Research objectives and content
In the host laboratory a series of Arabidopsis mutants have been isolated which have profound defects in early development. The ton mutants are dwarf and have surernumary cell layers. Cells have an aberrant shape and are unable to elongate, whatever stimuli applied. However, the general organisation is conserved, all organs and cell types being present. These mutants are altered in cytoskeleton, and the preprophase band is never observed, which apparently leads to a complete disorganization of division planes.
Why are these mutants, which are strongly altered in cell division and cell elongation, still capable of partial organogenesis? In order to answer this question, the cloning of the ton1 and ton2 loci has been undertaken. The ton2 gene is currently being cloned by a positional cloning approach. The ton I locus have been isolated from a T-DNA tagged allele. The mutation affects two genes in tandem, very similar to one another. These genes encode small acidic proteins, which do not show striking similarity to proteins of known function.
The work proposed here aims at elucidating the biochemical function of the ton1 proteins. The strategy involves the localization of the protein by immune-cytology using confocal microscopy; promoter fusions to the green fluorescent protein to localise transcription. Partner proteins will be isolated by the two-hybrid yeast cloning system. The final steps of positional cloning of the gene will also be undertaken by the applicant. Training content (objective, benefit and expected impact)
In the Versailles laboratory of the l.N.R.A the applicant will have the opportunity to learn most of the up to date gene analysis techniques and concepts in the field of plant developmental biology and to acquire experience on the specific genetic tools available in the widely used model species Arabidopsis thaliana. This knowledge as much as the contact with the host laboratory will expand the scientific knowledge and prospects of the applicant in future research projects.
Links with industry / industrial relevance (22)
Genes as ton genes are key players in establishing plant architecture. The study of these genes is fontamental for the further manipulation of agronomical traits in cultivated plants.