Attila Molnar, Charles Melnyk and colleagues in the Baulcombe group have discovered a new type of signal molecule in plants. In a paper published online in Science (23/4/2010) they show that small RNA molecules, known as small interfering RNAs, can migrate long distances in plants and they can direct chemical modification of DNA in the recipient cells. This modification – DNA methylation – normally results in the silencing of gene expression that persists through cell divisions even if the mobile RNA is no longer present. The newly discovered signal could explain many mysterious phenomena in plant biology in which a local stimulus induces a long term and persistent effect in the recipient tissues.
"Small silencing RNAs in plants are mobile and they direct epigenetic modification in recipient cells"
Attila Molnar*, Charles W. Melnyk*, Andrew Bassett, Thomas J. Hardcastle, Ruth Dunn, David C. Baulcombe
The abstract and full text of the paper can be downloaded from
http://www.plantsci.cam.ac.uk/research/baulcombe/publications.html.
Image: Silencing of the GFP reporter gene in Arabidopsis roots by mobile small RNAs derived from GFP silenced shoots. Imaged using UV fluorescence, the green colour indicates non-silenced GFP fluorescing roots and red indicates silenced auto-fluorescencing tissue.
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