Dr. Kirsten Bomblies

I am interested in many different topics in evolutionary genetics, especially those pertaining to speciation and population dynamics. My newest interests lie in how landscape affects populations, and how plant species adapt to their biological and physical environments.

Hybrid necrosis:

Recently I have been focusing in most detail on the effects of hybridization in Arabidopsis thaliana, which is primarily - but not exclusively - selfing in the wild. Our reasoning is that since A. thaliana is primarily selfing, generally seen as a difficulty in evolutionary genetics, it in fact provides a very nice system for studying the earliest effects of genetic divergence, whether through adaptive or neutral processes. In a large intercrossing survey, we found that crosses between some strains generate progeny with severely deleterious phenotypes (mostly hybrid necrosis - where the plant's own cells die off in large numbers). In these cases we have identified over-activation of the plant immune system as causal, suggesting that this is a form of plant autoimmunity. Indeed, in one case we have identified a member of a gene class implicated in pathogen resistance as causal for necrosis in the genetic context of the other parent. In a second case, we have found another type of resistance gene to be involved. These genes are fully functional and "normal" - perhaps even beneficial - in their native genetic context, but lead to hyperactivation of the plant immune system in specific genetic contexts to which they are not adapted. This may place context-dependent constraints on the "genotype space" that resistance genes can explore during their evolution.

We have hypothesized that a similar physiological mechanism may underlie a large number of published necrosis cases in other species, including many crop and wild species, and that this phenomenon could contribute to post-zygotic gene flow barriers in plants. An important implication for crop breeding is that breeding for increased resistance to pathogens may sometimes lead to undesired side effects that will be inextricable from the resistance phenotype. To what degree hybrid necrosis mechanisms may affect resistance gene evolution, host-pathogen co-evolutionary dynamics, or plant differentiation is an area of research I will explore in more detail in the future.

In addition to necrosis, we identified several crosses in which F1 and F2 progeny had different phenotypes, including chlorosis and several types of inflorescence morphology defects. We are currently also mapping these and trying to understand what molecular mechanisms underlie these.

Our publications related to this topic:

2007    Bomblies, K.*, Lempe, J.*, Epple, P., Warthmann, N., Lanz, C., Dangl, J. L. and Weigel, D. Autoimmune response as a mechanism for a Dobzhansky-Muller type incompatibility syndrome in plants. PLoS Biol. 5, pp. 1962-1972.

*Indicates equal contribution by these authors

2007    Bomblies, K., and Weigel, D. Hybrid necrosis: Autoimmunity as a potential gene flow barrier for plant species. Nature Reviews Genetics 8, pp. 382-389.
 

2007    Bomblies, K. and Weigel, D. Arabidopsis- a model genus for speciation. Current Opinion in Genetics and Development. 17, pp. 500-504.

2006    Bomblies, K. Hybrid incompatibility: When opposites attract with a fatal outcome. Dispatch article. Current Biology 16, pp. R542-544.

I generated a large collection of local accessions from around Tübingen in 2007, together with my husband Levi Yant. 1300 plants have been genotyped at 450 SNP loci scattered throughout the genome (1100 plants from 95 sites around Tübingen, 100 plants from the Costa Brava in Spain, and 100 from elsewhere). I am currently analyzing these data together with Roosa Laitinen. We are analyzing local population structure and outcrossing rates. Thus far we have found a surprising amount of diversity - among the 1000 individuals genotyped thus far from Tübingen, we have found 220 unique genotypes and a number of heterozygotes where in some cases the parent genotypes are readily identifiable within the same population. We are currently investigating how much the observed hybridization affects genetic and phenotypic diversity in the wild.

We are currently writing up a publication on this topic.

Natural variation in A. thaliana:

Together with Patrice Salomé, Roosa Laitinen and Levi Yant, I participated in generating 17 populations for QTL analysis. We are performing growth analysis and analyzing several architectural traits as well to compare QTL across different genetic contexts.

Arabidopsis arenosa landscape/population genetics (and adaptation?)

