-
110/8/2010 [email protected]
1
Reproduksi
Seksual pd
Angiospermae
10/8/2010 [email protected]
2
Alat Reproduksi Angiospermae
Stamen / Benang Sari Setiap stamen terdiri atas anthera, yang
mengandung
mikrosporangia dan didukung oleh filament
Meiosis pada sel induk mikrospora yang diploid di dalam antera
menghasilkan empat mikrospora haploid.
Masing masing mikrospora akan berkembang menjadi serbuk sari
dengan dua sel, kedua sel tersebut adalah :
Sel buluh serbuk dan Sel generatif
Karpel Karpel terdiri atas stigma, stylus dan ovarium. Semua
bagian ini
membentuk pistilum.
The megasporangia, disebut ovul, berkembang di dalam ovarium.
Meiosis pada sel induk megaspora di dalam setiap ovul
menghasilkan 4 sel haploid : 1 sel megaspora yang besar, dan 3
sel kecil yang disintegrasi.
-
210/8/2010 [email protected]
3
Development of the megaspore
The nucleus of the megaspore undergoes 3 successive mitotic
divisions. The 8 nuclei that result are distributed and partitioned
off by cell walls to form the embryo sac. This is the mature female
gametophyte generation.
The egg cell will start the new sporophyte generation if it is
fertilized.
The large central cell, which in most angiosperms contains two
polar nuclei, will after its fertilization develop into the
endosperm of the seed.
10/8/2010 [email protected]
4
Pollinasi
When a pollen grain reaches the stigma, it germinates into a
pollen tube. The generative nucleus divides by mitosis forming 2
sperm nuclei. These, along with the tube nucleus, migrate down the
pollen tube as it grows through the style and into the ovule
chamber. The pollen tube with its contents makes up the mature male
gametophyte generation.
-
310/8/2010 [email protected]
5
Double Fertilization
The pollen tube enters the ovule through the micropyle and
ruptures.
One sperm nucleus fuses with the egg forming the diploid
zygote.
The other sperm nucleus fuses with the polar nuclei forming the
endosperm nucleus. Most angiosperms have two polar nuclei so the
endosperm is triploid (3n).
The tube nucleus disintegrates.
10/8/2010 [email protected]
6
-
410/8/2010 [email protected]
7
Ovum (n)
Penyerbukan
Zygota (2n)
:
Antipoda (n)
Inti kandungLembaga skunder (2n)
Inti kandungLembaga skunder (2n)
Sperma II (n)
Sperma I (n)
Embryo (2n)
Buluh serbuk
Serbuk sari
Benang sari
Sel kandung lembaga
Bakal biji
Putik
Bunga
Endosperm (3n)
Gambar 3 : Pembuahan ganda
10/8/2010 [email protected]
8
Buah (hasil pembuahan) Buah partenokarpi
Bakal biji
Ovum x sperma Ovarium Buah tak berbiji
Zygota Giberelin
(dihasilkan bakal biji yang tak dibuahi)
Embryo
Menghasilkan
Giberelin
Ovarium Buah berbiji
-
510/8/2010 [email protected]
9
FISIOLOGI
BIJI
10/8/2010 [email protected]
10
Biji
Mengandung embrio tumbuhan yang sedang berkembang dalam selubung
protektif yang disebut testa
Biji terbentuk dari bakal biji (ovula) yang dibuahi di dalam
ovarium
Ovarium dengan biji di dalamnya akan menjadi buah.
-
610/8/2010 [email protected]
11
After double fertilization, each ovule develops into a seed,
which consists of
a plumule, made up of two embryonic leaves, which will become
the first true leaves of the
seedling, and
a terminal (apical) bud. The terminal bud contains the meristem
at which later growth of the stem takes place.
One or two cotyledons which store food that will be used by the
germinating seedling.
Angiosperms that produce seeds with two cotyledons are called
dicots. Examples: beans, squashes, Arabidopsis
Angiosperms whose seeds contain only a single cotyledon are
monocots. Examples: corn and other grasses.
The hypocotyl and radicle, which will grow into the part of the
stem below the first node ("hypocotyl" = below the cotyledons) and
primary root respectively.
A pair of protective seed coats derived from the walls of he
ovule.
10/8/2010 [email protected]
12
-
710/8/2010 [email protected]
13
The food in the cotyledons is derived from the endosperm which,
in turn, received it from the parent sporophyte. In many
angiosperms (e.g., beans), when the seeds are mature, the endosperm
has been totally consumed and its food transferred to the
cotyledons. In others (some dicots and all monocots), the endosperm
persists in the mature seed.
The seed is thus a dormant embryo sporophyte with stored food
and protective coats. Its two functions are dispersal of the
species to new locations (aided in angiosperms
by the fruit)
survival of the species during unfavorable climatic periods
(e.g., winter). "Annual" plants (e.g., beans, cereal grains, many
weeds) can survive freezing only as seeds. When the parents die in
the fall, the seeds remain alive - though dormant- over the winter.
When conditions are once more favorable, germination occurs and a
new generation of plants develops.
