Title: http://plantsinmotion.bio.indiana.edu/plantmotion/flowers/flower.html
1Today Plant Reproduction W Genetic
Engineering of Plants
http//plantsinmotion.bio.indiana.edu/plantmotion/
flowers/flower.html
2Fig 29.7
3Seeds and pollen allow seed plants to reproduce
without water
Fig 30.2
4Fig 38.4
Animal pollinators move pollen from one plant to
another
5Fig 38.4
Plants reproduce, reward animals with sugar
6Fig 38.2
a typical flower
7Fig 38.2
Angiosperm Life Cycle
8Fig 38.5
Each pollen grain has 3 nuclei, two sperm and one
for the pollen tube
N
N
N
9Fig 38.5
Each pollen grain has 3 nuclei, two sperm and one
for the pollen tube
sperm
N
N
tube nuclei
N
10Pollen tubes can grow quite long
corn stigma
corn seeds
11The pollen tube grows to the egg and the sperm
fuse with the egg zygote and polar nuclei
endosperm
Fig 38.5
12Fig 38.7
The zygote then develops into an embryo
surrounded by the endosperm and seed coat the
seed
13Fig 38.8
The seed must contain enough nutrients to nourish
the embryo until it can begin photosynthesis
14Seed size is a good indicator of how much energy
is stored to support early seedling growth.
15Which seed likely requires light to germinate?
16Fig 38.11
Seed dispersal can be by wind or often also by
animal
17Fig 38.10
Fruits Animals can get nutrients to disperse
seeds
18Fig 38.9
Seed Germination...
19Capsaicin is a deterrent to seed eating mammals
20Capsaicin is a deterrent to seed eating mammals
21Is this plant reproducing sexually?
22Problem 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
23How 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
24Some plants physically separate the anthers and
stigmas
Fig38.13
25Some plants separate the anthers and stigmas
26How 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
27What 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(No Transcript)
29Some signaling steps are known
- This SI method requires that a factor from the
pollen recognizes a factor from the stigma
see pg 813
30(No Transcript)
31In 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
32Only pollen from different plants can germinate
see pg 813
33(No Transcript)
34(No Transcript)
35(No Transcript)
36(No Transcript)
37Self-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
38Fig 38.2
Angiosperm Life Cycle
39Evolution does not always go forwardSome
angiosperms disperse pollen by wind
Fig38.4
40Today Plant Reproduction W Genetic
Engineering of Plants
http//plantsinmotion.bio.indiana.edu/plantmotion/
flowers/flower.html