Auxin Signaling

With >1000 publicly available natural accession of Arabidopsis thaliana, many of them completely sequenced, naturally occurring genetic variation in this gene pool represents a powerful resource to analyze the genetic architecture of important traits.

We are primarily interested to tap this natural resource to better understand plant development and adaptation, primarily those phenotypes that are controlled by the phytohormone auxin. We find a tremendous degree of variation for such auxin-dependent phenotypes in screens of several hundred natural accessions (Delker et al., 2008). To unravel the underlying genetics, we are primarily following quantitative genetic (QTL, GWAS) and transcriptional (expression level polymorphisms) approaches (Delker et al., 2010; Delker and Quint, 2011). In a complementary

approach, we are investigating selection signatures of the genes that regulate auxin biology by means of molecular population genetics.

Temperature is one of the most fundamental abiotic factors that profoundly affect plant physiology and development. While responses to temperature extremes (freezing/heat) have been intensively studied over the past decades, responses to moderate temperature differences have received little attention. Plants can sense and respond to even little changes in their ambient temperature with morphological and developmental adjustments. Yet, the molecular components and hierarchies of the underlying regulatory network are poorly understood. To unravel the molecular mechanisms that facilitate these responses we exploit natural variation in the wordlwide Arabidopsis thaliana germplasm using quantitative, forward genetic and transcriptomic approaches.

Several approaches can be applied to address the evolution of plant development. An important tool in this regard is based on phylogenetics. We are using phylogenetics for two different purposes:

(i) we reconstruct the evolutionary histories of gene families that shape plant development (Schumann et al., 2011, Janitza et al., 2011), and

(ii) we combine phylogenetics with whole genome transcriptome information to investigate developmental processes in land plants (Quint et al., 2012). The latter approach can be defined as phylotranscriptomics, which we are currently using to learn more about the classic developmental hourglass concept.