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Title: http://plantsinmotion.bio.indiana.edu/plantmotion/flowers/flower.html


1
Today Plant Reproduction W Genetic
Engineering of Plants
http//plantsinmotion.bio.indiana.edu/plantmotion/
flowers/flower.html
2
Fig 29.7
3
Seeds and pollen allow seed plants to reproduce
without water
Fig 30.2
4
Fig 38.4
Animal pollinators move pollen from one plant to
another
5
Fig 38.4
Plants reproduce, reward animals with sugar
6
Fig 38.2
a typical flower
7
Fig 38.2
Angiosperm Life Cycle
8
Fig 38.5
Each pollen grain has 3 nuclei, two sperm and one
for the pollen tube
N
N
N
9
Fig 38.5
Each pollen grain has 3 nuclei, two sperm and one
for the pollen tube
sperm
N
N
tube nuclei
N
10
Pollen tubes can grow quite long
corn stigma
corn seeds
11
The pollen tube grows to the egg and the sperm
fuse with the egg zygote and polar nuclei
endosperm
Fig 38.5
12
Fig 38.7
The zygote then develops into an embryo
surrounded by the endosperm and seed coat the
seed
13
Fig 38.8
The seed must contain enough nutrients to nourish
the embryo until it can begin photosynthesis
14
Seed size is a good indicator of how much energy
is stored to support early seedling growth.
15
Which seed likely requires light to germinate?
16
Fig 38.11
Seed dispersal can be by wind or often also by
animal
17
Fig 38.10
Fruits Animals can get nutrients to disperse
seeds
18
Fig 38.9
Seed Germination...
19
Capsaicin is a deterrent to seed eating mammals
20
Capsaicin is a deterrent to seed eating mammals
21
Is this plant reproducing sexually?
22
Problem of Inbreeding
  • Close relatives have a higher probability of
    carrying the same genetic defects
  • Decreases genetic diversity

see pg 813 and/or http//users.rcn.com/jkimball.ma
.ultranet/BiologyPages/S/SelfIncompatibilty.html
23
How do plants avoid inbreeding?Some plants, like
humans, separate the sexes--i.e., some plants
have only male flowers and others only female
flowers.
male plant
female plant
Fig 38.13
24
Some plants physically separate the anthers and
stigmas
Fig38.13
25
Some plants separate the anthers and stigmas
26
How do plants avoid inbreeding?
  • Some plants, like humans, separate the
    sexes--i.e., some plants have only male flowers
    and others only female flowers.
  • Some plants separate the anthers and stigmas.
  • Some plants have a cellular mechanism for
    avoiding inbreeding self-incompatibility

see pg 813
27
What is self-incompatibility?
  • Plants, like animals have the ability to
    distinguish self tissue from non-self tissue.
  • In humans, generally non-self tissue is rejected,
    so tissue transplants can be a problem.
  • In some plants self-pollen is rejected(
    self-incompatibility), and only non-self pollen
    is allowed to fertilize the eggs.

see pg 813
28
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29
Some signaling steps are known
  • This SI method requires that a factor from the
    pollen recognizes a factor from the stigma

see pg 813
30
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31
In sporophytic SI the reaction happens on the
stigma surface
  • If the male factor from pollen is recognized as
    self by the female factor on the stigma surface,
    then this recognition induces the stigma to
    secrete a substance that prevents the pollen from
    germinating.
  • the substance secreted by the stigma that
    inhibits self-pollen from germinating is unknown.

see pg 813
32
Only pollen from different plants can germinate
see pg 813
33
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34
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35
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36
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37
Self-incompatibility
  • Self-incompatibility (SI) is a method by which
    some plants avoid inbreeding
  • The two main mechanisms of SI are different from
    one another one stops the pollen on the surface,
    the other stops the pollen in the style.
  • Both methods require that a factor from the
    pollen recognize a female factor made by the
    flower, and in both methods this recognition
    initiates the SI reaction.

see pg 813
38
Fig 38.2
Angiosperm Life Cycle
39
Evolution does not always go forwardSome
angiosperms disperse pollen by wind
Fig38.4
40
Today Plant Reproduction W Genetic
Engineering of Plants
http//plantsinmotion.bio.indiana.edu/plantmotion/
flowers/flower.html
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