Exploitation of genes affecting meiotic non-reduction and nuclear restitution: Arabidopsis as a model?

Meiosis is a fascinating and complex phenomenon with intriguing practical potential. Some deviations in meiotic reduction are crucial for plant evolution and extremely important for plant breeding. In particular, the production of gametes with unreduced chromosome number and the diplosporic pathway of apomixis hold great promise for the genetic improvement of cultivated plants. The use of meiotic mutations is hampered by the fact that they do not occur widely in crop plants, and traditional breeding approaches to transfer these characters are difficult or impossible. For their exploitation, genetic engineering has been suggested as a promising and more direct way. Since molecular advances for isolating meiotic genes in flowering plants have been pursued mostly in Arabidopsis thaliana, mutants of this plant with alterations in meiotic reduction or meiotic nuclear restitution are the main focus of this review. Emphasis has been given to the cytological description of mutated phenotypes, their effect on male/female fertility, and to gene function. Perspectives for using meiotic genes of Arabidopsis to manipulate whole genomes through 2n gametes and for the exploitation of apomixis are also discussed.