We can identify developmental genes
by the following comparisons
Rigidity of the body shape
The multicellularity of the animals and plants mechanisms is
That mechanism in the comparison of the genes between the
animals and plants makes up the body plan of plants and
While the homeobox and MADS box genes existed in last
common ancestor, the MADS box gene plays the role of
regulation of plant development while the homeobox genes
are important in animals.
This is a conserved sequence motif found in genes which
comprise the MADS-box gene family.
This box encodes the domain of DNA-binding MADS. This
domain allows to bind DNA sequences of high similarity to
the CC[A/T]6GG motif known as CArG-box.
The domain of DNA-binding MADS are called transcription
According to various researchers, the lengths of this box
were in the range between 168 to 180 base pairs and that is
the encoded MADS domain which has the length of 56 to 60
The MADS domain is evolved, according to some evidences,
that there is a sequence stretch of a type II topoisomerase (or
cutting of both strands of the DNA helix simultaneously in
order to manage DNA tangles and supercoils) in a common
ancestor of all extant eukaryotes.
The name of the MADS-Box Genes
M – MCM1 from the budding yeast
A – Agamous from the thale cress
D – Deficiens from the snapdragon
S – SRF from the human
Agamous – is a gene and transcription factor for the thale
SRF – also known as Serum response factor
Serum response factor
It is a transcription factor that can be found in humans.
It is considered very important especially in the development
of the embryo as it has been linked to the formation of
In animals, they are involved in muscle development, cell
proliferation and differentiation. This ranges from the
pheromone response to arginine metabolism.
2. In plants, they are involved in controlling all major aspects
of development especially in the development of
gametophytes, embryo, seed, root, flower and fruits in
both male and female.
They have homeotic functions like the homeobox (or
HOX) genes of animals. While Agamous and Deficiens for
the plants participates in the determination of floral organ
identity according to the ABC model of flower
4. The flowering time determination is also a factor in the
MADS-box gene. It has been shown to have an important
role in the integration of molecular flowering time
The genes of the 4th function are essential for the timing of
the flower bloom correctly and fertilization helps to ensure it
at the time of the maximum reproductive potential.
Homeobox or Hox Genes
They are a group of related genes that controls the body plan
of the embryo along the anterior-posterior (or head-tail)
1. Protein product is a transcription factor.
2. DNA sequence called homeobox is present
3. This are present in animals because of the same order of the
expression along the head-tail axis of the developing animal.
Animal cells are motile.
The tissues may be folded and moved against each other
On the gastrulation of metazoan, triple layered system is
built (first layer – entoderm, second layer – mesoderm,
third layer – ectoderm)
They may even move to other sites autonomously.
Plant cells are positionally fixed.
They are trapped in cells which are filled with rigid walls that
are made of cellulose which prevents the movement of cells
The plants form three basic tissue systems without
gastrulation (1st layer – dermal, 2nd layer – ground and 3rd
layer – vascular).
Rigidity of the body shape
Body plan is clearly
Highly regulated by the
determined in most parts
Animal body plan is clearly determined
in most parts.
In different life stages, they are mostly clearly determined by
If for example, they change their movement to another place
or change their short and long term behaviour, the body plan
Plant development is highly regulated
by the environment.
They are in variation and characterized by multiple times
occurs also in iterative structures.
The organ proportions and frequency may vary.
They have haploid and
Animal life cycle is just one
continuously multicellular stage
Many animals undergo one or more transformation, when
their body plan changes dramatically.
Life cycle of all plants have haploid and
That life cycle is called alternation of generations.
They are leading to two different body plants during their
life cycle (sporophyte and gametophyte)
Gametes are formed
They undergo no gametic
directly through meiosis.
meiosis, but a sporic
Animal gametes are formed directly
There is nothing that could be compared to the gametophyte
Plants undergo no gametic meiosis,
but a sporic meiosis.
The plants produces spores instead of gametes.
Gametophyte is first formed by mitotic divisions, then forms
They set aside
No reproductive stem cells
reproductive stem cells in
are set aside in the early
development of plants.
Animal species set aside reproductory stem
cells in early development.
This decreases the accumulation of mutation.
No reproductory stem cells are set
aside early in development in plants.
Some plants live still certain meristems or meristem parts
more inactive till the gametophyte is to be formed.
Distinct, complete body
Longer period of
Animals develop to a distinct, complete
Some reorganization may take place during the animal life
In seldom cases, new structures will develop.
Other animals develop stepwise into different shapes.
Plants go through a longer period of
Plants during their development do not head for a distinct
Many plants grow and develop on and on till they die.
Meristems which are areas of actively dividing
undifferentiated cells allows for iterative growth and the
formation of more and more new organs and structures
during a plants life.
Resemblance of embryonic stem cells in animals is present
yet continually existing during adult life stages.
They are determinated
Enormous plasticity in
early in development.
their development is
Animal cells are determined early in
Animal cells developed into tissues but they are clearly
determined, but in most cases, they are irreversibly
Most tissues regenerates from stem cells, however, occurs at
some animal species like Ambystoma mexicanum.
Plants show an enormous plasticity in
Axillary meristems often grows out in order to substitute for
the lost part.
Strategies resembles the regeneration of the limb in some
Whole plants can be regenerated from single cells.
Form of a plant is strongly affected by environmental factors
such as light and temperature, results in great variety of
morphologies from the same genotype.
Plant forms affected by environmental
conditions could be of:
3. Relative Portions of Vegetative and Reproductive
That amazing level of plasticity helps plants compensate for
their lack of mobility.