Plants in Motion
http://plantsinmotion.bio.indiana.edu/plantmotion
/starthere.html
Germination




Germination is the process where growth emerges from a
resting state.
If germination occurs in darkness, root growth slows after the
shoot emerges and shoot elongation accelerates.
This behavior increases the chance that the seedling will
emerge from soil into the light where it will be able to obtain
energy from sunlight by photosynthesis.
Once a seedling emerges into the light, the plant undergoes
dramatic changes such as turning green and producing leaves.
This light-dependent developmental transformation is called
photomorphogenesis.
Corn Seed Germinating
•
•
•
•
•
•
This short movie shows corn seeds germinating and growing in
darkness over a period of a few days starting 36 hours after being
planted in wet soil. The time between images in this movie was 1
hour.
Note that the root is the first part of the seedling to emerge from the
seed.
The seed on the left was planted with the embryo aligned with its root
pointing down.
The seed on the right was oriented with the embryo upside down.
As the movie shows, the roots from both seeds grew down regardless
of the initial orientation of the embryo. Also, the shoots that emerged
later grew up from both seeds.
The ability of the seedling to orient its growth occurs as a result of the
process of gravitropism. Gravitropism is the process by which plants
sense and respond to the direction of gravity.
http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/germination/germ.html
Sunflower Germination
•
•
•
This movie shows germination and early growth of sunflower
seedlings under low intensity white light. The time between images in
this movie was 1 hour and they are shown at 6 frames per sec
As the seedlings emerge from the soil, they are already beginning to
make chlorophyll and turn green. The cotyledons and apical hook
unfold as the plant emerges into the light.
One of the more striking things is the robust nutational movement
(rotation of the stem) shown by these seedlings under continuous dim
light. In darkness and in bright light, the nutational movement is
present but less robust (see photomorphogenesis movie for
comparison). It is almost like the seedlings are searching for a better
light source..
http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/germination/germ.html
Arabidopsis thaliana
Germination
•
•
•
•
This short movie shows Arabidopsis thaliana seeds
germinating in the light.
Once the root has emerged and anchored the plant, the
shoot begins to grow. As the shoot is exposed to the light,
the plant undergoes the process called
photomorphogenesis.
As the seedlings emerge from the soil, they are already
beginning to make chlorophyll and turn green.
The cotyledons and apical hook unfold as the plant
emerges into the light. and the cotyledons expand and turn
green and the seedling begins to grow photosynthetically
and no longer depends on food stored in the seed
http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/germination/germ.html
Photomorphogenesis
Plant development is dependent on the
environmental conditions where it is growing. The
process by which plant development is controlled by
light is called photomorphogenesis. Typically,
photomorphogenic responses are most obvious in
germinating seedlings but light affects plant
development in many ways throughout all stages of
development. The movies in this section will
demonstrate some of the photomorphogenic
responses in plants.
http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/photomorph/photomorph.html
Sunflower germination dark
•
•
•
•
The movie on the left documents the growth of sunflower seedlings in
darkness. Because the seedlings were imaged with infrared
illumination, the movie is in black and white. However, the seedlings
did not turn green like the light-grown seedlings in the other movie.
While in the darkness of the soil, seedlings are dependent on stored
food reserves in the embryo.
Plants put most of their energy into stem elongation and suppress leaf
development and chlorophyll production (i.e. they do not turn green).
In addition, dark-grown dicotyledonous plants keep the end of the
stem hooked and their cotyledons closed together. Presumably, this
growth strategy is an adaptation for rapidly emerging from the dark
soil.
http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/photomorph/photomorph.html
Sunflower germination light
•
•
•
•
The movie on the right documents the growth of
sunflower seedlings under white light.
The movie shows shows approximately 2 days of growth.
By advancing the movie frame by frame, the effects of
light on plant development can readily be seen.
When a seedling emerges from the soil into the light,
growth and development changes dramatically.
Elongation is suppressed, the apical hook opens and the
cotyledons separate, enlarge and turn green as
chloroplast's develop for carrying out photosynthesis.
http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/photomorph/photomorph.html
Tropism
Tropisms are directional movement
responses that occur in response to a
directional stimulus. One of the most
commonly observed tropic responses in
plants is phototropism, in which plant stems
grow towards light.
http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/tropisms.html
Cool Corn



After 3 days of growth in darkness, the pot of corn
seedlings in this movie were exposed to light from a
single light bulb placed in the center of the pot just above
the seedling. The plants were then imaged at 10 min
intervals for about 18 hours.
For the first 14 hours the seedlings appear to be
worshiping the light as they maintain phototropic
curvature.
After 14 hours, the point light source was turned off and
diffuse room lighting was turned on and the seedlings
quickly return to a vertical orientation.
http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html
Vegetative Phase




The period of growth between germination and
flowering is known as the vegetative phase of plant
development.
During the vegetative phase, plants are busy
carrying out photosynthesis and accumulating
resources that will be needed for flowering and
reproduction.
Different types of plants show different growth
habits.
The movies in this section will document various
growth processes that occur during the vegetative
phase of development.
http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html
Rosette Plant
•
•
•
•
The time-lapse movie shows the development of a rosette
over a period of approximately 13 days, starting from
about a week after germination.
The seedlings were grown in continuous light for the
movie but had been in a 12 h photoperiod prior to filming.
If you look closely at the cotyledons and leaves as they
grow, you can see that the leaves exhibit brief periods of
movement (they appear to wiggle) approximately every
24 hours.
These movements are most likely due to the action of the
circadian clock that had been entrained prior to moving
the plants to continuous light. The time interval between
images in the movie is 4 hours.
http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html
Time Course of leaf area increase
•
•
•
•
The graph above shows the timecourse of the increase in leaf area of
the plants shown in the time-lapse
movie.
The data shown were obtained from
images captured every hour (the
movie only shows images 4 hours
apart).
In addition, data from several
seedlings were averaged with the data
obtained from the seedling in the
time-lapse movie.
After about 12 days, it appears that
growth starts to decrease. However,
this apparent decrease is the result of
leaves overlapping each other as the
leaves expanded so that they were no
longer detected by the automated
technique used to measure the leaf
area.
http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html
Root Growth




The main root of a plant typically grows downwards
towards earths gravity.
This downwards oriented growth is termed positive
gravitropism.
As a root elongates, the cells behind the root apical
meristem differentiate, with some epidermal cells forming
root hairs.
Root hairs are thought to function in uptake of water and
minerals from the soil.
http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html
Wilting
•
•
•
•
•
Water makes up about 95% of the fresh weight of a plant.
Water is essential for plants to take up nutrients from the
soil and deliver them through the plant body.
When water becomes limiting, plants are said to "wilt".
Wilting occurs when water availability is seriously
limiting and can lead to damage or death if wilting goes
on too long.
Fortunately, if additional water is provided before serious
damage occurs, a plant will quickly rehydrate and resume
normal growth and metabolism.
The time-lapse movie here shows a coleus plant wilting as
the soil in the pot become progressively drier.
http://plantsinmotion.bio.indiana.edu/plantmotion/vegetative/veg.html