1. Plant Reproduction
Biotechnology II

2. Essential Questions How do angiosperms reproduce?
What defines a model organism?

3. Angiosperms Plants that produce flowers
Angiosperms – most diverse group in plant kingdom. Why?
Evolved flowers and fruits. This allowed
Increased successful mating of stationary organisms
Flowers protect the egg and improved odds of fertilization
Allowed plants that were considerable distance to mate through pollinators
Fruit that surrounds the seeds –aided in dispersal with the help of animals

4. Development of flower-Why?
Being terrestrial and lack locomotion –poses several problems:
Gametes delicate cells.
To achieve cross-fertilization, two gametes must reach each other safely.
Must have a mechanism for dispersal
Must be far enough away from parent so not to compete for light, water, and soil minerals.

5. Types of flowers
Perfect flower – have both microsporangia (male) and megasporangia (female)
Imperfect flower – have either microsporangia (male) or megasporangia (female)

6. Development of the flower
Develop from flower buds- each bud has 4 concentric whorl of tissues
Whorl of sepals – calyx
Whorl of petals - corolla
Stamens – where microsporangia(sperm) form
Carpels – where megasporangia (egg) form

7. Anatomy of the Flower

8. Sexual Reproduction Pollen (contains sperm)is released from the anther
Carried to the carpel, female reproductive organ
Attaches to stigma
Pollen germinates – forms pollen tube
Pollen tube carries sperm to the egg in the ovule

9. Sexual Reproduction
Animation of pollen germination and pollen tube growth

10. Pollination Pollen tube when it reaches ovule –releases the sperm
Sperm nucleus and Egg nucleus combine to become the zygote
Zygote divides and forms the embryo

11. Self-incompatibility
Many angiosperms have mechanisms that prevent self-fertilization by rejecting its own pollen
Prevent the pollen from germinating
Promote genetic variation

12. Seed Once fertilized, each ovule develops into the seed
A plumule – made up of two embryonic leaves, which become the first true leaves of the seedlings.
Cotyledons
Dicot – two cotyledons – ex. bean seed
Monocot-one cotyledon- ex. corn seed

13. Seed Radicle – primary root
Hypocotyl- part of the stem below the first node where the plumule is attached

14. Fruits Develop from the ovary wall
Seeds mature release hormone auxin –stimulates the ovary wall to develop into fruit

15. Plant Breeding Also known as artificial selection
Takes advantage of sexual reproduction in plants
Collect pollen with desired phenotypic traits
Pollinate flowers on neighboring plants
Majority of Agriculture crops grown today were developed using artificial selection

16. Brassica rapa Belong to the mustard family
Same family as cabbage, cauliflower, broccoli, and arabidopsis

17. Economic Importance
Important economically as oilseed crop and animal fodder
Crucifer oil, known as rapeseed oil, is the third most commonly traded vegetable oil in the world
Rapeseed contains 40% oil-released when the seed is pressed
Remaining seed meal is high in protein and used in animal feed and nitrogen fertilizer

18. Development of Rapid Cycling Brassica
Wanted to incorporate efficiently traits of economic important, such as disease and pest resistance
Needed an ideal plant type to speed research in genetics and plant breeding
Began to breed Brassica rapa

19. Breed plants for Selective Traits
Traits included
Minimum time from planting to flowering
Rapid seed germination
Absence of seed dormancy
Small plant size
High female fertility – ovules once fertilized would develop into seeds rather than abort

20. Final Product
Through this plant breeding created a plant with a rapid life cycle
Plant has an average life cycle of 35 days compared to a normal 6 to 12 month life cycle

21. Life Cycle of Brassica

22. Other traits that make it ideal as a model organism
Small in size; grow many in a small space
Developed mutants for studying the growth and development of the plant

23. Lab Activity
Use the model plant, Brassica Rapa, to monitor seed germination

24. Answer the following questions
What was the evolutionary significance of flowers?
What organs in the flower are the male (sperm) gamete and female (egg) gamete found, respectively
Explain the process by which the pollen fertilizes the egg.
What does it mean to be self-incompatible?
What is the economic importance of Brassica rapa?
What is Brassica rapa considered a model organism for studying plants?
Read pp ; answer questions on p. 289 and 292.