Epigenetic modifications are highlighted
for their great importance in regulating plant development, but their function
associated with single-cell differentiation remains undetermined. Here, we used
the cotton fibre, which is the epidermal hair on the cotton ovule, as a model
to investigate the regulatory role of DNA methylation in cell differentiation.
The level of CHH (H = A, T, or C) DNA methylation level was found to increase
during fibre development, accompanied by a decrease in RNA-directed DNA methylation
(RdDM). Examination of nucleosome positioning revealed a gradual transition
from euchromatin to heterochromatin for chromatin dynamics in developing
fibres, which could shape the DNA methylation landscape. The observed increase
in DNA methylation in fibres, compared with other ovule tissue, was
demonstrated to be mediated predominantly by an active H3K9me2-dependent
pathway rather than the RdDM pathway, which was inactive. Furthermore,
integrated multi-omics analyses revealed that dynamic DNA methylation played a
role in the regulation of lipid biosynthesis and spatio-temporal modulation of
reactive oxygen species during fibre differentiation. Our study illustrates two
divergent pathways mediating a continuous increase of DNA methylation and also
sheds further light on the epigenetic basis for single-cell differentiation in
plants. These data and analyses are made available to the wider research
community through a comprehensive web portal.
http://nar.oxfordjournals.org/content/early/2016/04/11/nar.gkw238.abstract
doi: 10.1093/nar/gkw238(IF=9.112)