Week 13 L2: Plant Development General Principles Flashcards
What is the architecture of a plant?
How a plant is put together
form number and arrangement of plant body parts
How does architecture vary?
within and between species
How do cells achieve their specialised fates?
differential gene expression underlies development
genes are expressed differently; how where and when genes are expressed.
What 2 factors can dictate gene expression?
genetics and environment
How do animals grow and develop?
develop most of their bodies after embryogenesis
Plants all start off looking similar but eventually differentiate form one another
post-embryonically. growth and organogenesis.
What gives rise to the complete adult organism?
pocket of stem cells in the shoot and root tips
What do seedling emerge with?
embryonic stem (hypocotyl)
embryonic root
embryonic leaves (cotyledons)
Shoot and root tips
and a sense of polarity
What gives plants the initial photosynthesis?
embryonic leaves on the apical axis
called cotyledons
How many cells give rise to arial development?
35 stem cells in the shoot tip
What are the cells called that can divide and differentiate in the shoot and root tip?
meristems
What are meristems?
regions of unspecialised cells in plants that are capable of cell division
Packet of dividing stem cells which fuel the growing plant body
Where are meristems found?
root and shoot tips and between xylem and phloem
What do the meristems produce?
phytomers a module
Do meristems continually and sequentially produce phytomers?
YES
What is a phytomer?
one of the individual structural units that in serial arrangement make up the body of a plant a bud-bearing node is a typical phytomer.
What are the components of a phytomer?
lateral organ
axillary bud
internode
node
Can plants of the same species have different number of modules?
YES, plants which are genetically identical can have an intermediate amount of modules depending on their environmental control e.g. sunlight
What are the traits that can develop according to enviroment?
Plasticity
What is an example of plasticity/plastic response?
A plant maximising its leaf surface area in shade to maximise sun exposure and photosynthesis
Why is plasticity important for plants?
they cant move, so need to be able to adapt to environment.
Plant’s offspring can be not near their mother so cannot determine its exact environment so need plasticity.
Is plasticity genetically determined?
YES, the plant species has to have the ability to change its phenotype. e.g some plants cannot adapt to light conditions
Within a species there will be specific aspect of that development that is plastic
What is it called when genes are unable to be plastic in a certain environment?
CANALISED
What is an example of a canalised trait?
Arabadopsis always has 4 petals no matter the environment
very little plasticity in the floral programme
Why is flowering usually canalised?
because the flowers architecture is really beneficial to the plant.
It is usually co-evolved with a certain pollinator and you don’t want to suddenly change the architecture and plant will not receive the correct pollinator.
Do plants always canalise the same?
NO, it depends on the species
What is the prymordia?
earliest stages of development
called primordial cells
e.g. buds on a stem blossom to flowers
When are meristems formed?
during embryogenesis and then produce lateral structures
What are lateral structures?
leaves and branches
What is the purpose of meristem zones?
predict how cells within them are going to behave
What are the 3 zones of the meristem at the shoot tip?
central zone
peripheral zone
rib meristem
What are cells like in the central zone of the meristem?
pool of undifferentiated stem cells. cells divide slowly
What are cells like in the peripheral zone?
proliferate faster and differentiate into lateral organs.
What are cells in the rib meristem doing?
proliferate and differentiate into the stem in dicots. stem art of the phytomer
How do cells enter the peripheral zone in the meristem?
As cells divide they push the outer cels out towards the peripheral zone.
They are pushed into position by division and cell growth.
What determines the cells fate in plants?
their position
