title: Phytohormone abscisic acid control RNA-dependent RNA polymerase 6 gene expression and post-transcriptional gene silencing in rice cells.
abstract: RNA-dependent RNA polymerase 6 (RDR6) catalyses dsRNA synthesis for post-transcriptional gene silencing (PTGS)-associated amplification and the generation of endogeneous siRNAs involved in developmental determinations or stress responses. The functional importance of RDR6 in PTGS led us to examine its connection to the cellular regulatory network by analyzing the hormonal responses of RDR6 gene expression in a cultured cell system. Delivery of dsRNA, prepared in vitro, into cultured rice (Oryza sativa cv. Japonica Dongjin) cells successfully silenced the target isocitrate lyase (ICL) transcripts. Silencing was transient in the absence of abscisic acid (ABA), while it became persistent in the presence of ABA in growth medium. A transcription assay of the OsRDR6 promoter showed that it was positively regulated by ABA. OsRDR6-dependent siRNA(ICL) generation was also significantly up-regulated by ABA. The results showed that, among the five rice OsRDR isogenes, only OsRDR6 was responsible for the observed ABA-mediated amplification and silencing of ICL transcripts. We propose that ABA modulates PTGS through the transcriptional control of the OsRDR6 gene.
authors.affiliation: The Basic Science Research Institute, Department of Biological Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Yang
authors.forename: Hyun Hee
authors.initials: HH
authors.lastname: Seo
authors.forename: So Jung
authors.initials: SJ
authors.lastname: Han
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Yoon
authors.forename: Moon Sik
authors.initials: MS
authors.lastname: Yang
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Lee
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant; D007522:Isocitrate Lyase / Q000096:biosynthesis / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics*; D034622:RNA Interference; D012324:RNA-Dependent RNA Polymerase / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D010937:Plant Growth Regulators; D010940:Plant Proteins; D000040:Abscisic Acid; D012324:RNA-Dependent RNA Polymerase; D007522:Isocitrate Lyase