Class XII Biology, Developement of seed and fruit, Apomixis and Polyembryony

1. DEVELOPMENT OF SEED, FRUIT,
APOMIXIS AND POLYEMBRYONY
BY-
SAVITA PATEL
PGT BIOLOGY

2. •Development of endosperm from PEN
•Development of embryo from zygote
•Development of seed from ovules
•Development of fruit from ovary

3. •SEED is the FINAL PRODUCT of fertilization.
• Described as FERTILIZED OVULE.

4. ALBUMINOUS
NON- ALBUMINOUS OR
EXALBUMINOUS
 Retain part of
endosperm in
mature seed.
 Examples
 Wheat
 Maize
 Castor etc.
 No residual
endosperm.
 Examples
 Pea
 Groundnut etc.

5. ALBUMINOUS SEED OF CASTOR AND
MAIZE
MAIZE

7. •Outer integument Testa or Seed Coat
•Inner integument Tegmen
• Micropyle Pore (for entry of O2 and
H2O)
• Funicle Stalk
•Hilum marks the point of attachment of
stalk.

10. As the seed matures, its water content is reduced,
it become relatively dry (10-15% moisture) and
general metabolic activity slows down.
The embryo may enter a state of inactivity called
dormancy.
Or
If favourable condition are available, they
germinate.

11.  Ability of seed to retain power of
germination under suitable
environmental conditions or after
completion of dormancy.
 It ranges from few days to years
 Few days – Oxalis
 2 to 5 years-Crop plants
 2000 years- Phoenix dactylifers
 10,000years-Lupinus arcticus
excavation of arctic tundra

12. POMOLOGY- Branch of horticulture that deals
with the study of fruits and their cultivation.
MANGO

13. TRUE FRUIT FALSE FRUIT
 Formed from ONLY
ovary.
 Examples- Grapes
etc.
 Formed from ovary
ALONGWITH other
acessory floral part.
 Example
 Apple and Fig
thalamus also
contributes to fruit
formation.
 Strawberry

16.  Production of seed
without
fertilisation.
 This mechanism
produces clones,
hence can be
considered as a
form of asexual
reproduction.
 MIMICS sexual
reproduction.

17. 1. Formation of embryo directly from diploid
sporophytic cell (nucellus or integument) of
ovule- ADVENTIVE EMBRYONY
2. Diploid egg cell is formed without meiosis i.e
reduction division and develops into embryo
without fertilisation.
Example- some species of Citrus and Mango

19. 1. Simple polyembrony- it is due to fertilization of
more than one egg cell in an ovule.
Example- Citrus
2. Cleavage polyembrony- it develops due to
splitting of the proembryo into two or more parts.
Example – Pinus, Orchid etc.
3. Adventive polyembryony- formation of additional
embryos from different parts of ovules such as
synergids, antipodals, nucellus, integument etc.
Example- Citrus, Opuntia, Mango

21. BENEFIT- Better quality.
PROBLEM- Seeds have to be produced every
year because if the seeds collected from hybrid
seeds are sown, the plant in the progeny will
seggregate and do not maintain hybrid
characters. Hence, become Expensive for
farmers.
SOLUTION- production of apomictic seeds in
hybrids can solve this problem as there will be
no seggregation of characters in the hybrid
progeny.