Small Silencing RNAs in Plants Are Mobile and Direct Epigenetic Modification in Recipient Cells

• Published in: Science (American Association for the Advancement of Science) 2010-05, Vol.328 (5980), p.872-875
• Main Authors: Molnar, Attila, Melnyk, Charles W, Bassett, Andrew, Hardcastle, Thomas J, Dunn, Ruth, Baulcombe, David C
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological and medical sciences; DNA; DNA Methylation; DNA Transposable Elements; DNA, Plant - genetics; DNA, Plant - metabolism; Epigenesis, Genetic; Epigenetics; Flowers & plants; Fundamental and applied biological sciences. Psychology; Gene expression; Genes, Plant; Genetic loci; Genetics and breeding of economic plants; Genome, Plant; Genomics; Graftage; Methylation; MicroRNAs - genetics; MicroRNAs - metabolism; Plant biology; Plant roots; Plant Roots - cytology; Plant Roots - genetics; Plant Roots - metabolism; Plant Shoots - cytology; Plant Shoots - genetics; Plant Shoots - metabolism; Plants; Plants, Genetically Modified; RESEARCH ARTICLE; Ribonucleic acid; RNA; RNA Interference; RNA, Plant - genetics; RNA, Plant - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Tissue grafting
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1187959

A silencing signal in plants with an RNA specificity determinant moves through plasmodesmata and the phloem. To identify the mobile RNA, we grafted Arabidopsis thaliana shoots to roots that would be a recipient for the silencing signal. Using mutants that block small RNA (sRNA) biogenesis in either source or recipient tissue, we found that transgene-derived sRNA as well as a substantial proportion of the endogenous sRNA had moved across the graft union, and we provide evidence that 24-nucleotide mobile sRNAs direct epigenetic modifications in the genome of the recipient cells. Mobile sRNA thus represents a mechanism for transmitting the specification of epigenetic modification and could affect genome defense and responses to external stimuli that have persistent effects in plants.