Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 14: Development and Morphogenesis (Environmental Complexity (Touch…
Chapter 14: Development and Morphogenesis
Environmental Complexity
Light
provides two important type of info
direction or more precisely
gradient of light
duration of light
time of year
Gravity
selectively advantageous for many cell
to orient themselves
respect direction
Touch
plants do not move around
frequently grow against bojects
respond contact
Temperature
fluctuates in predictable pattern
daily
yearly axis
Water
prerequisite for life
does not act like a signal in the way other factors
Pests and Damage
plant must detect when they being attacked by
pests such as
bacteria
fungi
insects
digestive enzymes
Responding to Environmental Stimuli
Tropic Responses
growth response oriented with regard to stimulus
plagiotropism
growth at angle
thigomotropism
touch is stimulus
chemotropism
pollen tubes for flowering plant suspect
growing a long
probably from synergids
differential growth
contact side slowing
opposite side accelerating
both
Nastic Responses
stereotyped nongrowth
not oriented with regard to stimulus
diurnal
active during daylight
nocturnal
active at night
photonastic
opening and closing in same manner
light given artificially from
west
northsouth
above
below
sleep movement
blade elevated in the day
lowered at night
Morphogenic Responses
morphogenetic response
change "quality" of plant
Taxis
cell swim toward
away from stimulus
Communication within the Plant
Perception and Transduction
statocytes
root caps
have large starch granules
statoliths
sink in response to gravity
two important factors in preception&transduction
presentation time
length of time the stimulus present for perceptive cells
to react
complete transduction
threshold
level of stimulus must present during presentation time to cause
perception
transduction
all-or-none response
after the threshold
present time requirement are met
stimulus not long important
dosage-dependent responses
amount or duration of stimulus effect
Chemical Messengers
all plant by slow mechanism
transport of hormones through plant
hormones
organic chemicals produced in one part of plant
then transported to other
Signal Amplification Cascades
thousands of messenger molecules
not just original
chances are very high will enter nucleus
encounter proper genes quickly
Activation and Inhibition of Shoots by Auxin
Cell Elongation
in young cell internodes below apical meristem
auxin triggers cell elongation
Apical Dominance
result being each shoot tip has only one
apically produced auxin induces dormancy
in axillary buds
Differentiation of Vascular Tissues
third site of response t auxin produced in shoot tip
response is cell division
and morphogenesis
Interactions of Hormones in Shoots
apical dominance absence of auxin
interplay of two or three hormones
Hormones as Signals of Environmental Factors
Leaf Abscission
normal growth of shoot
root result in
large flows of auxin
cytokinin
environmental factor influenece
Tropisms
blue-light responses
blue-light stimulates other aspects of plant development
coleoptile
shows strong positive phototropic
oat seed have outermost protective leaf
oat coleoptiles are organ studied
Flowering
Ripeness to Flower
juvenile phase
plants are incapable induced to flower
adult phase
sensitive to floral stimuli
phage change
conversion from juvenile to adult
Photoperiodic Induction to Flower
photoperiod
transition to flowering is triggered
short-day plants
day are short
spring or fall
long-day plants
days are long
summer
day-neutral plants
do not respond to day length
phytochrome
detects the presence
absence of light
critical night length
varies from species to species
Endogenous Rhythms and Flowering
endogenous rhythms
metabolism cycle repeatedly between two states
cycle controlled by internal factor
negative feedback loop
clock is poorly understood
entrain
reset the rhythm
exactly 24 hrs long
circadian rhythm
period approximately 24 hrs long
ABC Model of Flower Organization
ABC model
most flowers can explain by hypothesis
homeotic mutation
organ develop in unexpected site
Concepts
morphogenesis
generation of shape of the plant
various organs
differentiation
increase some cell become different from each other
polarity
formation
root
shoot axis
pattern establishment mechanism
cell location relative to epidermis cell
