Heterologous Complementation of SPO11-1 and -2 Depends on the Splicing Pattern.

In the past, major findings in meiosis have been achieved, but questions towards the global understanding of meiosis remain concealed. In plants, one of these questions covers the need for two diverse meiotic active SPO11 proteins. In Arabidopsis and other plants, both meiotic SPO11 are indispensable in a functional form for double strand break induction during meiotic prophase I. This stands in contrast to mammals and fungi, where a single SPO11 is present and sufficient. We aimed to investigate the specific function and evolution of both meiotic SPO11 paralogs in land plants. By performing immunostaining of both SPO11-1 and -2, an investigation of the spatiotemporal localization of each SPO11 during meiosis was achieved. We further exchanged SPO11-1 and -2 in Arabidopsis and could show a species-specific function of the respective SPO11. By additional changes of regions between SPO11-1 and -2, a sequence-specific function for both the SPO11 proteins was revealed. Furthermore, the previous findings about the aberrant splicing of each SPO11 were refined by narrowing them down to a specific developmental phase. These findings let us suggest that the function of both SPO11 paralogs is highly sequence specific and that the orthologs are species specific.