I am making a collection of Arabidopsis arenosa subspecies borbasii in order to study local population structure and environmental adaptation. This subspecies grows only on limestone outcrops, and is only incidental in surrounding forests, while subspecies arenosa is much more broadly distributed. I have found A. a. borbasii at many sites throughout the Swabian Alb, a Jurassic limestone highland near Tübingen with numerous limestone outcrops. I would like to investigate whether the observed distribution patterns reflect specific adaptation and whether the exclusive growth on isolated limestone outcrops and associated rockfalls affects gene flow or promotes divergence (i.e. are there geographic barriers to gene flow and is there outbreeding depression?). I would also like to investigate how the landscape affects fine-scale population structure, and how much stretches of unsuitable habitat affect gene flow in this subspecies.

Arabidopsis arenosa is an outcrossing species, and thus it will also be interesting to compare its local population genetics to our A. thaliana collection from this area, since the distributions of both species are similarly patchy and both inhabit marginal habitats, while most other aspects of their respective lifestyles are very different.

*Please note*

I will be starting my own group at the Organismic and Evolutionary Biology Department at Harvard University in July, 2009 and will be looking for postdocs and graduate students to continue working on some of these, or new topics. If interested, please contact me.

*BIG NEWS!*

I am extremely honored to announce that I have received a 2008 MacArthur fellowship. I plan to use this to boost my research endeavors as well as my art, and hope to some day write or edit a scientific book (we'll see!). I am extremely excited, and was taken completely by surprise! It is a testimony to my wonderful mentors over the years and also to the wonderful intellectual freedom one enjoys at the MPI.

My history:

Other (older) papers:

2006    Bomblies, K. and Doebley, J. Pleiotropic effects of the duplicate maize FLORICAULA/LEAFY genes zfl1 and zfl2 on traits under selection during maize domestication. Genetics 172, pp. 519-531.
   
2005    Wang, H., Nussbaum-Wagler, T., Li, B., Zhao, Q., Vigouroux, Y., Faller, M., Bomblies, K., Lukens, L. and Doebley, J. The origin of the naked grains of maize. Nature 436, pp. 714-719.

2005    Bomblies, K. and Doebley, J. Molecular evolution of FLORICAULA/LEAFY orthologs in Zea mays and related grasses within tribe Andropogoneae. Molecular Biology and Evolution 22, pp. 1082-1094.

2005    Yoo, S. Y., Bomblies, K., Yoo, S. K., Yang, J. W., Choi, M. S., Lee, J. S., Weigel, D. and Ahn, J. H. The 35S promoter used in a selectable marker gene of a plant transformation vector affects the expression of the transgene. Planta 221, pp. 523-530.

2003    Bomblies, K., Wang, R.L., Ambrose, B.A., Schmidt, R.J., Meeley, R.B., and Doebley, J. Duplicate FLORICAULA/LEAFY homologs zfl1 and zfl2 control inflorescence architecture and flower patterning in maize. Development 130, pp. 2385-2395.

2002    Parcy, F.*, Bomblies, K.*, and Weigel, D. Interaction of LEAFY, AGAMOUS, and TERMINAL FLOWER1 in maintaining floral meristem identity in Arabidopsis. Development 129, pp. 2519-2527.
    *Indicates equal contribution by these authors

2001    Kerstetter, R.A., Bollman, K., Taylor, R.A., Bomblies K., and Poethig, R. KANADI regulates organ polarity in Arabidopsis. Nature 411, pp. 706-709.

2001    Bomblies, K., Shukla, V., and Graham, C. Standard SEM protocol.
Bomblies, K., Whole Mount GUS staining. Both in: Weigel, D. and Glazebrook, J. Arabidopsis- A Laboratory Manual. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. pp.106-108 and 243-248.

1999    Bomblies K., Dagenais N, and Weigel, D. Redundant Enhancers Mediate Transcriptional Repression of AGAMOUS by APETALA2. Developmental Biology 216, pp. 260-264.

1999    Busch, M.*, Bomblies, K.*, and Weigel, D. Activation of a Floral Homeotic Gene in Arabidopsis. Science 285, pp. 585-587.
    *Indicates equal contribution by these authors