RESEARCH SEMINAR: Harnessing the Power of Next-Generation Genetics to Address Problems of Plant Breeding, Evolution and Speciation

Dr. Detlef Weigel
MPI for Developmental Biology, Tuebingen (Host: R. Wing)
Tuesday, March 6, 2012 - 4:00pm
Keating 103

Harnessing the Power of Next-Generation Genetics to Address Problems of Plant Breeding, Evolution and Speciation
Detlef Weigel
Max Planck Institute for Developmental Biology, Tübingen, Germany
We are investigating the three main questions of evolution: (i) How, and how frequently do new genetic variants arise? (ii) Why do some variants increase in frequency? (iii) And why are some combinations new variants incompatible with each other? To this end, we are employing bottom-up (i.e., forward genetic) and top-down (i.e., whole-genome) approaches, both of which rely heavily on second-generation sequencing. Whole-genome sequencing supports a detailed description of the pan-genome of Arabidopsis thaliana1,2 (http://1001genomes.org), it reveals mutational biases shaping the genome3, and it allows for rapid mapping of genetic variants with major phenotypic effects4. In addition, we have investigated the extent of spontaneous epigenetic variation. We discovered that it is much more heavily biased than spontaneous DNA mutation. Furthermore, reversions are frequent, indicating that unless selection is stronger than reversion, the potential of many epialleles to contribute to long-term evolution is limited5.
 
A major interest in the lab is the analysis of reproductive barriers that may ultimately lead to speciation. A few years ago, we developed A. thaliana as a model for the study of hybrid necrosis, a widespread syndrome of hybrid failure in plants, due to adverse autoimmune reactions6. Several of the causal loci are immune receptor genes, and thus members of the most polymorphic gene family in plants. While most systems involve two loci, autoimmunity can also be caused by inter-allelic interactions at a single locus that is involved in a major fitness tradeoff between growth and pathogen resistance in inbred strains7. We propose that evolutionary divergence of pathogen recognition systems can potentially result in reproductive isolation and subsequent speciation, not only by random genetic drift, but also by divergent selection due to different pathogen environments.
 
1. Schneeberger et al., Proc. Natl. Acad. Sci. USA 108, 10249 (2011). 2. Cao et al., Nat. Genet. 43, 956 (2011). 3. Ossowski et al., Science 327, 92 (2010). 4. Schneeberger et al., Nat. Methods 6, 550 (2009). 5. Becker et al., Nature, published online September 20 (2011). 6. Bomblies et al., PLoS Biol. 5, e236 (2007). 7. Todesco et al., Nature 465, 632 (2010).