Meiosis in Arabidopis thaliana: Recombination, chromosome organization and meiotic progression

Abstract

Arabidopsis has emerged as an excellent system for meiosis research due to the development of powerful cytological, genetical and molecular methodologies combined with particular biological features of plant meiosis. This chapter reviews these developments and highlights their impact on the investigation of meiotic recombination. We focus specifically on meiotic recombination, but it is important to bear in mind that research on somatic DNA repair and recombination in Arabidopsis is a highly active field. Indeed, many aspects of somatic and meiotic recombination overlap and several genes are involved in both processes. An overview of the features of meiotic recombination in Arabidopsis is obtainable from cytogenetic analysis of chiasma frequency and distribution and also from high-throughput genetic linkage analysis using molecular markers. Recombination parameters derived from these different approaches are in excellent agreement. Biotic and abiotic factors have been shown to influence recombination frequency in Arabidopsis. Forward and reverse genetic procedures have played prominent roles in the functional analysis of meiosis in Arabidopsis. A large and growing number of genes that are directly or indirectly involved in the meiotic recombination process and its regulation have been identified and analysed. These range from genes involved in the initiation of recombination through programmed double strand breaks, through the processing of these events as recombination intermediates to their final emergence as mature reciprocal crossover events (COs). Although the molecular events of recombination are largely conserved across eukaryotes, comparisons with other model species indicate some interesting though poorly understood differences. In common with other systems that have been analysed it is clear that the regulation of meiotic recombination in Arabidopsis involves a carefully programmed progressive selection of a relatively small number of recombination initiations to become COs. Evidence is also presented for the existence of more than one pathway to COs in Arabidopsis as in some other eukaryote systems. Finally, meiosis is increasingly being viewed as a highly complex series of interrelated events that are necessarily closely coordinated. In this context there is an emerging understanding, from Arabidopsis and other species, that recombination proceeds in the context of complex alterations in chromatin organization and that meiotic progression is dependent on the correct sequence and timing of these events. © 2007 Springer-Verlag Berlin Heidelberg.