Final Report Summary - MEIOSIGHT (MEIOtic inSIGHT: Deciphering the engine of heredity)
Meiosis is an essential stage in the life cycle of sexually-reproducing organisms. Indeed, meiosis is the specialized cell division that reduces the number of chromosomes from two sets in the parent to one set in gametes, while fertilization restores the original chromosome number. Meiosis is also the stage of development when genetic recombination occurs, thus being the heart of Mendelian heredity. Increasing our knowledge on meiotic mechanisms, in addition to its intrinsic interest, have also important implications for agriculture and medicine. In the MeioSight project we used original approaches to decipher meiotic mechanisms much further, by isolating a large number of novel genes and characterizing their functions in an integrated manner. This led to major advances in our understanding of unique aspects of meiosis such as the cell cycle control that permits two divisions to follow a single replication, the mechanisms that promote a very specific mode of chromosome distribution, and the mechanisms that regulate the number and the distribution of recombination events along the genome. Of particular interest is the characterization of three pathways that act in parallel to limit meiotic recombination. Amazingly, while the number of recombination events varies in the range of one to three per chromosome in almost all eukaryotes, we showed that this frequency can be multiplied almost tenfold. This raises the question of the evolutionary factors that limit meiotic recombination in eukaryotes, and opens the perspective of exploiting further genetic diversity in plant breeding programs through the manipulation of recombination.