Slide 1 : Dr. Aman Biswas How plants grow and move
Circadian Clocks : Circadian Clocks Endogenous timekeepers
Keep plant responses synchronized with the environment.
Characteristics
Must continue to run in absence of external inputs
Must be about 24 hours in duration
Can be reset or entrained (to determine or modify the phase or period of )
Can compensate for temperature differences
Slide 4 : Exhibited by living cells Exhibited by dead plant parts
Xerochasy
Hygrochasy
AUTONOMIC Movements (Spontaneous) : AUTONOMIC Movements (Spontaneous)
Movements of locomotion PARATONIC or TACTIC : Movements of locomotion PARATONIC or TACTIC
Movements of Curvature(Bending in some plant parts) : Movements of Curvature(Bending in some plant parts) AUTONOMIC
Variation Movement
(Temporary bending)
Growth Movement
(Permanent bending)
Variation Movement (Temporary bending) : Variation Movement (Temporary bending) Eg. Telegraph Plant (Desmodium gyrans)
Telegraph Plant, perennial tick clover, member of the legume family, native to tropical Asia.
Telegraph Plant : Telegraph Plant The plant grows to a height of 1.2 m (4 ft) and produces pealike violet flowers.
The telegraph plant is also called the semaphone plant. It is sometimes grown as a curiosity because of the movements of the small lateral leaflets of its trifoliate leaves.
In daylight, when the air is moist and warmer than 22°C (72°F), every few minutes the leaflets jerk up and down (360o angle) like the arms of a semaphone (device for signaling using one or more movable arms). At night they droop down.
Slide 11 : Desmodium gyrans
Autonomic Growth Movements : Autonomic Growth Movements 1. HYPONASTIC
Growth is more on the lower side of petals or sepals The pictures projected on this free session belong to the beholder on the internet. We thank them
2. EPINASTIC : 2. EPINASTIC Growth more on upper side of petals or sepals
3.NUTATION : 3.NUTATION Growth rapid on one side of stem and then passes on the opposite side so that becomes ZIGZAG
Eg. Trailers and Creepers
4.CIRCUMNUTATION : 4.CIRCUMNUTATION Growth in Spiral form making structure coiled
TENDRIL and TWINERS
Paratonic Growth Movements : Paratonic Growth Movements Two kinds
PLANTS RESPOND TO ENVIRONMENTAL STIMULI : PLANTS RESPOND TO ENVIRONMENTAL STIMULI Tropisms
Plant growth toward or away from a stimulus such as light or gravity.
Nastic Movements
Response to environmental stimuli that are independent of the direction of the stimulus.
Pre-determined response.
What are Tropic Responses ? : What are Tropic Responses ? Directional movements by growth in response to a directional stimulus
Geotropic
Phototropic
Thigmotropic
or Haptotropic
Hydrotropic
Chemotropic
Thermotropic
Plant tropisms : Plant tropisms Growth in a particular direction in response to an external stimulus Response to gravity is called Gravitropism
To light is Phototropism
To touch is Thigmotropism
Geotropic = Gravitropism : Geotropic = Gravitropism Oligotropic
In response to gravity stimulus
When it grows at right angle to gravitational force
E.g.Rhizome
Plageogeotropic : Plageogeotropic When it grows at an oblique angle to gravitational force
E.g. Lateral roots and shoots
Plants Respond to Gravity : Plants Respond to Gravity Gravitropism
Response to the earth’s gravitational field.
Present at germination
Auxins play primary role
ABA secondary role
Slide 23 : Four steps
Gravity perceived by cell
Signal formed that perceives gravity
Signal transduced intra- and intercellularly
Differential cell elongation
Slide 24 : Gravitropism = Geotropism The pictures projected on this free session belong to the beholder on the internet. We thank them
Positive plageotropism : Positive plageotropism