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Plant Development and Morphogenesis plant-growth-stages-plant-development…
Plant Development and Morphogenesis
Environmental Complexities
Touch
Temperature
suitable temperature is required for plant to grow
Gravity
advantageous for many plants
orient themselves or their parts with respect to the direction of gravity
Water
one of the most important component for plant development
in case of water scarcity, the plant triggers specific responses
Light
light gradient: allows plant to grow or orient toward a bright region
important factor for photosynthesis
duration of light gives information about the time of the year
Pests and Damage
Responding to Environmental Stimuli
Nastic Responses
based on changes on turgor pressure
non oriented with regard to stimulus
Tropic Responses
plagiotropism- growth at an angle
thigmotropism- when touch is stimulus
negative stimulus- growth away from stimulus
chemotropism- organisms grow in response to a chemical stimulus
positive tropism- growth toward stimulus
Morphogenic Responses
fundamental change occurs metabolism
cause a change in the quality of plant life
Taxis
cells swim toward or away from stimulus
Communication Within the Plant
Perception and transduction
site of perceptive assumed to the site of transduction
suitable environment for plant development
two important factors
Presentation time
the length of time stimulus must be present for perspective cells to react and complete transduction
Threshold
the level of stimulus that must be present during presentation time to cause perception and transduction
Signal amplification cascades- initiated by a stimulus acting on a receptor that is transduce to the cell interior through secondary messengers.
Chemical messengers
different plant hormones
Gibberellins
Ethylene
Cytokinins
Auxins
Abscisic acid
Jasmonic acid
Activation and inhibition of shoots by Auxin
Apical dominance
Apically produced auxin induces in axillary buds resulting each shoot tip with one active apical meristem
Differentiation of vascular tissues
cell elongation
Auxin triggers cell elongation
Hormones as signals of environmental factors
Leaf abscission- detachment of the older leaves
Tropisms
Flowering
Photoperiodic induction to flower
Endogenous rhythms and flowering
cyclic change in the plant metabolism
cycle is controlled by internal factors by internal clock
Ripeness to flower
ABC model of organization
Three fundamental genes interact to control the basic aspects of flower organization
Gene A affects the outermost, lowest regions of a flower shoot apical meristem
Gene C controls the uppermost, central region
Gene B partially overlaps the other two
stereotyped non
