Chapter 39 Flashcards
Etiolation
Physical adaptations for growing in darkness
De-etiolation
After exposure to light, plant greens meaning the shoots and roots grow normally again
Different ways that plants can detect light
Intensity, spectral composition, direction it’s coming from, spatial gradient of intensity, amount of time it’s available
Photomorphogenesis
Effects of light on plant morphology
Two different classes of light receptors
Blue-light photoreceptors, phytochromes
Blue-light photoreceptors
Absorb blue light
What plant responses does blue light initiate?
Hypocotyl elongation, stomata opening, phototropism
Cryptochromes
Blue-light receptors involved in inhibition of stem elongation
Phototropin
Protein kinase involved in mediating blue-light-mediated stomatal opening, chloroplast movements, and phototropic curvatures
Phytochromes
Pigments that absorb mostly red and far-red light ; red light increases germination, far-red light inhibits germination
Responses to Pfr
Seed germination ; inhibition of vertical growth and stimulation of branching ; setting internal clocks ; control of flowering
What does red light trigger verse far-red light
Red light converts Pr to Pfr ; far-red light converts Pfr to Pr
Shade avoidance response
When a tree is shaded, the phytochrome ratio shifts in favor of Pr inducing vertical growth
Photoperiodism
The environmental stimulus plants use most often to detect the time of year
Gravity
A constant force and critical environmental cue for plants to determine the growth pattern
Gravitropism
Response to gravity ; roots show positive gravitropism (grow down) ; shoots show negative gravitropism (grow up)
How can plants detect gravity?
By the settling of statoliths, which are dense cytoplasmic components
Thigmomorphogenesis
Refers to changed in form that result from mechanical disturbance ; growth in response to touch
Action potentials
Transmission of electrical impulses
Phytotoxins
Metabolites (bioproducts) produced by plant pathogens to damage the cell plants ; affect photosynthesis, germination, and root and shoot growth
Eavesdropping
Chemical defense signals can be detected by eavesdropping neighbors and used to prime their own defenses ; targeted to other branches of the same plant or to insect bodyguards
Plant hormones
May act via signaling by removing a repress or from a transcription factor that stimulates the expression of growth-promoting genes
Ubiguitin
Protein that binds covalently to another protein and targets it for breakdown
What are some example of things Auxin does?
(Indole-3 acetic acid) root initiation ; leaf and fruit abscission ; apical dominance ; fruit development ; cell expansion