Plant Behaviour Flashcards
(17 cards)
Plant Behavioral Response
Movement:
- bending, twisting, rotating
- rapid movement as in sensitive plant
Growth:
- seed germination
- seasonal production of reproductive structures
- defensive response to attack
Tropisms defeniton
when a plant moves in response to an external stimulus in the environment
- growth toward or away from stimulus
Heliotropism - “Sun Tracking”
- Diurnal motion of plant in response to direction of sun
- motor cells : pump K+, turgor P
- Maintains ideal temp/humidity
- favors pollen development
Phototropism (Light)
- Occurs bc cells on shady side of stem elongate
- A pigment related to riboflavin acts as photoreceptors when phototropism occurs
- Auxin migrates to shady side of stem
- Shady sides elongate faster than bright side
Photoperiodism
plants ability to measure/respond to light around or day length
short day plants: flower when day length us shorter then critical length
Long day plants: flower when day length is longer then critical length
Day neutral plants: do not depend on day length for flowering
Gravitropism (Gravity)
- When plant is placed on its side, stem grows upwards, opposite pull of gravity
- Stems with root caps grown downward (contain statoliths - starch granules)
- Auxin is responsible for:
positive gravitropism of roots
Negative gravitropism of shoots
Thigmotropism (Touch)
- unusual growth due to contact with solid object (ex. coiling tendrils)
- Occurs when entire plant responds to presence if environmental stimuli (rain, wind)
Nastic (Nutational) Movements
- do not involve plant growth
- dependent on stimulus direction
Seismonastic movements: - touch
- shaking
- thermal stimulus
Sleep movements: - occur daily in response to light/dark changes
- prayer plant
Plant Hormones
Almost all communication in a plant is done by hormones
- Synthesized in one part of the plant
- Travels within phloem in response to the appropriate stimulus
- 5 commonly recognized groups
exert effects when bind to protein receptor’s
Auxins - “Master” Plant Hormones
- Influences structure, development, behavior
- produced shoot apical meristem and is found in young leaves and in flowers and fruits
- Apically produced auxin prevents the growth of axillary bids
Apical dominance: - weak solution applied to woody cutting causes rapid growth of adventitious roots
- mediates phototropism (light)
Cytokinins
- A class of hormones that promote cell division
- derivatives of adenine (made primarily in root tips)
- prevent senescence (the process of cells permanently stopping division)
- initiate growth; cell specialization
Gibberellins - Gibberellic Acid
- Growth promoting hormones; cell elongation
- produced in apical buds, roots, young leaves, seed embryos
- Involved in stem elongation, breaking of dormancy, seed germination, flowering, retards leaf and fruit aging
Ethylene
Involved in abscission: the natural shedding or dropping of plant organs like leaves, flowers, or fruits
Ethylene stimulates certain enzymes
- leaf and flower aging, fruit ripening
- Promotes leaf and fruit dropping
- stress response
- seedling germination
Abscisic Acid (ABA) defenition
a plant hormone that plays a crucial role in plant growth, development, and stress responses, particularly in response to water stress.
Abscisic Acid (ABA)
- Initiates & maintains seed and bud dormancy
- stimulates bud scale formation
- brings about closure of stomata
- slows, stops metabolism in stress response
Produced by: - any green tissue w/ chloroplasts
- monocot endosperm
- roots
Brassinosteroids definition
a group of polyhydroxylated steroidal phytohormones that are required for the development, growth, and productivity of plants
- Chemically related to animal steroid hormones
- receptors are plasma membrane kinases (not in nucleus)
- 40 different compounds identified
Brassinosteroids
- promotes cell elongation
- shoot elongation
- stimulates xylem development
- retards leaf drop
- promotes stress response
- can be applied to protect plants from heat, cold, high, salinity, injury, diseases
