Vernalization (Revernalization, Devernalization) gene

Contain gene level Detail About Vernalization

1. Vernalization

2. It is observed in many plants flowering is primarily
controlled by light but in some cases flowering is
regulated by both light and temperature.
Vernalization is a Latin word which means "of the spring"
which literally means bringing to spring conditions.
There are two different types of strains mainly in cereals
1-Winter strain 2-Spring strain
→ If Winter stain are sown in End of September or
October they flower's in summers
→ If Spring strain are sown at the end of January or
February they also flower's in summer
→ If Winter strain are sown in January or February they
do not show flowering in summer.
Introduction
High
temperature
Devernalization
Precursor

3. ➢This stimulative effect of
temperature on
flowering is known as
Vernalization.
➢Lysenko coined the term
"Vernalization".
➢Experimentally it was observed that if winter strains are
given low temperature and sown at the end of January
and February they show flowering in summers.
→Vernalization is done at low temperature in which genetic
makeup of plants does not changes

4. Definitions
So Vernalization prepares plants for easily flowering it is reversible process in which
vernalization plays a role and it is done at low temperature.
Vernalization results in the acquisition of competence to flower. After vernalisation plants do
not initiate flowering suddenly but acquires the competence to do so. It is reversible and can
be lost as result of exposure to devernalizationconditions such as high temperature
"Acceleration of
affinity to
flowering by
chilling treatment
is known HOLL as
Vernalization".
"Vernalization is
described as
promotion of
flowering after
exposure to cold
0-5°C".
"The Cooling of
seed during
germination in
order to accelerate
flowering when it is
planted is called
Vernalization".

5. Every potentially dividing cell act as a site of vernalization. Usually
shoot apical Meristem, root Apex, apical bud, young leaves and
seeds are the best suited material for vernalization.
In Vernalization depending upon plant species various temperature
ranges are involved:
1-2°C
1-4°C
1-5°C
“Vernalization is both natural (Winters) & artificial process”.
Site of Vernalization

6. No cold exposureAfter 1 to 2 weeks cold exposureAfter 3 to 6 weeks
Artificially plants & seeds can be given low temperature
treatment by using ice cubes, cold rooms and refrigerator
etc.
Duration of low temperature treatment requires 4 days to
3 months

7. Vernalized plant material can
be reversed to be a non-
vernalized plant material
known as "Devernalization"
by using following methods:
Devernalization & Revernalization
1-High Temperature
2-Heating material at 35 to 40°C
3-Absence of Oxygen
Vernalization effect is reversible and
the process termed as devernalization.

8. A plant material can be
vernalized and devernalizedtill
its wall, membrane or seed coat
are not ruptured.
Devernalized plant
material can be reversed
by low temperature
exposure known as
"Revernalization".
Revernalization

9. Grafted
Vernalized Non-Vernalized Become Vernalized
When G. Melchers grafted a vernalized Henbane (Hyoscyamus niger) plant part to another non-
vernalized plant that have never experienced low temperature it flowered.
It suggested that some substance is found in vernalized plant is transported to non-vernalized
plant & is responsible for induction of flowering in the latter plant. This substance is termed as
vernalin. Attempts to isolate Vernalin and identify it have failed.

10. Many plants do not come to flower before they experience a
low temperature. These plants remain vegetative during warm
season, experience low temperature during winter, grow
further and then bear flowers and fruits.
Introduction
Non-Vernalized Vernalized
What is the need of
Vernalization ?

11. Shoot Apical meristem is the site of cold perception during vernalization
and that vernalization causes the meristem to become competent to
flower.
■Vernalin compound is responsible for vernalization stimulus & get
activated at low temperature.
Vernalineis hypothetical Plant growth compound as its not been
isolated yet
Vernalin formed in meristematic region.
▪However, Anton Lang have demonstrated that treatment with
Gibberellic acid (GA), a plant hormone, substitute for cold treatment in
some species of plants.
Site of cold perception

12. ➢This process have been identified in Arabidopsis thaliana. some flowering genes are involved in this process.
➢There are stable changes in the pattern of gene expression in the meristem after cold treatment
➢FLC gene( Flower locus C)-gene that acts as a repressor of flowering. FLC is highly expressed in non vernalized
shoot apical meristems. After vernalization, this gene is epigenetically switched off by an unknown mechanism
for the remainder of the plant's life cycle, permitting flowering in response to long days to occur.
❑FT gene (Flower locus T)-Gene in leaves, florigenic factor (flowering gene)
❑SOCI(SUPPRESSOR OF OVEREXPRESSION OF CONSTANSI) -gene in shoot apical meristem (flowering gene)
❑FD(flower locus D)-Gene in shoot apical meristem (flowering gene)
❑VRN2 gene is a flowering repressor down-regulated by vernalization. (in winter cereals)
❑VRNI and VIN3 is activated by Vernalization and help in flowering.
❑FRIGIDA(FRI) serves to prevent plants from flowering through the work of FLC.
Mechanism of floral induction in vernalized plant

13. If FLC Active No Flowering only vegetative phase
If FLC Inactive Flowering
Some Vernalization Genes
VRN1 Vernalization 1
VIN 3 Vernalization Insensitive 3

14. FT Gene (in Leaves)
FLC active FD Gene (in SAM )
SOC1 Gene (in SAM)
No Vernalization
Activate FLC
Inhibition of FD,FT, SOC1
No Flowering
Vernalization
Inactivate FLC
Activation of FD,FT, SOC1
Flowering
Activate VIN3, VRN1
Mechanism
Of floral
Induction in
Vernalized
Plant

15. •FLC active and
represses SOC1 and FT
•Flowering inhibited
•FLC repressed SOC1 and
FT active FT induced by
long days
•Flowering promoted
➢VRN1 not active VRN2 active,
represses FT presses F
➢Flowering inhibited
➢VRN1 active VRN2 repressed
FT active, induced by long
days
➢Flowering promoted
Arabidopsis Winter cereals
Without
Vernalization
With
Vernalization