Haploidisation

Abstract: In yeast, the DMC1 gene is required for interhomolog recombination, which is an essential step for bivalent formation and the correct partition of chromosomes during meiosis I. By using a reverse genetics approach, we were able to identify a T-DNA insertion in AtDMC1, the Arabidopsis homolog of DMC1. Homozygotes for the AtDMC1 insertion failed to express AtDMC1, and their residual fertility was 1.5% that of the wild type. Complete fertility was restored in mutant plants when a wild-type copy of the AtDMC1 gene was reintroduced. Cytogenetical analysis points to a correlation of the sterility phenotype with severely disturbed chromosome behavior during both male and female meiosis. In this study, our data demonstrate that AtDMC1 function is crucial for meiosis in Arabidopsis. However, meiosis can be completed in the Arabidopsis dmc1 mutant, which is not the case for mouse or some yeast mutants.

Abstract: INTRODUCTION Sporulation in yeast includes meiosis and ascospore development. It has been the focus of numerous studies for two primary reasons. First, it provides a relatively simple model system for the investigation of eukaryotic differentiation and the manner in which a complex series of biochemical, morphological, and genetic events are coordinated into a successful developmental pathway. Second, two events of major genetic consequence occur during meiosis: genetic recombination and chromosome segregation. Both of these events play a profound role in the generation of new genotypes and euploid genomes during sexual reproduction. Despite the central importance of the meiotic process, specific knowledge of the genetic and biochemical control of gametogenesis in eukaryotic organisms is very limited. Utility of Yeast For Studies of Sporulation As an experimental system, yeast presents the opportunity to study meiosis and gamete development in an organism that possesses all of the technical advantages of microbial systems, while exhibiting chromosome behavior typical of higher eukaryotic cells. It has a number of attractive features that make it particularly well-suited for an analysis of meiotic cell differentiation: (1) Yeast has well-developed genetics and is readily manipulated biochemically. (2) Large numbers of single cells can be stimulated to undergo meiosis in a defined medium. (3) Meiosis can be interrupted and viable cells recovered at various stages of development. (4) All of the meiotic products of a given meiosis can be recovered in association with one another, permitting precise reconstruction of exchange and segregation events. (5) Aspects of the life cycle and...