Lecture 13: Plant Development Flashcards
what have plants ever done for us?
- cotton
- pills
- food
- oxygen
food, energy and water shortages are fuelled by
growing populations
plants aid earth how?
- use light as a sustainable energy source
- run on CO2 and produce oxygen
- require modest capital, start-up & maintenance, easily scalable
- produce wide range of useful products
- pleasing landscape
key stages of development in animals
- fertilisation (fusion of egg and sperm to give zygote)
- cleavage (division of cells to form blastula)
- gastrulation (formation of tissue layers & axis)
- organogenesis (formation of organs)
- Morphogenesis (mechanism of body shape formation)
plant cells are fused together by a
cell wall
the 3D form of a plant depends on the
previous number and orientations of cell division and the relative growth of the cells
the orientation of cell division and the relative growth of cells defines
both the overall form of the plant and the internal anatomy
how are plants like animals
- develop from a fertilised egg
- the zygote undergoes growth and division to form multi-cellular organism
- plant cells differentiate to take on specific function s
how are plants NOT like animals
-consist of cells are encased in a wall. They are immobile. Size and shape of the organism is determined by patterns of cell division and growth
-show extensive post-embryonic generation of form.
This is due to the maintenance of stem cell niches (meristems)
the adult forms of plants and animals consist of
repeated elements
in plants the repeated elements that form it are
not set down in the embryo, they’re formed by the shoot apical meristem
the meristem is
a highly dynamic structure generating form and pattern
_____ signals control positioning in the body
CHEMICAL
- Cells “know” they are in an organism by interpreting POSITIONAL INFORMATION
- positional inför
Positional information is given by___ what in plant so cell know where they are in an organism
given by the concentration of a MORPHOGEN
FRENCH FLAG MODEL
___ plays key role in many patterning processes in plants
AUXIN
Polar Auxin Transport (PAT )
- auxins are week acids. inside the cell is negative (IAA-)
- PIN protein (auxin export) leave & are protonated so = IAAH
- AUX1 (auxin import) IAAH enters and deprotonated to IAA- again
-one direction of movement
the pattern of auxin flux in the shoot meristem dictates where
leaf formation occurs
computation models of auxin transport mimic
natural patterns
three primary meristems in the roots are:
protoderm
ground meristem
procambium
description of root structure
bottom:
- Root cap
- quiescent center
- apical meristem surround quiescent centre
- zone of elongation
- zone of maturation with root hair.
- stele (middle)
- cortex
- epidermis
pattern of auxin flow is determined by
PIN transportes in the root leads to a local high auxin level which determines where the root stems cells form
the primary meristems define
the basic structure of the plant
plants vs animals in young and adult growth forms
- the mature plant form is vastly more complicated than the embryo
- i plants growth and development can occur over long time spans
plant development depend on the distribution of
secondary meristems (stem cell niches) throughout the plant
where are secondary meristems generated?
and what do 2nd meristems become?
primary apical meristem. Secondary meristems can be activated to form new structures, linking environment to form (distance from animals)
distribution of meristems throughout the plant enable it to
withstand & respond to serious damage
pattern of meristem activation determines
form. Plants develop geometric form by branching
meristems within the stem can become activated to
increase stem size (“cambium” meristems)
wood formation depends on
meristems.
2 types
–vascular cambium (inside)
–cork cambium (outside)
root contains numerous meristems:
- Pericycle (site of secondary meristems) [above root tip]
- primary meristem (closer to bottom)
the pericycle generates
new lateral roots which allow the plant to explore its environment. Activation of the pericycle links development to the environment
meristems can be cultures to..
…multiply & regenerate whole plants
transcription factors involved in meristem function can be used to
manipulate plant form
kalanchoe generates…
ectopic meristems along the edge of the leaf. Each meristem forms a bud which can generate a plant (asexual reproduction )
meristems contain…
the stem cells for the plant & produce cells from which the rest of the plant is made
meristems are distributed in one place in plants T/F
FALSE
activation of meristems can breath influence the final plant form T/F
TRUE
activation is often dependant on environmental triggers
molecular biology has led to the identification of genes required for meristem function T/F?
TRUE
