Growth and Development of higher plants

During the previous network P1A developed a research strategy to unravel the molecular mechanisms controlling the branching of roots. This resulted in a unique dataset reflecting the transcriptional changes associated with the initiation of lateral roots. An additional transcriptome analysis based on cell sorting refined the still extensive list of candidate “lateral root initiation” genes to a set of potential regulatory genes involved in asymmetric cell division, a hallmark of the onset of many vital developmental processes in both plants and animals.
In the present work package, P1A will continue on the same path and concentrate on the functional analysis of potential regulators of lateral root initiation and/or asymmetric cell division. Classically, functional analysis of regulatory genes relies almost entirely on the study of knock-out mutants. However, inherent to vital regulatory genes, such mutations will most likely be lethal. In the coming phase of the network we want to exploit the benefits of a chemical genetics approach to intercept key regulators of the process of lateral root initiation (see Integrated Advanced Techniques).
Chemical genomics makes use of small molecules to disturb signal transduction cascades allowing the identification of the involved proteins. The project aims at the identification of inhibitory or activating compounds of cell cycle activation in the root. A chemical library of 10 000 compounds will be tested on the potential effect of certain chemicals during the very early phases of lateral root formation using a well established lateral inducible system.
Once candidate compounds, negatively or positively influencing the process of asymmetric cell division, will be identified and validated, the bioactive aspects can be worked out further in collaboration with the other partners of the network.
In a first instance, the changes in the proteome upon application of the bioactive compound will be analysed. Such analysis will contribute seriously towards the elucidation of the target-pathway of the compound.
Within this project the isolated compounds can easily be tested for their role in or interference with other root developmental processes such as endoreduplication (P1B), hormonal signalling cascades (P1D), primary root growth rate (P1C), cell elongation (P5) and root/shoot crosstalk during floral induction (P2).
Furthermore, the experimental set-up and the library of the chemical genomics platform can made available for the partners of the network to perform their own screenings using the appropriate conditions and markers related to their projects.
Finally, in the recent post-genomic era the accumulation of an enormous amount of data necessitates the implementation of modelling. Therefore, we want to model the early cell division patterns of lateral root initiation in spatially-structured models combined with a modelling of the molecular networks involved (see WP6, in collaboration with P1C, P4C, EU1).