Improved plant varieties are important in our attempts to face the challenges of a growing human population and limited plant resources. Conceptually, crop improvement thus requires “reshuffling of the genome to produce new favorable gene combinations in the progeny” that occur during meiosis. Meiotic crossovers (COs) are at the heart of plant breeding and related genetic analysis such as detection of quantitative trait loci (QTLs) or gene mapping. Increasing knowledge has been gained on the underlying molecular mechanisms that govern CO formation. This has led to the identification and functional analysis of more than 80 genes involved in meiosis. Meiotic recombination initiates from DNA double-strand breaks (DSBs), which are processed into single stranded DNA that can invade a homologous chromosome. The resulting joint molecules can ultimately be resolved as crossovers or non-crossovers. Two CO pathways cohabit in most eukaryotes, including plants. The major one depends on a group of proteins collectively named ZMM and produces interfering COs. The minor pathway produces noninterfering pathway which is Mus81 dependent. Whereas non-crossovers may stem from a mechanism called SDSA (synthesis-dependent strand annealing). Despite an excess of recombination precursors, most species only form close to the one, obligatory CO per chromosome. Mechanisms underlying this limitation are currently being unraveled, but still very few anti-CO proteins are known. Three pathways that limit recombination in Arabidopsis thaliana.