AtSPO11-1 is necessary for efficient meiotic recombination in plants

The Sarcharomyces cerevisiae Spell protein catalyses DNA double-strand brea ks (DSBs) that initiate meiotic recombination. The model plant Arabidopsis thaliana possesses at least three SPO11 homologues, T-DNA and ethyl-methane sulfonate mutagenesis allowed us to show that meiotic progression is alter ed in plants in which the ACSPO11-1 gene is disrupted. Both male and female meiocytes formed very few bivalents, Furthermore, no fully synapsed chromo somes were observed during prophase I, Later, in meiosis I, we observed tha t chromosomes segregated randomly, leading to the production of a large pro portion of non-functional gametes. These meiotic aberrations were associate d with a drastic reduction in meiotic recombination. Thus, our data show th at initiation of meiotic recombination by SPO11-induced DSBs is a mechanism conserved in plants. Furthermore, unlike Drosophila and Caenorhabditis ele gans, but like fungi, SPO11 is necessary for normal synapsis in plants.