During sexual reproduction, development of a totipotent zygote from the fusion of highly differentiated gametes is accompanied by a dynamic regulation of gene expression. This notably involves RNA silencing operated by Argonautes (AGO) effector proteins. While AGOs roles during Arabidopsis somatic life have been extensively investigated, less is known about their expression during reproduction, which proceeds via double-fertilization of an egg and a central cell, leading respectively to the embryo and a supportive tissue known as endosperm. Using full-locus translational reporters for all ten Arabidopsis AGOs, we uncover cell-specific expression patterns and AGO-intrinsic subcellular localizations in reproductive tissues. However, while some Arabidopsis AGOs are enriched in both male and female gametes, i.e. sperm and egg cells, they are comparably low-expressed in accessory, i.e. vegetative and central cells. Likewise, following fertilization, several AGOs are expressed in the early embryo, yet below detection in the early endosperm. Thus, there is pre- and post-fertilization asymmetry between the embryo and endosperm lineages. Later during embryo development, AGO9, AGO5 and AGO7 are restricted to the apical embryonic meristem in contrast to AGO1, AGO4, AGO6 and AGO10. Beside shedding some light onto Arabidopsis reproduction, the plant material generated here should constitute a valuable asset to the RNA silencing community by enabling functional AGOs studies.


DNA methylation is an important epigenetic mark required for proper gene expression and silencing of transposable elements. DNA methylation patterns can be modified by environmental factors such as pathogen infection, where modification of DNA methylation can be associated with plant resistance. To counter the plant defense pathways, pathogens produce effectors molecule, several of which act as proteasome inhibitors. Here we investigated the effect of proteasome inhibition by the bacterial virulence factor Syringolin A on genome-wide DNA methylation. We show that Syringolin A treatment results in an increase of DNA methylation at centromeric and pericentromeric regions of Arabidopsis chromosomes. We identify several CHH DMRs that are enriched in the proximity of transcriptional start sites. Syringolin A treatment does not result in significant changes in small RNA composition. However, significant changes in genome transcriptional activity can be observed, including a strong upregulation of resistance genes that are located on chromosomal arms. We hypothesize that DNA methylation changes could be linked to the upregulation of some atypical members of the de novo DNA methylation pathway: AGO3, AGO9 and DRM1. Our data suggests that modification of genome-wide DNA methylation resulting from an inhibition of the proteasome by bacterial effectors could be part of a epi-genomic arms race against pathogens.




Grob S, Bonnet DMV, Tirot L and Jullien PE*. Methylome dynamics upon proteasome inhibition by the pseudomonas virulence factor Syringolin A. BioXriv.



Devers, Emanuel A.; Brosnan, Christopher A.; Sarazin, Alexis; Albertini, Daniele; Amsler, Andrea C.; Brioudes, Florian; Jullien, Pauline E.; Lim, Peiqi; Schott, Gregory; Voinnet, Olivier (2020). Movement and differential consumption of short interfering RNA duplexes underlie mobile RNA interference. Nature plants, 6(7), pp. 789-799. Springer Nature 10.1038/s41477-020-0687-2

Jullien, P.E., Grob, S., Marchais, A., Pumplin, N., Chevalier, C., Bonnet, D.M., Otto, C., Schott, G. and Voinnet, O. (2020), Functional characterization of Arabidopsis ARGONAUTE 3 in reproductive tissues. Plant J. Accepted Author Manuscript. doi:10.1111/tpj.14868

Jullien,  pauline E., Bonnet, D.M. V, Pumplin, N., Schroeder, J.A. and Voinnet, O. (2020) ASYMMETRIC EXPRESSION OF ARGONAUTES IN ARABIDOPSIS REPRODUCTIVE TISSUES. bioRxiv, 2020.05.18.102863. Available at:



Schröder, Jens A.; Jullien, Pauline E. (2019). The Diversity of Plant Small RNAs Silencing Mechanisms. CHIMIA, 73(5), pp. 362-367. 10.2533/chimia.2019.362


