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Methylome response to proteasome inhibition by the Pseudomonas syringae virulence factor Syringolin A

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 effector molecules, 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 an epi-genomic arms race against pathogens.

Read More in Molecular Plant-Microbe Interactions

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Non-cell-autonomous small RNA silencing in Arabidopsis female gametes

In recent years, small RNA movement has been both hypothesized and shown to be an integral part of the epigenetic DNA methylation reprogramming occurring during plant reproduction. It was suggested that the release of epigenetic silencing in accessory cell types or tissues is necessary to reinforce epigenetic silencing in the gametes (egg cell and sperm cells), which would in turn ensure the genomic stability of the next generation plant. In Arabidopsis thaliana, small RNA (sRNA) movement was indeed shown to occur during male gametogenesis. However, the situation within the female gametophyte and in early seed development is mostly unknown. Here, we show that small RNAs can induce non-cell-autonomous silencing from the central cell toward the egg cell but also from the synergids to the egg cell and central cell. Our data show that in addition to the movement of sRNAs during pollen development, hairpin RNAs can have non-cell-autonomous effects in the female gametes.

Read More in Current Biology



DMV Bonnet, L Tirot, S Grob, PE Jullien. Methylome response to proteasome inhibition by the Pseudomonas syringae virulence factor Syringolin A. Molecular Plant-Microbe Interactions 2023,

JA Schröder, DMV Bonnet, PE Jullien*. Non-cell autonomous small RNA silencing in Arabidopsis female gametes. Current biology 2023, 33 (1), 183-188. e3 doi:


Tirot L, Jullien PE*: Epigenetic dynamics during sexual reproduction: At the nexus of developmental control and genomic integrity. Current Opinion in Plant Biology 2022, 69:102278.

Tirot L, Bonnet DMV, Jullien PE*. DNA Methyltransferase 3 (MET3) is regulated by Polycomb group complex during Arabidopsis endosperm development. PlantReprod. 2022 Jan 28. doi: 10.1007/s00497-021-00436-x.

Oliver C, Annacondia ML, Wang Z, Jullien PE, Slotkin RK, Köhler C, Martinez G. The miRNome function transitions from regulating developmental genes totransposable elements during pollen maturation. Plant Cell. 2022 Feb3;34(2):784-801. doi: 10.1093/plcell/koab280.

Jullien PE*, Schröder JA, Bonnet DMV, Pumplin N, Voinnet O. Asymmetric expression of Argonautes in reproductive tissues. Plant Physiol. 2022 Jan 20;188(1):38-43. doi: 10.1093/plphys/kiab474.


Tirot, L.; Jullien, P.E*.; Ingouff, M*. Evolution of CG Methylation Maintenance Machinery in Plants. Epigenomes 2021, 5, 19.

Bonnet DMV, Grob S, 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. 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.  doi:10.1111/tpj.14868


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

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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