title: Cell-autonomous-like silencing of GFP-partitioned transgenic Nicotiana benthamiana.
abstract: We previously reported the novel partitioning of regional GFP-silencing on leaves of 35S-GFP transgenic plants, coining the term "partitioned silencing". We set out to delineate the mechanism of partitioned silencing. Here, we report that the partitioned plants were hemizygous for the transgene, possessing two direct-repeat copies of 35S-GFP. The detection of both siRNA expression (21 and 24 nt) and DNA methylation enrichment specifically at silenced regions indicated that both post-transcriptional gene silencing (PTGS) and transcriptional gene silencing (TGS) were involved in the silencing mechanism. Using in vivo agroinfiltration of 35S-GFP/GUS and inoculation of TMV-GFP RNA, we demonstrate that PTGS, not TGS, plays a dominant role in the partitioned silencing, concluding that the underlying mechanism of partitioned silencing is analogous to RNA-directed DNA methylation (RdDM). The initial pattern of partitioned silencing was tightly maintained in a cell-autonomous manner, although partitioned-silenced regions possess a potential for systemic spread. Surprisingly, transcriptome profiling through next-generation sequencing demonstrated that expression levels of most genes involved in the silencing pathway were similar in both GFP-expressing and silenced regions although a diverse set of region-specific transcripts were detected.This suggests that partitioned silencing can be triggered and regulated by genes other than the genes involved in the silencing pathway.
authors.affiliation: National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA), Suwon 441-707, Korea sohnseonghan@korea.kr.
authors.forename: Seong-Han
authors.initials: SH
authors.lastname: Sohn
authors.affiliation: College of Natural Resources, University of California, Berkeley CA94720, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Frost
authors.affiliation: National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA), Suwon 441-707, Korea.
authors.forename: Yoon-Hee
authors.initials: YH
authors.lastname: Kim
authors.affiliation: National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA), Suwon 441-707, Korea.
authors.forename: Seung-Kook
authors.initials: SK
authors.lastname: Choi
authors.affiliation: College of Agricultural, Life and Environmental Sciences, Chungbuk National University, Cheongju 361-763, Korea.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lee
authors.affiliation: National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA), Suwon 441-707, Korea.
authors.forename: Mi-Suk
authors.initials: MS
authors.lastname: Seo
authors.affiliation: National Academy of Agricultural Science (NAAS), Rural Development Administration (RDA), Suwon 441-707, Korea.
authors.forename: Sun-Hyung
authors.initials: SH
authors.lastname: Lim
authors.affiliation: Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
authors.forename: Yeonhee
authors.initials: Y
authors.lastname: Choi
authors.affiliation: College of Agriculture and Life Sciences (CALS), Seoul National University, Seoul 151-747, Korea.
authors.forename: Kook-Hyung
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Biological Chemistry, John Innes Centre (JIC), Colney Lane, Norwich NR4 7UH, UK.
authors.forename: George
authors.initials: G
authors.lastname: Lomonossoff
mesh_terms: D020869:Gene Expression Profiling; D020868:Gene Silencing; D049452:Green Fluorescent Proteins; D010641:Phenotype; D030821:Plants, Genetically Modified; D012091:Repetitive Sequences, Nucleic Acid; D014026:Nicotiana / Q000235:genetics*; D019076:Transgenes
chemical_list: D049452:Green Fluorescent Proteins
keywords: GFP-partitioned silencing; Nicotiana benthamiana; cell-autonomous-like silencing; post-transcriptional gene silencing; systemic silencing.