Scientists from Tokyo University of Science have discovered a new way to
regenerate plant tissues. Plant regeneration occurs through the formation of
a mass of pluripotent cells. Pluripotency involves silencing
[www.isaaa.org] genes
to remove original tissue memory and priming for activation by external
input. The scientists, led by Professor Sachihiro Matsunaga have shown that
plant regenerative capacity requires a certain demethylase that can prime
gene expression in response to regenerative cues.

Using Arabidopsis thaliana, Professor Matsunaga and his team studied
genome-wide histone modifications. Histones are proteins that package
together eukaryotic DNA, preventing it from being transcribed or decoded.
Upon modification, however, these proteins' grasp around the DNA molecule
loosens, making it easier for the DNA to be transcribed. The scientists
found that it is the demethylation (the removal of a methyl group from the
amino acid) of the histone H3 by the LDL3 enzyme that lends regenerative
competency to the plant. This epigenetic mechanism allows the plant's
pluripotent cells to go back to its unipotent state and thus assume the
identity of shoot meristems for differentiated tissues including leaves and
stems.

[www.tus.ac.jp]