ARGONAUTE9-dependent silencing of transposable elements in pericentromeric regions of Arabidopsis.
Recent evidence indicates that the establishment of the haploid phase of the plant life cycle requires epigenetic mechanisms that control reproductive cell fate. We previously showed that in Arabidopsis thaliana (Arabidopsis) mutations in ARGONAUTE9 (AGO9) result in defective cell specification during megasporogenesis. AGO9 preferentially interacts with 24 nucleotide (nt) small RNAs (sRNAs) derived from transposable elements (TEs), and its sporophytic activity is required to silence TEs in the female gametophyte. Here we show that AGO9 can bind in vitro to 24 nt sRNAs corresponding to Athila retrotransposons expressed in the ovule prior to pollination. We also show that AGO9 is necessary to inactivate a significant proportion of long terminal repeat retrotransposons (LTRs) in the ovule, and that its predominant TE targets are located in the pericentromeric regions of all 5 chromosomes, suggesting a link between the AGO9-dependent sRNA pathway and heterochromatin formation. Our extended results point towards the existence of a tissue-specific mechanism of sRNA-dependent TE silencing in the ovule.
Grupo de Desarrollo Reproductivo y Apomixis, Laboratorio Nacional de Genómica para la Biodiversidad y Departamento de Ingeniería Genética de Plantas, Cinvestav Irapuato, México.
Noé
N
Durán-Figueroa
Jean-Philippe
JP
Vielle-Calzada
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060565:Argonaute Proteins; D002503:Centromere; D032461:Chromosomes, Plant; D004251:DNA Transposable Elements / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D020868:Gene Silencing; D018749:RNA, Plant; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
C548461:AGO9 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D004251:DNA Transposable Elements; D018749:RNA, Plant; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins