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BIOL 225 PLANT FINAL NOTES FORM AND FUNCTION OF ORGANISMS Concordia University
- Course
- BIOL 225
- Institution
- Concordia University ( )
BIOL 225 PLANT FINAL NOTES FORM AND FUNCTION OF ORGANISMS Concordia University
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BIOL 225 PLANT FINAL NOTES FORM ANDFUNCTION OF ORGANISMS Concordia University
PLANT LECTURE 9
Plant Development
- Cells form specialized tissues, organs, and organisms through the process of development
- Plant development differs from animal development:
Plants continue to grow and develop throughout their lives (Continuous development)
- Plants have tremendous developmental plasticity (regeneration/de-differentiation)
- Plant cells do not migrate
“This ability to alter form in response to a local environment conditions is called developmental
plasticity.
The three overlapping processes in development: growth, morphogenesis, and cell differentiation.
Morphogenesis: the process that gives tissue, organ or organism its shape and determines the position
of the cell types.
Cell differentiation: the process by which cells become different from one another.”
Asymmetric cell division:
cell division (mitosis) that creates two daughter cells with distinct cell fates. e.g. human stem cells,
stomatal development
Organ formation occurs mostly after seed germination.
“ Although the plane of cell division does not determine the shape of plant organs, the symmetry of cell
division – the distribution of cytoplasm between daughter cells – is important in determining cell fate.
Asymmetrical cell division, in which one daughter cell receives more cytoplasm than the other during
mitosis, usually signals a key event in development. For example, the formation of guard cells typicaly
involve both an asymmetrical cell division and a change in the plane of cell division. An epidermal cell
divides asymmetrically, forming a large cell that remains an unspecialized epidermal cell and a small cell
that become the guard cell “mother cell”. Guard cells form when this small mother cell divides in a
plane perpendicular to the first division.”
,Developmental plasticity describes the effect of the environment on development.
,Meristems
- Plant development is the product of meristems
- Growing tips (apices) of the plant
- Contain continuously dividing cell populations
- All plants have at least one form of apical meristem, most have two:
Root apical meristem (RAM)
Shoot apical meristem (SAM)
- Provide all the cells of the
development The Shoot Apical Meristem
(SAM)
- Must be established and maintained after germination
- Organ formation occurs mostly after seed germination
- Generate new organs and maintain stem cell reservoir for future organ formation
<Layer structure>
- L1: the outermost layer, differentiates into epidermis
- L2: the second layer, differentiates into subepidermis, cortex
- L3: the internal layer, differentiates into vasculature,
pith Model Organisms: revolutionizing the study of plants
- New techniques and model organisms are
catalyzing explosive progress in our understanding
of plants
- The small flowering plant Arabidopsis is used as a
model organism
- Studying the genes and biochemical pathways of Arabidopsis will provide insights into
plant development and reproduction
WHY DO WE WORK WITH ARABIDOPSIS?
- Arabidopsis is the most commonly studied model plant for molecular genetics
- Arabidopsis is small
- Easy cultivation in restricted space
- Amenable to selection under laboratory conditions
- The Arabidopsis genome is small
- Arabidopsis has strong genetic tools (sequenced genome, mutant
libraries) Arabidopsis has 25,498 genes
- Arabidopsis can self or cross pollinate, it is also fast and easy to grow (short life cycle, self
pollinates)
, After stratification plates are moved to a growth room.
Transferring seedlings
Cover and move to growth chamber. ↓
Arabidopsis can be transformed
Arabidopsis can easily be transformed by
introducing foreign DNA via genetically altered
bacteria.
It has the same developmental stages as all other flowering plants.
The life cycle of a flowering plant
- The life cycle of a flowering plant begins with gametogenesis, gamete formation.
- Fertilization occurs when sperm and egg combine in a womb-like ovule inside the
protective female reproductive structure of a flower.
- Development continues inside the ovule with embryogenesis.
In many plants embryogenesis ends with the maturation of the ovule into a seed, which
contains the dormant embryo and a supply of nutrients and is surrounded by a protective coat.
- When conditions are favourable, the seed undergoes germination, resuming growth to form
a seedling.
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