Research objectives and content
In angiosperms, first pollen mitosis is a key event in the differentiation of the male gametophyte which determines the correct development of the sperm cells necessary for double fertilization, and therefore for plant fertility. Futhermore, this asymmetric division provides a rare opportunity to study the cellular and molecular basis for the establishment of cell polarity in plants. The laboratory directed by Dr. David Twell (Botany Department, University of Leicester, UK), has isolated a large number of Arabidopsis gametophytic mutants affected in cell division at first pollen mitosis. Six of these mutants show an alteration of the symmetry of microspore division: the microspore divides more symmetrically instead of asymmetrically. This symmetric division is followed by an incomplete or absent generative cell differentiation, indicating that this differentiation is critically dependent upon asymmetric cell division. The principal aims of the proposed work are to establish in detail the developmental profile of two of these Arabidopsis gametophytic mutants using cytological (confocal and electron microscopy) and genetic (crosses with mutant and transgenic lines) approaches (duration: 12 months), and to clone by transposon tagging the gene(s) responsible for these specific mutant phenotypes (duration: 24 months).
Training content (objective, benefit and expected impact)
The results may be of direct benefit in understanding fundamental developmental events in plants and animals which involve the establishment of cell polarity.