DNA Research Advance Access published online on December 1, 2007
DNA Research, doi:10.1093/dnares/dsm022
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Specific Enrichment of miRNAs in Arabidopsis thaliana Infected with Tobacco mosaic virus
1 Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan
2 Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
3 RIKEN Plant Science Center, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
Received 28 May 2007 ; accepted 6 November 2007.
RNA silencing is a broadly conserved machinery and is involved in many biological events. Small RNAs are key molecules in RNA silencing pathway that guide sequence-specific gene regulations and chromatin modifications. The silencing machinery works as an anti-viral defense in virus-infected plants. It is generally accepted that virus-specific small interfering (si) RNAs bind to the viral genome and trigger its cleavage. Previously, we have cloned and obtained sequences of small RNAs from Arabidopsis thaliana infected or uninfected with crucifer Tobacco mosaic virus. MicroRNAs (miRNAs) accumulated to a higher percentage of total small RNAs in the virus-infected plants. This was partly because the viral replication protein binds to the miRNA/miRNA* duplexes. In the present study, we mapped the sequences of small RNAs other than virus-derived siRNAs to the Arabidopsis genome and assigned each small RNA. It was demonstrated that only miRNAs increased as a result of viral infection. Furthermore, some newly identified miRNAs and miRNA candidates were found from the virus-infected plants despite a limited number of examined sequences. We propose that it is advantageous to use virus-infected plants as a source for cloning and identifying new miRNAs.
Key words: Arabidopsis thaliana; Tobacco mosaic virus; microRNA; RNA silencing
* To whom correspondence should be addressed. Tel. +81-3-5454-6776. Fax. +81-3-5454-6776. E-mail: solan{at}bio.c.u-tokyo.ac.jp