2018 and older

Jullien, Pauline E.; Grob, Stefan; Marchais, Antonin; Pumplin, Nathan; Chevalier, Clement; Otto, Caroline; Schott, Gregory; Voinnet, Olivier (18 December 2018). Functional characterization of Arabidopsis ARGONAUTE 3 in reproductive tissue (bioRxiv 500769). Cold Spring Harbor Laboratory 10.1101/500769

Tschopp, MA; Iki; T, Brosnan, CA; Jullien, PE; Pumplin, N. (2017). A complex of Arabidopsis DRB proteins can impair dsRNA processing. RNA, 23, pp. 782-797. 10.1261/rna.059519.116

Pumplin, N; Sarazin, A; Jullien, PE; Bologna, NG; Oberlin, S; Voinnet, O. (2016). DNA Methylation Influences the Expression of DICER-LIKE4 Isoforms, Which Encode Proteins of Alternative Localization and Function. The Plant Cell, 28(11), pp. 2786-2804. 10.1105/tpc.16.00554

Calarco, JP; Borges, F; Donoghue, MT; van Ex, F; Jullien, PE; Lopes, T; Gardner, R; Berger, F; Feijó, JA; Becker, JD; Martienssen, RA. (2012). Reprogramming of DNA methylation in pollen guides epigenetic inheritance via small RNA. Cell, 151(1), pp. 194-205. 10.1016/j.cell.2012.09.001

Jullien, PE; Susaki, D; Yelagandula, R; Higashiyama, T; Berger, F. (2012). DNA methylation dynamics during sexual reproduction in Arabidopsis thaliana. Current Biology, 22(19), pp. 1825-1830. 10.1016/j.cub.2012.07.061

Jullien, PE; Berger, F. (2010). DNA methylation reprogramming during plant sexual reproduction? Trends in Genetics, 26(9), pp. 394-399. 10.1016/j.tig.2010.06.001

Jullien, PE; Berger, F. (2010). Parental Genome Dosage Imbalance Deregulates Imprinting in Arabidopsis. PLoS Genetics, 6(3), e1000885. 10.1371/journal.pgen.1000885

Jullien, PE; Berger, F. (2009). Gamete-specific epigenetic mechanisms shape genomic imprinting. Current Opinion in Plant Biology 12(5), pp. 637-642. 10.1016/j.pbi.2009.07.004

Jullien, PE; Berger, F. (2008). Parental genomic imprinting in plants: significance for reproduction. Medecine sciences, 24(8-9), pp. 753-757. 10.1051/medsci/20082489753

Jullien, PE; Mosquna, A; Ingouff, M; Sakata, T; Ohad, N; Berger, F. (2008). Retinoblastoma and its binding partner MSI1 control imprinting in Arabidopsis. PLoS Biology, 6(8), e194. 10.1371/journal.pbio.0060194

Aubourg, S; Martin-Magniette, ML; Brunaud, V; Taconnat, L; Bitton, F; Balzergue, S; Jullien, PE; Ingouff, M; Thareau, V; Schiex, T; Lecharny, A; Renou, JP. (2007). Analysis of CATMA transcriptome data identifies hundreds of novel functional genes and improves gene models in the Arabidopsis genome. BMC Genomics, 8, 401. 10.1186/1471-2164-8-401

Ingouff, M; Jullien, PE; Berger, F. (2006). The female gametophyte and the endosperm control cell proliferation and differentiation of the seed coat in Arabidopsis. The Plant Cell, 18(12), pp. 3491-3501. 10.1105/tpc.106.047266

Jullien, PE; Kinoshita, T; Ohad, N; Berger, F. (2006). Maintenance of DNA methylation during the Arabidopsis life cycle is essential for parental imprinting. The Plant Cell, 18(6), pp. 1360-1372. 10.1105/tpc.106.041178

Jullien, PE; Katz, A; Oliva, M; Ohad, N; Berger, F.  (2006) Polycomb group complexes self-regulate imprinting of the Polycomb group gene MEDEA in Arabidopsis. Current Biology, 16(5), pp. 486-492. 10.1016/j.cub.2006.01.020

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