Flowering Plants

Domain Eukarya

Kingdom Plantae

Phylum Anthophyta/Magnoliophyta

SYNGAMY

zygote

SporophyteGametophyte

sporangium

sporocytespores

gametangia

gametesgermination

mitosis

differentiation

mitosisgerminationmitosis

mitosis

1N 2N

differentiation

differentiation

differentiation

MEIOSIS

Life Cycle of Flowering Plants

The flowering plant is a multicellular diploid sporophyte.

The sporophyte encloses the multicellular haploid gametophyte.

The life history is thus sporic (diplohaplontic).

The gametes are oogamous but the sperm lack flagellae.

Gender expression has moved from gametophyte to sporophyte.

androecium

petal corolla

calyx

gynoecium

¢

™stigma

style

ovary

ovule

locule

filament

anther

sepal

pedicel

receptacle

carpel

stamen

completeperianth

flowerperfect

superior

flower hypogynous

pollen

Flower Organization-building a flower from bottom up

A flower is a short shoot (stem with leaves)The stem is represented by the receptacle with very short internodesThe leaves appear in four whorls

http://images.iasprr.org/lily/lpachy-m.jpg

Microsporogenesis: Prophase I of Meiosis

http://images.iasprr.org/lily/lepto.jpg

Microsporogenesis: Late Prophase I of Meiosis

http://images.iasprr.org/lily/meta-i.jpg

Microsporogenesis: Metaphase I of Meiosis

http://images.iasprr.org/lily/anaph.jpg

Microsporogenesis: Anaphase I of Meiosis

http://images.iasprr.org/lily/telo-i.jpg

Microsporogenesis: Telophase I of Meiosis

http://images.iasprr.org/lily/meta-ii.jpg

Microsporogenesis: Metaphase II and Anaphase II of Meiosis

http://images.iasprr.org/lily/telo-ii.jpg

Microsporogenesis: Telophase II of Meiosis

http://images.iasprr.org/lily/tetrad.jpg

Microsporogenesis: Meiosis complete (but prophase of mitosis)

http://images.iasprr.org/lily/microsp.jpg

Microsporogenesis: Completed, Separated Microspores (note prophase)

http://images.iasprr.org/lily/pollen2.jpg

Pollen Grain: Mitosis Makes Endosporic Microgametophyte

Tube Cell

Nucleus

Cytoplasm

Generative Cell

Nucleus

Cytoplasm

The tube cell digests a path from the stigma to the egg.

The generative cell follows the path to the egg, and divides to make two sperm cells. Both participate in syngamy.

Pollination: vector-assisted movement of the

pollen grain from the anther to the stigma.

Pollen Wall: Microspore Wall (allergenic?)

http://bilbo.bio.purdue.edu/~cjslab/pollen-tubes.jpg

Pollen Tube GrowthThe tube cell germinates through the pollen wall.The cell grows chemotropically toward the egg.The pollen tube must find the ovule’s micropyle.The generative cell slides along this tube.It divides by mitosis to form two sperm cells.

Megasporogenesis: taking place inside the ovule inside the ovary.

megasporocytemeiosis I meiosis II

4 megaspores3 disintegrate

functionalmegaspore

mitotic divisions without cytokinesis

cytokinesis

megagametophyte

egg

central cell

3 antipodals

2 synergids

http://botit.botany.wisc.edu/courses/img/Botany_130/Diversity/Angiosperms/Fertilization.jpg

1N egg + 1N sperm = 2N zygote

syngamy#1:

syngamy#2:

2 x 1N polar nuclei + 1N sperm = 3N primary endosperm cell

In Flowering Plants, syngamy is a double event:

spermnuclei

synergidsdisintegrating In this slide, plasmogamy has

already occurred…but what part of syngamy has not occurred yet?

karyogamy!

no miracle-gro, no compost!