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Biennial department retreat Bad Urach

Posted on May 28, 2017

We spent May 18-19 in Bad Urach read more

A great two days in Bad Urach, discussing not only exciting science, but also how we can improve ourselves as scientists, both individually and as a team.

With Mathieu lab: TE-related plant proteins in gene silencing

Posted on May 12, 2017

Latest paper: Arabidopsis proteins with a transposon-related domain act in gene silencing read more

Arabidopsis proteins with a transposon-related domain act in gene silencing

Yoko Ikeda, Thierry Pélissier, Pierre Bourguet, Claude Becker, Marie-Noëlle Pouch-Pélissier, Romain Pogorelcnik, Magdalena Weingartner, Detlef Weigel, Jean-Marc Deragon & Olivier Mathieu

Nature Communications 8, Article number: 15122 (2017) doi:10.1038/ncomms15122

Transposable elements (TEs) are prevalent in most eukaryotes, and host genomes have devised silencing strategies to rein in TE activity. One of these, transcriptional silencing, is generally associated with DNA methylation and short interfering RNAs. Here we show that the Arabidopsis genes MAIL1 and MAIN define an alternative silencing pathway independent of DNA methylation and short interfering RNAs. Mutants for MAIL1 or MAIN exhibit release of silencing and appear to show impaired condensation of pericentromeric heterochromatin. Phylogenetic analysis suggests not only that MAIL1 and MAIN encode a retrotransposon-related plant mobile domain, but also that host plant mobile domains were captured by DNA transposons during plant evolution. Our results reveal a role for Arabidopsis proteins with a transposon-related domain in gene silencing.

RNA helicases and hybrid breakdown in A. thaliana

Posted on May 09, 2017

Chlorosis caused by two recessively interacting genes reveals a role of RNA helicase in hybrid breakdown in Arabidopsis thaliana read more

Chlorosis caused by two recessively interacting genes reveals a role of RNA helicase in hybrid breakdown in Arabidopsis thaliana

Björn Plötner, Markus Nurmi, Axel Fischer, Mutsumi Watanabe, Korbinian Schneeberger, Svante Holm, Neha Vaid, Mark Aurel Schöttler, Dirk Walther, Rainer Hoefgen, Detlef Weigel, Roosa A. E. Laitinen

Plant J. 2017 Apr 4. doi: 10.1111/tpj.13560

Hybrids often differ in fitness from their parents. They may be superior, translating into hybrid vigour or heterosis, but they may also be markedly inferior, because of hybrid weakness or incompatibility. The underlying genetic causes for the latter can often be traced back to genes that evolve rapidly because of sexual or host-pathogen conflicts. Hybrid weakness may manifest itself only in later generations, in a phenomenon called hybrid breakdown. We have characterized a case of hybrid breakdown among two Arabidopsis thaliana accessions, Shahdara (Sha, Tajikistan) and Lövvik-5 (Lov-5, Northern Sweden). In addition to chlorosis, a fraction of the F2 plants have defects in leaf and embryo development and reduced photosynthetic efficiency. Hybrid chlorosis is due to two major-effect loci, of which one, originating from Lov-5, appears to encode an RNA helicase (AtRH18). To examine the role of the chlorosis allele in the Lövvik area, in addition to eight accessions collected in year 2009, we collected another 240 accessions from 15 collections sites, including Lövvik, from Northern Sweden in year 2015. Genotyping revealed that Lövvik collection site is separated from the rest. Crosses between 109 accessions from this area and Sha revealed 85 cases of hybrid chlorosis, indicating that the chlorosis causing allele is common in this area. These results suggest that hybrid breakdown alleles not only occur at rapidly evolving loci, but also at genes that code for conserved processes.

 

Sediment DNA revolutionizing ancient genetics

Posted on April 28, 2017

Targeted enrichment of sediment DNA revolutionizing ancient genetics read more

Neandertal and Denisovan DNA from Pleistocene sediments

Viviane Slon, Charlotte HopfeClemens L. Weiß, Hernán A. Burbano, Svante Pääbo, Matthias Meyer

Although a rich record of Pleistocene human-associated archaeological assemblages exists, the scarcity of hominin fossils often impedes the understanding of which hominins occupied a site. Using targeted enrichment of mitochondrial DNA we show that cave sediments represent a rich source of ancient mammalian DNA that often includes traces of hominin DNA, even at sites and in layers where no hominin remains have been discovered. By automation-assisted screening of numerous sediment samples we detect Neandertal DNA in eight archaeological layers from four caves in Eurasia. In Denisova Cave we retrieved Denisovan DNA in a Middle Pleistocene layer near the bottom of the stratigraphy. Our work opens the possibility to detect the presence of hominin groups at sites and in areas where no skeletal remains are found.

 

March for Science Tübingen

Posted on April 22, 2017

Great turnout -- 2700 marched in Tübingen read more

Article (in German) in our local newspaper

Dangerous Mix NLR proteins in autoimmunity: higher order complexes

Posted on April 14, 2017

Activation of a Plant NLR Complex through Heteromeric Association with an Autoimmune Risk Variant of Another NLR read more

Tran, D.T.N., Chung, E.H., Habring-Müller, A., Demar, M., Schwab, R., Dangl, J.L., Weigel, D., Chae, E.

When independently evolved immune receptor variants meet in hybrid plants, they can activate immune signaling in the absence of non-self recognition. Such autoimmune risk alleles have recurrently evolved at the DANGEROUS MIX2 (DM2) nucleotide-binding domain and leucine-rich repeat (NLR)-encoding locus in A. thaliana. One of these activates signaling in the presence of a particular variant encoded at another NLR locus, DM1. We show that the risk variants of DM1 and DM2d NLRs signal through the same pathway that is activated when plant NLRs recognize non-self elicitors. This requires the P loops of each protein and Toll/interleukin-1 receptor (TIR)-domain-mediated heteromeric association of DM1 and DM2d. DM1 and DM2d each resides in a multimeric complex in the absence of signaling, with the DM1 complex shifting to higher molecular weight when heteromerizing DM2 variants are present. The activation of the DM1 complex appears to be sensitive to the conformation of the heteromerizing DM2 variant. Autoimmunity triggered by interaction of this NLR pair thus suggests that activity of heteromeric NLR signaling complexes depends on the sum of activation potentials of partner NLRs.

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Upcoming Events

Jul
03

SMBE 2017


Jul
18

GRC Ecological & Evolutionary Genomics

July 16-21, 2017
Biddeford, ME, USA

Hernán Burbano speaking about "Genomic Estimation of Complex Traits Reveals Ancient Maize Adaptation to Temperate North America"


Sep
12

IMPRS PhD Student Symposium

September 11-14
in Göttingen, Germany

Detlef speaking at International Horizons in Molecular Biology Symposium: "Genetics and epigenetics of adaptation to the environment"