1. Megasporogenesis: taking place inside the ovule inside the ovary.
megasporocyte
4 megaspores
meiosis I
meiosis II
3 disintegrate
functional
megaspore
mitotic divisions without cytokinesis
megagametophyte
3 antipodals
central cell
egg
cytokinesis
2 synergids
Compare Fig Pg. 828 and Fig Pg. 832

2. Life Cycle of Flowering Plants
central cell
egg
SYNGAMY
zygote
Sporophyte
Gametophyte
sporangium
sporocyte
spores
gametangia
gametes
germination
mitosis
differentiation 1N 2N
MEIOSIS
embryo sac
ovule
antipodals
synergids
megasporocyte
The large plant is a sporophyte.
Its flower produces the sporangia; on the female side, the ovule of the carpel
The ovule contains a megasporocyte that divides by meiosis to make four megaspores
Three megaspores disintegrate.
The remaining megaspore cell divides by mitosis to make 8 nuclei.
Cytokinesis divides the 8 nuclei into seven cells of the megagametophyte (embryo sac)
The egg cell and the central cell are gametes that fuse with two sperm cells in syngamy
The ovule, with zygotic embryo and triploid endosperm, becomes a seed.

3. karyogamy! In Flowering Plants, syngamy is a double event: syngamy#2:
Compare Fig Pg. 832
In Flowering Plants, syngamy is a double event:
syngamy#2:
2 x 1N polar nuclei + 1N sperm
= 3N primary endosperm cell
sperm
nuclei
no miracle-grow, no compost!
1N egg + 1N sperm = 2N zygote
syngamy#1:
synergids
disintegrating
In this slide, plasmogamy has already occurred…but what part of syngamy has not occurred yet?
karyogamy!

4. How about Dicots? seed coat cells Cells to become storage tissue
Polar Nuclei
Sperm Nucleus
Syngamy => Endosperm 3N
Egg Cell
Sperm Nucleus
Egg Nucleus
Syngamy => Zygote 2N

5. These are globular embryos with suspensors.
suspensor cells
In Dicots (Capsella), the development lacks competition, but the sequence is similar.
These are globular embryos with suspensors.
Compare Fig Pg. 833
Compare Fig Pg. 471

6. Heart-shaped embryo with suspensor
Protoderm
Ground   meristem
Undeveloped?
Provascular
Heart-shaped embryo with suspensor
Compare Fig Pg. 833

7. Maturing embryo “torpedo”
Mature      embryo
Maturing embryo “torpedo”
Compare Fig Pg. 833

8. Capsella Seed:
Embryo
Seed Coat
Shoot Apex
Endosperm
Cotyledons - eudicot
Hypocotyl
Radicle
Root Apex
Micropyle

9. radicle penetrates seed coat
Lettuce Seed Germination
radicle penetrates seed coat
starch
hydrolysis
Seed Coat
shoot apex
sugar
-amylase
cotyledons
dicot
translation
Compare Fig Pg. 801
RNA
growth
red and white light stimulate germination
transcription
Embryo
DNA
radicle apex
phytochrome
photoreversibility
660 nm
Pfr Pr
water
photoactivation
730 nm
imbibition
dark