4. Endosperm development_3.pptx with basic terminalogies

Development of endosperm

1. Endosperm development Endosperm development generally precedes embryo development The fate of endosperm depends upon the species Beans, cotton or Brassicas Castor bean, tomato, carrot Cereal grains

2. Morphological variation of endosperms T o b ac c o E nd os p erm Embryo Most dicots: large cotyledons, small endosperms. Carrot seed

3. Types of endosperm formation Nuclear/non-cellular type: Free nuclear division gives rise to many nuclei and walls may or not form e.g., most of monocots and some dicots Cellular type: Cell walls form immediately after the first nuclear division and continue to do so as the endosperm grows e.g., most of dicots and some monocots Helobial type: regarded as intermediate restricted to few monocots

4. Developmental domains T r a n s f e r c e l l s Embryo surrounding regions (ESR) 3. Aleurone layer cells 4. Starchy endosperm cells M a i z e Ba r l e y

5. Endos p erm de v e l o p m en t Begin with the fertilized polar nuclei Triploid M i c r o p y l e A n t ip o d al c ell s P o l a r nu c l e i S yn e r g id s Double fertilization E g g M a t u r e o vu l e P o lle n tube

6. The cereal endosperm coenocyte

7. Cellularization of the Endosperm Coenocyte

8. Endosperm development in dicots Endosperm development in dicots is ephemeral in many species T w o vi ew s a b ou t e v ol uti o n o f endospe r m Endosperm is derived from a primitive embryo Endosperm is thought to be comparable with megagametophyte

9. The Arabidopsis endosperm coenocyte