Calendar Name:	seminars
Scheduled for:	Friday, May 28 2010, 14:00 - 15:30
Event text:	Dr Rapha?l Mercier G?n?tique et Am?lioration des Plantes INRA - Centre de Versailles Grignon FRANCE
Details:	"Turning meiosis into mitosis and other games with meiosis" ABSTRACT Apomixis, or asexual clonal reproduction through seeds, is of immense interest due to its potential revolutionary application in agriculture. One key element of apomixis is apomeiosis, a deregulation of meiosis which results in a mitotic-like division. Meiosis halves the chromosome number because its two divisions follow a single round of DNA replication. This process involves two cell transitions, the prophase to meiosis I transition and the unique meiosis I to meiosis II transition. We show that OSD1 and the A-type cyclin CYCA1;2/TAM play a major role in both transitions in Arabidopsis. A series of osd and tam mutants failed to enter meiosis II and thus produced diploid spores and functional diploid gametes. These diploid spores had a recombined genotype produced through the single meiosis I division. Combining tam and osd1 mutations lead to a failure in the prophase to meiosis I transition during male meiosis and to the production of tetraploid spores and gametes. This suggests that TAM and OSD1 are involved in the control of both meiotic transitions. In addition, by combining either the osd or the tam mutation with two others affecting key meiotic processes (spo11-1 and rec8), we obtained plants producing diploid gametes through a mitotic-like division, that were genetically identical to their parents. The obtained plants, called MiMe-1 and MiMe-2 respectively, produce functional diploid gametes that are genetically identical to their mother. Creation of the MiMe genotypes and apomeiosis phenotype is an important step towards understanding and engineering apomixis.