• Molecular-genetic analysis of root morphogenesis:

Plant develop a fascinating diversity of different root systems which are adapted to various soil conditions and fulfill important functions as anchoring, water and nutrient acquisition and storage. Although a multitude of data on the structure of roots and their tissues were collected, the genetic basis of the development of this diversity and plasticity is largely unknown and the central aim of our research.

Figure 1: Phenotype of 10 days old cell expansion mutants of Arabidopsis thaliana

We are focusing on key parameter of morphogenesis as cell division, pattern formation, cell expansion and differentiation in the model plant Arabidopsis thaliana using classical genetic analyses and molecular-genetic, cell biological and biochemical approaches. We have isolated diverse mutants and genes which are involved in the regulation of cell division (Müller et al., 2002), pattern formation (Helariutta et al., 2000; Scheres et al., 1995) and cell expansion (Hauser et al., 1995, Aeschbacher et al., 1995). At the moment we are cloning some of these genes and initiated secondary screens to identify modulators and further components of the signaling pathways.

Arabidopsis map of mutant phenotypes

 

Although many interesting gene could be isolated with classical genetic approaches as mutant analyses, more information on structure-function relationships as well as evolutionary and adaptation processes can be deduced from the analysis of the genetic diversity of particular genes. Together with the research group of Christian Schlötterer (Institute of animal breeding and genetics, Veterinarian University Vienna) we are analyzing a group of genes which are key regulators of leaf hairs (trichomes) and root hairs (trichoblasts) development. We associate the density of trichomes in different Arabidopsis ecotypes/ accessions and closely related species to the genotype of candidate regulators (Hauser et al., 2001). Moreover we initiated a "quantitative trait loci (QTL)" analysis for loci in the determination of trichome/root hair density.

 

 

The goal in the next 10 years of international Arabidopsis functional genomics programs is to identify the molecular function of all genes . As the Arabidopsis genome codes for about 26.000 genes and about 40% of them are members of gene families, one challenge is to characterize the specific function(s) of all members of these gene families. The contribution to this aim of our lab is to characterize gene families for which our lab has at least isolated one member through mutant analyses. In cooperation with other groups we are focusing on a particular class of microtubules associated proteins, a family of putative ubiquitin E3 ligases , Mladek et al., 2003) and two putative chitinases.

 

 

 

 

In the course of the cloning of diverse genes identified by the phenotype of their mutant alleles, we developed several methods which facilitate the chromosomal walking procedure (Hauser et al., 1998; Adhami et al., 1999). Moreover for the expression analysis of genes with high sequence similarity (as members of gene families) we worked out a reliable real-time PCR  quantification method (Karsai et al., 2002).
                    Duplex Analysis Marker
                    real-time PCR