Lecture 10 - Seeds, Meristems and PCR

Functions of a seed

1. Protects young plant at early developmental stage

2. Provides energy reserve for growing plant before photosynthesis is possible

3. Dispersal mechanics

4. Can maintain dormancy until conditions are adequate for growth

Seed dormancy

It is a strategy that prevents growth until conditions are adequate. It can last from days to years.

Desert plant dormancy

Dormancy ends after heavy rainfall

Chaparral dormancy

Occurs after exposure to fire/smoke and when older vegetation is cleared

Other dormancy breaking conditions

• Cold

• Sunlight

• Passage through animal’s digestive system

Events of seed germination process

1. Water absorption causes swelling, seed coat is ruptured

2. Metabolic changes restarts growth of embryo

3. Stored materials broken down by enzymes, nutrients and sugar are transferred to parts of the growing plant

4. Radicle (emb. root) emerges from seed

Determinate growth program

Growth is fixed by genetic parameters

Indeterminate program

Growth is not limited by genetics and can continue indefinitely as long as environmental conditions permit

Meristem

Region of undifferentiated cells from which new cells arise

Two properties of meristems

1. Ability to self-renew

2. Ability to produce cells that can further differentiate into various cell types

Property of all nucleated cells

All nucleated cells are totipotent

Totipotency in plants

Ability to differentiate into any other cell types, or develop into its own plant

Function of apical meristem

Elongation growth

Types of Apical Meristem

• Shoot apical meristem

• Root apical meristem

3 Types of Primary Meristem produced by Apical Meristem

• Protoderm

• Procambium

• Ground Meristem

Label the Apical Meristem types

Lateral meristem function

Diameter/girth growth

Types of lateral meristems

Vascular and Cork cambium

Type of apical meristem?

SAM

Type of apical meristem?

RAM

Label the meristem

Label the meristem

Primary meristems

Associated with primary growth

Types of primary meristem

• protoderm

• procambium

• ground meristem

Protoderm gives rise to

The epidermis

Ground meristem gives rise to

Ground tissue

Procambium gives rise to

Primary vascular tissue

Types of lateral meristems and what they give rise to

Vascular cambium: secondary vascular tissue

Cork cambium: periderm

Quiescent center

relatively inactive region in RAM, contains initials

SAM Zones

• Central Zones

• Peripheral Zones

• Rib Zones

Central Zone / CZ

large, slow division, provides new cells

Peripheral Zone / PZ

small, fast division, forms leaves + flowers

Rib Zone

Cells divide, pushes meristem up

• forms ground/vascular tissue

SAM organization (Zones, L1-3)

PCR

Polymerase Chain Reaction

Method to amplify DNA from a single strand to billions of copies

Kary Mullis

What do you need for PCR?

• Taq polymerase

• Template

• dNTPs / nucleotides

• Primers

• Mixing Tube

• Thermocycler/PCR machine

What type of gel was used in lab for PCR?

Agarose gel

What light was used to analyze PCR sample?

UV