The Arabidopsis shoot apical meristem tool kit: a unifying set of cell type specific driver and effector lines for functional analysis of cellular identities in the SAM

• Applicant: Professor Dr. Wolfgang Werr
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2012 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 217062504

Genetic and molecular studies have identified numerous genes in Arabidopsis thaliana, which contribute essential components for shoot apical meristem (SAM) function, and have streamlined our conceptual view on meristem organisation, with respect to layering and zonation. With the DORNRÖSCHEN-LIKE transcription factor, we have identified a novel gene function, that marks lateral organ founder cells and expression precedes auxin maxima at the SAM periphery. This project aims to combine well-characterised, SAM-specific promoters into one set of driver lines that stably (LhG4) or inducibly (LhG4GR) address different cell types or compartments within the SAM or incipient primordia. These driver lines are characterised in combinations with different fluorophore reporters, which can concomitantly be analysed with existing stable promoter::GFP lines; immediate results will therefore be comparative promoter activities and their dynamics within the SAM. However, bona fide driver lines can then be used to predictably express transgenes in the shoot apex and be freely combined with many kinds of effector constructs. The resulting toolbox will substantially improve the repertoire of analytic methods in the shoot apex and provide a new community resource with which to access regulatory networks in the SAM. With respect to new technology developments, we will test whether cell type-specific CRE/loxP-dependent activation of the GUS reporter or inducible cell ablation with the diphtheria A toxin cell death reporter can identify clonal lineages within the SAM and elucidate on the contribution of individual cell types.

• DFG Programme: Research Grants