A genetic approach for the identification of factors regulating cell polarity in Arabidopsis thaliana
09 / 2006 - 08 / 2009
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
In the 1970?s a model for polar auxin transport has been proposed. The most important aspect of this model is that the auxin efflux carrier has to be localised predominantly towards one side of the cell, thereby assuring that auxin transport is occurring in one direction. The family of PIN proteins has been proposed to be involved in auxin transport and they are asymmetrically localised within the cell, suggesting that these proteins represent components of the auxin efflux machinery. As yet unknown cell polarity determinants, which depend on processes like vesicle trafficking, GTPase activity, kinase activity and sterol composition, determine the accurate localisation of PIN proteins, which in turn affects polar auxin transport. A pivotal question is how cell polarity and thereby PIN localisation is regulated and/or modulated. The working hypothesis can be put forward that PIN proteins are markers of cell polarity. When PIN proteins are regarded as markers for cell polarity they allow for the identification of cell polarity cues. The sub-cellular localisation and/or targeting of PIN proteins are important for their function in the efflux machinery. In a mutant screen, designed to identify mutants that are affected in polar PIN localisation, I will make use of novel complementing PIN2:GFP fusions in two different mutant backgrounds, which will allow targeted selection of mutants. The experimental approach, proposed in this application, can be expected to result in the identification of a new regulatory framework, affecting Arabidopsis development via the control of cell polarity and auxin transport.