made to match two ends of that region 

What’s the most common method for transferring foreign genes into plants?

Agrobacterium (soil-borne bacterium)

How does gene transfer using agrobacterium work?

1) Genes inserted into TI plasmid

2) TI plasmid can send copies of gene into plant cells which then integrate into chromosomes

How do gene guns aid in gene transfer? 

1) Gold particles coated with copies of new gene 

2) Gold particles accelerated with air pressure and shot as callus cells on petri dish 

3) Gold particles land on nuclues → genese dissolve away from gold and incorporate into DNA of chromosome 

What are the steps for producing vaccines in plants? (Ex: tobacco)

1) Create virus vector carrying antigen gene 

2) Transfer gene into tobacco plant 

3) Extract antigen protein from leaves 

What are the steps for creating insecticidal plant? (Ex: cotton)

1) Soil bacteria produced by insecticidal protein

2) Transfer bacterial gene into cotton plant

3) Cotton plants now resistant

What are the main subterranean organs of plants? 

Roots 

What are the central aerial organs of plants?

Stems

Tap root development

1) Radicle dominates

2) Continues to dominate → tap root system

Fibrous root development 

1) Radicle stops elongating 

2) Many roots arise from base of stem 

3) Fibrous root system 

What is the benefit of having different types of root systems?

Help utilize resources more efficiently

Roles of roots

Food storage, secondary compound production, breathing, etc…

External structure of roots 

Lateral roots, root hairs, root cap, mucigel 

Internal sections of roots

Region of maturation, region of elongation, region of cell division

Structures found in region of maturation in roots

Mature and immature xylem

Structures found in region of elongation in roots 

1) Mature and immagure phloem 

2) Procambium 

3) Ground meristem 

Structures found in region of cell division in roots

1) Apical meristem

2) Root cap

Epidermis in root function

Absorption

*Root hairs increase surface area → more absorption

Cortex function 

Storage tissue 

Endodermis function

Barrier for water and minerals

Vascular bundle function

Transport of water and food

Casparian strip 

Band-like thickening in center of root endodermis

Function of casparian strip 

Stops non-selevtive absorption of materials into root from soil

Stem 

Above ground axel of plant 

Function of stem

Carry photosynthetic organs/reproductive organs; transport of food/water; reach for light

All herbaceous plants have ___

Non-woody stems

All trees have ___ 

Woody stems 

Rhizomes

Horizaontal underground stems

Anatomy of young monocot stem

Epidermis, vascular bundle, ground tissue

Anatomy of young dicot stem 

Epidermis, vascular bundles, ground tissue, pith, cortex 

How do dicot plants increase in width?

Transition to secondary growth → cells between vascular bundles become meristematic

Cork cambium

Ring of coritcal cells from lateral meristem

What is responsible for wood in stems and roots of woody dicot plants? 

Secondary xylem 

How do growth rings form?

Xylem added in slow growing season vs xylem added in fast growing season → can tell pattern

Dendrochronology

Scientific method of dating tree rings

Where does outer bark come from? 

Result of outward growth from cork cambium 

Inner bark

Phloem produced by vascular cambium