Calendar Name: seminars
Scheduled for: Friday, September 2 2011, 14:00 - 15:30
Event text: Dr Martin Crespi
Institut des Sciences V�g�tales
CNRS
Universit� Paris
Gif sur Yvette/Paris
FRANCE
Details: �Impact of non-coding RNAs in root developmental
plasticity�
ABSTRACT
Long non-protein coding RNAs (npcRNA) represent an
emerging class of riboregulators, which act either
directly in this long form or are processed to shorter
miRNA and siRNAs. Plant and animals use small RNAs
(microRNAs and siRNAs) as guide for post-transcriptional
and epigenetic regulation. In plants, miRNAs and
trans-acting siRNA (tasiRNA) result from different
biogenesis pathways but both interact with target
transcripts to direct their cleavage. Genome-wide
bioinformatic analysis of full-length cDNA databases
allowed us to identify 76 Arabidopsis long npcRNAs.
Eleven npcRNAs were antisense to protein-coding mRNAs
whereas certain corresponded to miRNA or siRNA
precursors. In addition, numerous 24-nt siRNAs matched
to five different npcRNAs. To link them to root
developmental plasticity, we have shown that abiotic
stresses and hormone treatments in roots altered the
accumulation of 22 of these npcRNAs.
Functional studies are ongoing to understand the
regulatory mechanisms involving npcRNAs and their
interacting RNA binding proteins in root tissues. We
have identified an RNA-binding protein that interacts
with an npcRNA that accumulates in nuclear �speckles�
and controls auxin responses. In addition, one npcRNA
expressed in root tissues corresponded to TAS3a, a
tasiRNA precursor target of miR390. A feedback mechanism
involving miR390/tasiRNAs and their ARF targets
quantitatively controls lateral root emergence. Finally,
the npcRNA43 locus was transcribed in sense/antisense
orientation and its overexpression led to a
developmental phenotype suggesting a novel compensatory
mechanism mediated by an antisense RNA to control gene
expression. We think that environmental control of long
and small npcRNAs through interactions with RBPs may
fine tune expression patterns of regulatory genes to
modulate root developmental plasticity.
