Agriculture Reference
In-Depth Information
17
Insights into Plant Epigenome Dynamics
James Giovannoni*
US Department of Agriculture and Boyce Thompson Institute for Plant
Research, Cornell University, Ithaca, NY, USA
packaging, three-dimensional structure,
protein interactions and specifi c modifi -
cations of individual nucleotides and the
proteins that interact with them all provide
information and represent constituents of
the epigenome. Information harboured in
the epigenome in some instances is stable
and reliably inherited, while in others it is
more transient, relevant in a single or small
number of generations, and may refl ect
adaptation to localized and changing
conditions. Recent discoveries indicate
that the plant epigenome can play a myriad
of functions ranging from serving to
provide appropriate expression environ-
ments, silencing mobile genetic elements
and facilitating a means of short- or long-
term genetic 'memory', to providing
regulatory oversight for developmental
processes. Understanding these functions
and the means through which they are
attained will broaden our collective
understanding of the form and function of
the epigenome. To the extent that the
epigenome is proved to possess conserved
or fl exible variation, it may yield
additional targets for selection for crop
improvement. Plants have proved to be
important in discovery of the nature
and effects of the epigenome heralding
important initial fi ndings in Arabidopsis ,
in addition to others related to important
17.1 Introduction
Genetic information is housed and passed
to subsequent generations via the DNA
code. The epigenome provides additional
information, context and regulatory con-
straint in addition to both transient and
long-term genetic memory. The epigenome
consists of information carried in the
nature of chromatin packaging and organ-
ization, histone modifi cations (e.g. acetyl-
ation, methylation) and DNA (specifi cally
cytosine) methylation. Specifi c genes
involved in DNA or protein methylation,
acetylation, small RNA (sRNA) processing
and sRNA transcription contribute to
epigenome architecture, and their muta-
tions have provided opportunities to
develop insights into the intricacies of the
epigenome. Advanced sequencing and
informatics capabilities permit genome-
scale analyses at modest cost, resulting in
a wealth of data on epigenomes, and
their variation and dynamics in response
to development and external stimuli.
Together these tools and genetic resources
have begun to shed light on what may well
prove to be a repository of genetic infor-
mation and context as important as the
DNA code itself.
The DNA code provides information in
forms beyond DNA sequence alone. The
 
 
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