10/8/2010 [email protected]
14
Seed:
Seed Coat
Embryo
Storage Tissue (Endosperm)
Seed Hormones
CK-CytoKinin
cell division
GA-Gibberellic Acid
cell expansion
AbA-Abscisic Acid
dormancy
-
810/8/2010 [email protected]
15
The Three Fundamental Parts
of a Seed
1. Seed Coat
2. Embryo
3. Storage
Tissue
1. Leaf
2. Stem
3. Root
of an Embryo
10/8/2010 [email protected]
16
Parts of a Seed External seed coat or testa Developing plant
embryo Stored food called endosperm Seeds may be in one part
(monocot)
or two parts (dicots)
MONOCOT
DICOT
-
910/8/2010 [email protected]
17
Parts of a Seed
10/8/2010 [email protected]
18
Gymnosperm Seed
A single fertilization produces the diploid (2n) embryo
The food source is the haploid megagametophyte
-
10
10/8/2010 [email protected]
19
Dicot vs. monocot seed
Dicot has two cotyledons (like bean)
Endosperm (food) is kept in the cotyledon
Monocot has one cotyledon which
absorbs the endosperm
tissue during
germination (corn)
10/8/2010 [email protected]
20
Kulit buah bersatu dengan kulit biji
Posisi Endosperm
Posisi embryo
Biji utuh
Kulit biji
mikropil
hilum
Biji utuh
endosperm
endosperm
remains of style
Kulit buah dan kulit biji yg bersatu
coleoptil
plumula
radikula
coleorhiza
A. Irisan membujur
radikula
plumula
kotyledon
A. Irisan membujur
embryo
Gambar 5. Struktur BijiA. Biji jagung
B. Biji kacang kedelai
-
11
10/8/2010 [email protected]
21
Growth of the shoot
Photosynthesis and Storage
Lifting the shoot above the soil
Producing lateral roots
Penetrating the soil
These functions. occur in this part of the embryo
Shoot apex
Cotyledon (leaf)
Hypocotyl (stem)
Radicle (root)
Root apex
10/8/2010 [email protected]
22
-
12
10/8/2010 [email protected]
23http://www.biologie.uni-hamburg.de/b-online/ibc99/koning/seedgerm.html
10/8/2010 [email protected]
24
PENYEBARAN
BIJI
-
13
10/8/2010 [email protected]
25
Fruits serve many functions
in the plant world
Food source for the germinating seedling
Plants need to get around. They do this with their fruits.
Adaptations for dispersal
10/8/2010 [email protected]
26
Fruit and Seed Dispersal
The main function of the fruit is to disperse the seeds
Dispersal is important because 1. It spreads the progeny in
order to
colonize new environments
2. Reduces competition for resources with parents
3. Reduces the chances of predators destroying all of the plants
yearly seed production
-
14
10/8/2010 [email protected]
27
Types of Seed Dispersal
Three types of seed dispersal:
1. Self dispersal
Mechanical Ejection of Seeds
2. Physical Carrier Dispersal
Wind dispersal
Water dispersal
3. Biological Carrier Dispersal
Animal dispersal
10/8/2010 [email protected]
28
A. Self dispersal
Plants disperse their seeds by forceful ejection explosive
fruits!
Witch hazel, squirting cucumber (jet propulsion)
-
15
10/8/2010 [email protected]
29
Mechanical
Ejection Geranium fruit
exploding
Legume
(Pea seeds)
A
combination
of ejection
and
attraction
10/8/2010 [email protected]
30
Mechanical
Ejection
Impatiens Fruit Exploding
-
16
10/8/2010 [email protected]
31
Self dispersal The peanut plant sows
(buries) its own seeds!
Geocarpic: carpel grows inside the earth (soil)
10/8/2010 [email protected]
32
B. Wind dispersal Small and Lightweight seeds.
Fruit and seeds may have special devices for wind dispersal
Plumes catch wind currents: Dandelion
Trees take advantage of their great heights for wind dispersal.
Fruits with wings are used to slow the descent to land: maple, ash
fruit
-
17
10/8/2010 [email protected]
33
10/8/2010 [email protected]
34
-
18
10/8/2010 [email protected]
35
C. Water Dispersal Fruits and/or seeds use flotation
devices to travel by water (in rivers,
oceans, etc.)
Fruit may have air spaces and corky floats: for example
coconut
10/8/2010 [email protected]
36
-
19
10/8/2010 [email protected]
37
Coconuts are Water Dispersed
10/8/2010 [email protected]
38
D. Animal dispersal Plants have interaction with animals to
accomplish seed dispersal
Many plants depend on animals for seed dispersal; they may offer
a nutritional reward
Animals learn to recognize ripened fruit colors
Fleshy fruits eaten and dispersed with feces
-
20
10/8/2010 [email protected]
39
Animal dispersal Some dry fruit attach and cling to
animals
(they hitchhike on the animals)
Some have Velcro-like hooks that cling to animal fur (burdock,
cockleburs)
Others have sticky substances that stick to host (mistletoe)
Oils attract ants.
10/8/2010 [email protected]
40
Animal Dispersal
Long distance dispersal by birds:
fruits and seeds trapped in the mud on their feet
Seeds released in excrement
Animals eat fruit, the seeds pass through the digestive
tract.
Scarification by digestive enzymes is necessary for
germination
-
21
10/8/2010 [email protected]
41
10/8/2010 [email protected]
42
How Ripened Fruits
Attract Animals
1. Softer, easier to digest
2. More fragrant
3. Brightly colored
4. Increase in sugar content is a source of carbohydrates
(reward)
-
22
10/8/2010 [email protected]
43
Further Study on Seed
Dispersal What carries the dandelion seeds for miles?
What feature of trees gives them a particular advantage when
dispersing seeds by air?
How does the squirting cucumber disperse its seeds?
Although plants use wind and water, what do most plants use as
carriers for their seeds?
Blackberries on a tree do not ripen simultaneously, why?
What plant do elephants help to disperse? How do they do it?
What percentage of these seeds
germinate in elephant dung? Why?
10/8/2010 [email protected]
44
Pithecellobium oblongum fruit shows some of the traits often
found in the
fruits of bird-dispersed seeds
-
23
10/8/2010 [email protected]
45
Fruits and Dispersal Fruits remain
distasteful to most animals (including humans) until they are
ripe
This ensures that the fruit will not be eaten until the seeds
are mature