This document discusses how epigenetic modifications allow plants to modify gene expression and flowering in response to environmental cues. It outlines several epigenetic mechanisms including DNA methylation, histone modifications, and miRNA-mediated gene regulation. These epigenetic changes affect processes like floral development and flowering time. The document explores how different epigenetic factors like DNA methylases, histone modifiers, and miRNAs regulate flowering by controlling expression of genes like FLC under various environmental conditions like cold temperatures.

1. Jatindra Mohanty, PhD

2.  Plants interact with their environment by
modifying gene expression patterns.
 One mechanism for this interaction involves
epigenetic modifications that affect a number
of aspects of plant growth and development
including floral development.
 Thus, the epigenome is highly dynamic in
response to environmental cues and floral
induction.

3.  Epigenetic is the way to control the
expression of gene.
 Epigenetic refers to heritable, self
perpetuating changes in gene activities that
are not caused by changes in nucleotide
sequence.
 It is associated with chemical modifications of
chromatin

4. 1. DNA methylation
2. Histone modification
3. miRNA mediated epigenetic modification.

5.  DNA methylation is often associated with
gene repression.
 DNA methylation occurs by covalently adding
a methyl group to cytosine of the DNA.
 In particular, flowering time in Arabidopsis
can be controlled by silencing of the homeo
domain floral transcription factor

6. Loss of function of MBD(AT MBD9)
Histone acetylation decreases & DNA methylation
increases at FLC
FLC transcript decline & early floral development
 In this process floral development occur in
vernalization (AT MBD8,9).
 Mutation of this(AT mbd8) no symptom under
cold condition

7.  Reverse genetic studies shows that
 DDM1,DDM2,MET1,DNA demethylase
gene,ROS1 under different environmental
cues affect the global level of cytosine
methylation,
 All the genes affect on the methylation which
control the flowering time
 Mutation of these genes causes the alternate
effect.

8.  Histone modifications occur when specific
lysine or arginine residues within the amino
acid terminal tail of Histone are post-
translationally modified either by Acetylation,
glycosylation, methylation,phosphorylation,
ubiquitination, SUMOylation.
 This type of modification alter the genetic
expression.

9.  Floral initiator SHK1KINASE BINDING PROTEIN1
(SKB1)
 Bind to Chromatin of FLC locus
 Increase the H4R3 symetric dimethylation(H4R3
sme2)
 Down regulated FLC expression
(early flowering)
 Late flowering occur in high salinity.

10.  Under high light Intensity HDA6 enzyme
remodel the chromatin structure.
 AtGCN5 major Histone acetyl
transferase,tightly controlling the histone
acetylation levels of their loci.
 At gcn 5 causes impaired floral production
where petals are transformed into stamens
and sepals into filamentous like-structures .
 It also other role floral development,
ex- miRNAmediated control.

11.  Cold treatment regulates epigenetic
modifiers globally like-
 NRPD1(DNA binding bromodomain
protein)
 AT GCN 5,
 HDA,
 DNA methylase etc.

12.  Trimethylation of Lys27 of H3 Histone
(H3K27me3)
Regulates the FLC region
Decrease expression of AGL19, FT, and
AGAMOUS
Effect in floral expression

13. Under high cold condition
 Induces VIN 3 (Chromatin remodeler)
Increases acetylation level
Repress FLC
 Effect on flower development

14. Under high cold condition
H3K4me3 at FLC
Repress FLC suppress ATX1
Effect on flower Floral architecture defect

15.  miRNA are control gene expression at a post
transcriptional level by global gene
expression study in AT.
 These small RNA molecules are also able to
direct DNA methylation to a particular locus
by an RNA-directed DNA methylation (RdDM)
process.
 miR160, which controls floral morphology by
modulating the expression of an AUXIN
RESPONSE FACTOR 10 (ARF10)

16. H3K27me3 at FLC mediated by miRNA(COLD
AIR)

 Triggers PRC2

 Target FLC
 Flowering effect

17.  Plants interact with their environment and
accordingly modify their flowering
programmes.
 Recent research shows that plants use
common and parallel epigenetic modification
in flowering processes under different
environmental cues.
 Together these changes underlie intricate
mechanisms that ensure plant survival and
optimize reproductive success.

18. Thank you