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Prof. Dr. Wolfgang Werr

Embryonic patterning

    Starting from the single-celled zygote, a stereotypic pattern of cell divisions in Arabidopsis thaliana establishes the plant body axes and the anlagen of the shoot apical meristem (SAM) or the basal root meristem (RM). Genetic analyses have identified multiple gene functions and identified auxin synthesis, transport and perception as a major player during embryonic pattering. The genes DORNRÖSCHEN(DRN) and DRN-like (DRNL) encode AP2/ERF-type transcription factors and act redundantly upstream of auxin signalling and in the establishment of apical and basal positional information. Genetic, molecular and cell biological approaches are being pursued to identify and unravel regulatory networks specifying cellular decisions in the early globular Arabidopsis embryo.


Figure 1:
Cotyledon phenotypes of drn mutants include mono- cotyledony, fused cotyledons, tricotyledony or in the most extreme cases, complete cup-shaped cotyledons.

Shoot apical meristem function

    Research in Arabidopsis thaliana has shown that a central stem cell population is essential for maintainance and function of shoot apical meristem. Cells released at the stem cell zone periphery acquire positional cues within the SAM before they are recruited for lateral organ primordia and ultimately differentiate to form the plant body. Pronounced differences in plant architecture make it tempting to compare the orthologous gene functions between distant species to unravel fundamental similarities or differences in SAM function. Major foci are comparative approaches between Arabidopsis and maize, centred on genes which contribute to SAM function in the Arabidopsis model.

Evolutionary developmental biology

    Members of the WUSCHEL related homeobox (WOX) gene family promote stem cell fate in the SAM or RM and are sophisticated molecular markers during embryo development. DNA sequence conservation of the homeodomain (HD) enables bioinformatic or PCR based approaches to identify WOX family members across species. From mosses (Physcomitrella patens) or basal vasular plants (Selaginella moellendorffii) through gymnosperms to angiosperms. the phylogenetic reconstructions reveal increasing gene numbers with a complete set in basal angiosperms such as Amborella trichopoda, Nymphaea jamesoniana. Comparative expression and functional studies are currently being performed.