Rad51 tolerates mismatches in hybrid meiosis with diverse genome sequences.

Most eukaryotes possess two RecA-like recombinases (ubiquitous Rad51 and meiosis-specific Dmc1) to promote interhomolog recombination during meiosis. However, some eukaryotes have lost Dmc1. Given that mammalian and yeast () Dmc1 have been shown to stabilize recombination intermediates containing mismatches better than Rad51, we used the Pezizomycotina filamentous fungus to address if and how Rad51-only eukaryotes conduct interhomolog recombination in zygotes with high sequence heterogeneity. We applied multidisciplinary approaches (next- and third-generation sequencing technology, genetics, cytology, bioinformatics, biochemistry, and single-molecule biophysics) to show that Rad51 (Rad51) is indispensable for interhomolog recombination during meiosis and, like Dmc1, Rad51 possesses better mismatch tolerance than Rad51 during homologous recombination. Our results also indicate that the ancestral Rad51 evolved to acquire Dmc1-like properties by creating multiple structural variations, including via amino acid residues in the L1 and L2 DNA-binding loops.